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Carbon Nanotubes and Oxide Nanowires Synthesis Properties and Applications
Carbon Nanotubes and Oxide Nanowires Synthesis Properties and Applications
Koungmin RyuAdvisor Prof Chongwu Zhou
Ming Hsieh Dept of Electrical EngineeringViterbi School of Engineering
University of Southern Californiahttpnanolabuscedu
Funded by SRC NSF Intel NASA DARPA NIH Whittier
My Research
Nanoelectronicsbull Nanoscale transistors bull Nanoscale memoriesbull Circuits
Nanobiotechnologybull Biosensingbull Nano therapybull Drug delivery
Nano Materials
bull Carbon nanotubesbull NanowiresbullGraphene
oxLDLantibodyElectrode
PEIPEGNanowireNanotube
Si Substrate
SiO2
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Original MotivationMoorersquos Law
Original MotivationMoorersquos Law
1950 1970 1990 2010 2030
1 m
1 cm
Year
VLSI
Integratedcircuits
Transistor
Vacuum valves
Molecular dimensions
1 μm
10 nm
1 Α
Device size
From Intel
Si Substrate
Metal Gate
High-kTri-Gate
S
G
D
III-V
S
Carbon Nanotube FET
50 nm35 nm
30 nm
SiGe SD
Strained Silicon
Future options subject to research amp change
SiGe SD
Strained Silicon
90 nm65 nm
45 nm32 nm
20032005
20072009
2011+
Technology Generation
Source Intel
20 nm 10 nm
5 nm5 nm
5 nm
Nanowire
Manufacturing Development Research
Transistor Research
Research OptionsHigh-K amp Metal GateNon-planar TrigateIII-V CNT NW
CNT is a tubular form of carbon with diameter as small as 1 nm Length few nm to cm
CNT is configurationally equivalent to a two dimensional graphenesheet rolled into a tube
CNT exhibits1 Carrier mobility ~ 100000 cm2Vs2 Youngrsquos modulus over 1 Tera
Pascal as stiff as diamond3 Tensile strength ~ 200 GPa
Zigzag
Armchair
Chiral
MOLECULAR STRUCTUREMOLECULAR STRUCTURE
CNT can be metallic or semiconducting depending on chirality
Benchmarking CNT FETsBenchmarking CNT FETs
1
10
100
1000
10000
100000
130 90 65 45 22
Technology Node (nm)
Nor
mal
ized
FO
A
26X25X
28X 27X
Intrinsic CNT
MOS CNT FET
Band-edge SB CNTMidgap SB CNT
5000X
60X
50X20X
Si MOSFET
Source Ali Keshavarzi Intel
Nanotube Transistor ResearchNanotube Transistor ResearchGate
8nm HfO2
SiO2
p++ Si
PdPd CNT
Javey et al Nano Letters 4 1319 2004Delft Tans et al Nature 393 49 1998
Many people have studied individual nanotube transistors however the challenge is to integrate nanotube devices
Many people have studied individual nanotube transistors however the challenge is to integrate nanotube devices
Appenzeller et al PRL 93 19 2005
Drain
SourceGate
DrainSourceGate
Sapphire Substrate
GateOxide
Liu et al Nano Letters 6 34 2006
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Traditional approach On-Site Synthesis of Single-Walled Carbon Nanotubes
Traditional approach On-Site Synthesis of Single-Walled Carbon Nanotubes
SiSiO2
PMMA
Catalyst
CH4nanotube
Catalyst island
900 ordmC900 ordmC
metal electrode
H Dai et al Nature 395 878 (1998)
Infrastructure Nanotube CVD Generation IInfrastructure Nanotube CVD Generation I
1 μm
1 μm
26 nm in diameter
10 nm in diameter
High-quality nanotubes can be grown at specific positions
-60
-50
-40
-30
-20
-10
0
I DS(
nA)
-10-08-06-04-0200VDS(V)
Vg -4 V
0 V
2 V
6 V
Nanotube transistor can be easily produced
Si back gate
SiO2
S D
Integrated Nanotube SystemsComplementary Carbon Nanotube Inverter
Integrated Nanotube SystemsComplementary Carbon Nanotube Inverter
Carbon Nanotube Field-Effect Inverters X Liu R Lee J Han C Zhou Appl Phys Lett 79 3329 (2001)
One of the first integrated systems made of carbon nanotubes
Si back gate
K
Vin
Vout
VDD GND
p-type CNT n-type CNT
60
40
20
0
I DS(
nA)
-4 -2 0 2 4Vg(V)
VDS=10 mV
P type MOSFET12
8
4
0
I DS (
nA)
-4 -2 0 2 4Vg (V)
VDS=10 mV
N type MOSFET25
20
15
10
05
00
Vou
t(V)
252015100500Vin(V)
VDD=29 V
Vin Vout
0 V
VDD
p
n
Integrated Nanotube SystemsRing Oscillators Demonstrated by Avouris et al
Integrated Nanotube SystemsRing Oscillators Demonstrated by Avouris et al
Ph Avouris et al Science 311 1735 (2006)
Is there a way to assemble large quantities of nanotube devices
State-of-the-art of nanotube integration
Aligned Nanotubes for Devices and Circuits Aligned Nanotubes for Devices and Circuits
-- Project Mission Project Mission We want to tackle the challenging issue of We want to tackle the challenging issue of nanotube nanotube assembly and integrationassembly and integration
We want to grow carbon nanotubes withWe want to grow carbon nanotubes withControlled orientation (achieved by using Controlled orientation (achieved by using sapphire and quartz) sapphire and quartz) Controlled position (achieved) Controlled position (achieved) Controlled density (achieved) Controlled density (achieved) Controlled diameter (ongoing)Controlled diameter (ongoing)Controlled Controlled chiralitychirality (ongoing)(ongoing)
-- Our Approach Our Approach A novel nanotubeA novel nanotube--onon--insulator (NOI) insulator (NOI) approach based on approach based on aligned nanotubesaligned nanotubes for for integrated nanotube circuitsintegrated nanotube circuits Nanotube
devicesNanotube
circuits
Quartz SubstrateCatalyst Particle
Quartz Substrate
Nanotube
One of the first to grow aligned nanotubes on sapphireOne of the first to grow aligned nanotubes on sapphireJ of Am Chem Soc 127 5294 J of Am Chem Soc 127 5294 -- 5295 (2005) 5295 (2005)
The first to make aligned nanotube transistorsThe first to make aligned nanotube transistorsNano Letters 6 34Nano Letters 6 34--39 (2006)39 (2006)Reported by Reported by Scientific AmericanScientific American (April 2006 P16) (April 2006 P16)
The first to demonstrate waferThe first to demonstrate wafer--scale processing of aligned scale processing of aligned nanotube devices and circuitsnanotube devices and circuits
Logic circuits (CMOS inverter NAND NOR)Logic circuits (CMOS inverter NAND NOR)
The first to make transparent nanotube devicesThe first to make transparent nanotube devicesACS Nano in press (2008)ACS Nano in press (2008)
Chip
1
2
3
4
5
Our Achievements on Aligned Single-Walled NanotubesOur Achievements on Aligned SingleOur Achievements on Aligned Single--Walled NanotubesWalled Nanotubes
Synthesis of Aligned Nanotubes on Sapphire QuartzSynthesis of Aligned Nanotubes on Sapphire Quartz
Gas in
Gas out
Sapphire with catalyst
Substrate Sapphire quartzCatalyst FerritinTemperature 900degCGas flow rate
CH4 2000 sccmC2H4 10 sccmH2 800 sccm
Generation IIFull Wafer Production
Generation IIFull Wafer Production
50 μm
2 0
1 5
1 0
5N
umbe
r
2 01 0D iam e te r (nm)500 nm
134 plusmn 030 nm
1 All nanotubes grow normal to the c axis on a-plane sapphire2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin11 All nanotubes grow normal to the c axis on aAll nanotubes grow normal to the c axis on a--plane sapphireplane sapphire2 Narrow diameter distribution of 2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin
c axis
Aligned Nanotubes Grown on a-Plane SapphireAligned Nanotubes Grown on a-Plane Sapphire
Zhou et al JACS 127 5294 (2005)
Zhou Zhou et alet al Nano Letters Nano Letters (2006)(2006)(Top ten hot articles in 2006)
High density SWNTsUp to 40 nanotubes μmInter-nanotube spacing ~ 25 nm
Low density SWNTs
Control of Nanotube DensityControl of Nanotube Density
Zhou et al JACS 127 5294 (2005) Zhou Zhou et alet al Nano Letters (2006) Nano Letters (2006)
a-plane
Red spheres oxygen atomsBlue spheres aluminum atomsPurple plane a-plane orientation
Hypothetic Schematic Diagram of SWNT on a-Plane SapphireHypothetic Schematic Diagram of SWNT on a-Plane Sapphire
Calculation of Lennard-Jones Potential Calculation of Lennard-Jones Potential
sumsum⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
minusminus⎟
⎟
⎠
⎞
⎜⎜
⎝
⎛
minus+
⎥⎥
⎦
⎤
⎢⎢
⎣
⎡
⎟⎟⎠
⎞⎜⎜⎝
⎛
minusminus⎟
⎟⎠
⎞⎜⎜⎝
⎛
minus=
j j
CAl
j
CAlCAl
i i
CO
i
COCO rrrrrrrr
rU
612612
44)( vvvvvvvvv σσ
εσσ
ε
a carbon atom and oxygen atoms in sapphire
a carbon atom and oxygen atoms in sapphire
a carbon atom and Al atoms in sapphire
a carbon atom and Al atoms in sapphire
Interaction between
Interaction between
C-plane C-plane a-plane a-plane
Potential wellPotential wellZhou Zhou et alet al JPCC JPCC 112 15929 (200(20088))
Synthesis of Nanotubes with Controlled Orientations and Positions
Synthesis of Nanotubes with Controlled Orientations and Positions
Catalyst
Photo Resist
QuartzSapphire
Catalyst Island
Aligned NanotubesMetal Electrode
SD
G
Dielectric Layer
3-10 nanotubes microm
Aligned Nanotubes on Quartz Using Patterned CatalystAligned Nanotubes on Quartz Using Patterned Catalystcatalyst
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
(a)
Poly Si Gate
Gate Oxide
SourceDrain Electrode
(b)
NanotubeGate Dielectric
Gate
SourceDrain Electrode
Comparison between Silicon-on-insulator (SOI) and Nanotube-on-Insulator (NOI)
Comparison between SiliconComparison between Silicon--onon--insulator (SOI) and insulator (SOI) and NanotubeNanotube--onon--Insulator (NOI)Insulator (NOI)
SOISOISOI NOINOINOI
Common Features1 Active material (Si or SWNT) is all over the surface2 Many devices can be patterned anywhere on the substrate3 Unwanted silicon or SWNTs can be removed via etching4 SOI and NOI offer minimized parasitic capacitance faster switching speed
and lower dynamic power consumption
Common FeaturesCommon Features11 Active material (Si or SWNT) is all over the surfaceActive material (Si or SWNT) is all over the surface22 Many devices can be patterned anywhere on the substrateMany devices can be patterned anywhere on the substrate33 Unwanted silicon or Unwanted silicon or SWNTsSWNTs can be removed via etchingcan be removed via etching44 SOI and NOI offer minimized parasitic capacitance faster switchSOI and NOI offer minimized parasitic capacitance faster switching speed ing speed
and lower dynamic power consumptionand lower dynamic power consumption Zhou et al Nano Letters (2006)
a-Sapphire
Wafer-Scale Aligned Nanotube SynthesisWafer-Scale Aligned Nanotube Synthesis
1200
1000
800
600
400
200
Tem
pera
ture
200150100500
Time (min)
Growth Annealing
Key meticulous temperature control amp uniform growth
1μm
Quartz 1000
800
600
400
200Tem
pera
ture
6004002000
Time (min)
Growth Annealing
1μm
4 inch substrate
Gas in
Gas out
Quartz or Sapphire with patterned
catalyst
9 feet-long growth furnace with three-zone
Wafer-Scale CNT TransferWafer-Scale CNT TransferTransfer fullTransfer full--wafer of wafer of CNTsCNTs from quartz growth substrate to SiOfrom quartz growth substrate to SiO22Si fabrication Si fabrication
substrate substrate allows largeallows large--scale integrationscale integration
Nano Lett 9 189ndash197 20094
Wafer-Scale Aligned Nanotube Device FabricationWafer-Scale Aligned Nanotube Device Fabrication
Back-Gated Submicron TransistorsBack-Gated Submicron Transistors
Back-gated transistors
1 microm
L = 1 microm
1 microm
L = 075 microm
1 microm
L = 05 microm
I-Vg curves Channel length dependence
-120
-100
-80
-60
-40
-20
0
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
-60
-40
-20
0
I ds (μ
Α)
-1500Vds (V)
-1 V
-08 V
-06 V
-04 V
-02 V
Vg from -8V to 8V
15
10
05
I ds (m
A)
-10 -5 0 5 10Vg (V)
L = 05 microm L = 075 microm L = 1 microm L = 2 microm L = 5 microm L = 10 microm L = 20 microm
80
60
40
20
gm
(μ S
)
5 6 7 81
2 3 4 5 6 7 810
2
L(μm)
2
4
6810-6
2
4
6810-5
I DW
(mA
microm
) gm
Ion Ioff
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
My Research
Nanoelectronicsbull Nanoscale transistors bull Nanoscale memoriesbull Circuits
Nanobiotechnologybull Biosensingbull Nano therapybull Drug delivery
Nano Materials
bull Carbon nanotubesbull NanowiresbullGraphene
oxLDLantibodyElectrode
PEIPEGNanowireNanotube
Si Substrate
SiO2
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Original MotivationMoorersquos Law
Original MotivationMoorersquos Law
1950 1970 1990 2010 2030
1 m
1 cm
Year
VLSI
Integratedcircuits
Transistor
Vacuum valves
Molecular dimensions
1 μm
10 nm
1 Α
Device size
From Intel
Si Substrate
Metal Gate
High-kTri-Gate
S
G
D
III-V
S
Carbon Nanotube FET
50 nm35 nm
30 nm
SiGe SD
Strained Silicon
Future options subject to research amp change
SiGe SD
Strained Silicon
90 nm65 nm
45 nm32 nm
20032005
20072009
2011+
Technology Generation
Source Intel
20 nm 10 nm
5 nm5 nm
5 nm
Nanowire
Manufacturing Development Research
Transistor Research
Research OptionsHigh-K amp Metal GateNon-planar TrigateIII-V CNT NW
CNT is a tubular form of carbon with diameter as small as 1 nm Length few nm to cm
CNT is configurationally equivalent to a two dimensional graphenesheet rolled into a tube
CNT exhibits1 Carrier mobility ~ 100000 cm2Vs2 Youngrsquos modulus over 1 Tera
Pascal as stiff as diamond3 Tensile strength ~ 200 GPa
Zigzag
Armchair
Chiral
MOLECULAR STRUCTUREMOLECULAR STRUCTURE
CNT can be metallic or semiconducting depending on chirality
Benchmarking CNT FETsBenchmarking CNT FETs
1
10
100
1000
10000
100000
130 90 65 45 22
Technology Node (nm)
Nor
mal
ized
FO
A
26X25X
28X 27X
Intrinsic CNT
MOS CNT FET
Band-edge SB CNTMidgap SB CNT
5000X
60X
50X20X
Si MOSFET
Source Ali Keshavarzi Intel
Nanotube Transistor ResearchNanotube Transistor ResearchGate
8nm HfO2
SiO2
p++ Si
PdPd CNT
Javey et al Nano Letters 4 1319 2004Delft Tans et al Nature 393 49 1998
Many people have studied individual nanotube transistors however the challenge is to integrate nanotube devices
Many people have studied individual nanotube transistors however the challenge is to integrate nanotube devices
Appenzeller et al PRL 93 19 2005
Drain
SourceGate
DrainSourceGate
Sapphire Substrate
GateOxide
Liu et al Nano Letters 6 34 2006
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Traditional approach On-Site Synthesis of Single-Walled Carbon Nanotubes
Traditional approach On-Site Synthesis of Single-Walled Carbon Nanotubes
SiSiO2
PMMA
Catalyst
CH4nanotube
Catalyst island
900 ordmC900 ordmC
metal electrode
H Dai et al Nature 395 878 (1998)
Infrastructure Nanotube CVD Generation IInfrastructure Nanotube CVD Generation I
1 μm
1 μm
26 nm in diameter
10 nm in diameter
High-quality nanotubes can be grown at specific positions
-60
-50
-40
-30
-20
-10
0
I DS(
nA)
-10-08-06-04-0200VDS(V)
Vg -4 V
0 V
2 V
6 V
Nanotube transistor can be easily produced
Si back gate
SiO2
S D
Integrated Nanotube SystemsComplementary Carbon Nanotube Inverter
Integrated Nanotube SystemsComplementary Carbon Nanotube Inverter
Carbon Nanotube Field-Effect Inverters X Liu R Lee J Han C Zhou Appl Phys Lett 79 3329 (2001)
One of the first integrated systems made of carbon nanotubes
Si back gate
K
Vin
Vout
VDD GND
p-type CNT n-type CNT
60
40
20
0
I DS(
nA)
-4 -2 0 2 4Vg(V)
VDS=10 mV
P type MOSFET12
8
4
0
I DS (
nA)
-4 -2 0 2 4Vg (V)
VDS=10 mV
N type MOSFET25
20
15
10
05
00
Vou
t(V)
252015100500Vin(V)
VDD=29 V
Vin Vout
0 V
VDD
p
n
Integrated Nanotube SystemsRing Oscillators Demonstrated by Avouris et al
Integrated Nanotube SystemsRing Oscillators Demonstrated by Avouris et al
Ph Avouris et al Science 311 1735 (2006)
Is there a way to assemble large quantities of nanotube devices
State-of-the-art of nanotube integration
Aligned Nanotubes for Devices and Circuits Aligned Nanotubes for Devices and Circuits
-- Project Mission Project Mission We want to tackle the challenging issue of We want to tackle the challenging issue of nanotube nanotube assembly and integrationassembly and integration
We want to grow carbon nanotubes withWe want to grow carbon nanotubes withControlled orientation (achieved by using Controlled orientation (achieved by using sapphire and quartz) sapphire and quartz) Controlled position (achieved) Controlled position (achieved) Controlled density (achieved) Controlled density (achieved) Controlled diameter (ongoing)Controlled diameter (ongoing)Controlled Controlled chiralitychirality (ongoing)(ongoing)
-- Our Approach Our Approach A novel nanotubeA novel nanotube--onon--insulator (NOI) insulator (NOI) approach based on approach based on aligned nanotubesaligned nanotubes for for integrated nanotube circuitsintegrated nanotube circuits Nanotube
devicesNanotube
circuits
Quartz SubstrateCatalyst Particle
Quartz Substrate
Nanotube
One of the first to grow aligned nanotubes on sapphireOne of the first to grow aligned nanotubes on sapphireJ of Am Chem Soc 127 5294 J of Am Chem Soc 127 5294 -- 5295 (2005) 5295 (2005)
The first to make aligned nanotube transistorsThe first to make aligned nanotube transistorsNano Letters 6 34Nano Letters 6 34--39 (2006)39 (2006)Reported by Reported by Scientific AmericanScientific American (April 2006 P16) (April 2006 P16)
The first to demonstrate waferThe first to demonstrate wafer--scale processing of aligned scale processing of aligned nanotube devices and circuitsnanotube devices and circuits
Logic circuits (CMOS inverter NAND NOR)Logic circuits (CMOS inverter NAND NOR)
The first to make transparent nanotube devicesThe first to make transparent nanotube devicesACS Nano in press (2008)ACS Nano in press (2008)
Chip
1
2
3
4
5
Our Achievements on Aligned Single-Walled NanotubesOur Achievements on Aligned SingleOur Achievements on Aligned Single--Walled NanotubesWalled Nanotubes
Synthesis of Aligned Nanotubes on Sapphire QuartzSynthesis of Aligned Nanotubes on Sapphire Quartz
Gas in
Gas out
Sapphire with catalyst
Substrate Sapphire quartzCatalyst FerritinTemperature 900degCGas flow rate
CH4 2000 sccmC2H4 10 sccmH2 800 sccm
Generation IIFull Wafer Production
Generation IIFull Wafer Production
50 μm
2 0
1 5
1 0
5N
umbe
r
2 01 0D iam e te r (nm)500 nm
134 plusmn 030 nm
1 All nanotubes grow normal to the c axis on a-plane sapphire2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin11 All nanotubes grow normal to the c axis on aAll nanotubes grow normal to the c axis on a--plane sapphireplane sapphire2 Narrow diameter distribution of 2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin
c axis
Aligned Nanotubes Grown on a-Plane SapphireAligned Nanotubes Grown on a-Plane Sapphire
Zhou et al JACS 127 5294 (2005)
Zhou Zhou et alet al Nano Letters Nano Letters (2006)(2006)(Top ten hot articles in 2006)
High density SWNTsUp to 40 nanotubes μmInter-nanotube spacing ~ 25 nm
Low density SWNTs
Control of Nanotube DensityControl of Nanotube Density
Zhou et al JACS 127 5294 (2005) Zhou Zhou et alet al Nano Letters (2006) Nano Letters (2006)
a-plane
Red spheres oxygen atomsBlue spheres aluminum atomsPurple plane a-plane orientation
Hypothetic Schematic Diagram of SWNT on a-Plane SapphireHypothetic Schematic Diagram of SWNT on a-Plane Sapphire
Calculation of Lennard-Jones Potential Calculation of Lennard-Jones Potential
sumsum⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
minusminus⎟
⎟
⎠
⎞
⎜⎜
⎝
⎛
minus+
⎥⎥
⎦
⎤
⎢⎢
⎣
⎡
⎟⎟⎠
⎞⎜⎜⎝
⎛
minusminus⎟
⎟⎠
⎞⎜⎜⎝
⎛
minus=
j j
CAl
j
CAlCAl
i i
CO
i
COCO rrrrrrrr
rU
612612
44)( vvvvvvvvv σσ
εσσ
ε
a carbon atom and oxygen atoms in sapphire
a carbon atom and oxygen atoms in sapphire
a carbon atom and Al atoms in sapphire
a carbon atom and Al atoms in sapphire
Interaction between
Interaction between
C-plane C-plane a-plane a-plane
Potential wellPotential wellZhou Zhou et alet al JPCC JPCC 112 15929 (200(20088))
Synthesis of Nanotubes with Controlled Orientations and Positions
Synthesis of Nanotubes with Controlled Orientations and Positions
Catalyst
Photo Resist
QuartzSapphire
Catalyst Island
Aligned NanotubesMetal Electrode
SD
G
Dielectric Layer
3-10 nanotubes microm
Aligned Nanotubes on Quartz Using Patterned CatalystAligned Nanotubes on Quartz Using Patterned Catalystcatalyst
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
(a)
Poly Si Gate
Gate Oxide
SourceDrain Electrode
(b)
NanotubeGate Dielectric
Gate
SourceDrain Electrode
Comparison between Silicon-on-insulator (SOI) and Nanotube-on-Insulator (NOI)
Comparison between SiliconComparison between Silicon--onon--insulator (SOI) and insulator (SOI) and NanotubeNanotube--onon--Insulator (NOI)Insulator (NOI)
SOISOISOI NOINOINOI
Common Features1 Active material (Si or SWNT) is all over the surface2 Many devices can be patterned anywhere on the substrate3 Unwanted silicon or SWNTs can be removed via etching4 SOI and NOI offer minimized parasitic capacitance faster switching speed
and lower dynamic power consumption
Common FeaturesCommon Features11 Active material (Si or SWNT) is all over the surfaceActive material (Si or SWNT) is all over the surface22 Many devices can be patterned anywhere on the substrateMany devices can be patterned anywhere on the substrate33 Unwanted silicon or Unwanted silicon or SWNTsSWNTs can be removed via etchingcan be removed via etching44 SOI and NOI offer minimized parasitic capacitance faster switchSOI and NOI offer minimized parasitic capacitance faster switching speed ing speed
and lower dynamic power consumptionand lower dynamic power consumption Zhou et al Nano Letters (2006)
a-Sapphire
Wafer-Scale Aligned Nanotube SynthesisWafer-Scale Aligned Nanotube Synthesis
1200
1000
800
600
400
200
Tem
pera
ture
200150100500
Time (min)
Growth Annealing
Key meticulous temperature control amp uniform growth
1μm
Quartz 1000
800
600
400
200Tem
pera
ture
6004002000
Time (min)
Growth Annealing
1μm
4 inch substrate
Gas in
Gas out
Quartz or Sapphire with patterned
catalyst
9 feet-long growth furnace with three-zone
Wafer-Scale CNT TransferWafer-Scale CNT TransferTransfer fullTransfer full--wafer of wafer of CNTsCNTs from quartz growth substrate to SiOfrom quartz growth substrate to SiO22Si fabrication Si fabrication
substrate substrate allows largeallows large--scale integrationscale integration
Nano Lett 9 189ndash197 20094
Wafer-Scale Aligned Nanotube Device FabricationWafer-Scale Aligned Nanotube Device Fabrication
Back-Gated Submicron TransistorsBack-Gated Submicron Transistors
Back-gated transistors
1 microm
L = 1 microm
1 microm
L = 075 microm
1 microm
L = 05 microm
I-Vg curves Channel length dependence
-120
-100
-80
-60
-40
-20
0
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
-60
-40
-20
0
I ds (μ
Α)
-1500Vds (V)
-1 V
-08 V
-06 V
-04 V
-02 V
Vg from -8V to 8V
15
10
05
I ds (m
A)
-10 -5 0 5 10Vg (V)
L = 05 microm L = 075 microm L = 1 microm L = 2 microm L = 5 microm L = 10 microm L = 20 microm
80
60
40
20
gm
(μ S
)
5 6 7 81
2 3 4 5 6 7 810
2
L(μm)
2
4
6810-6
2
4
6810-5
I DW
(mA
microm
) gm
Ion Ioff
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Original MotivationMoorersquos Law
Original MotivationMoorersquos Law
1950 1970 1990 2010 2030
1 m
1 cm
Year
VLSI
Integratedcircuits
Transistor
Vacuum valves
Molecular dimensions
1 μm
10 nm
1 Α
Device size
From Intel
Si Substrate
Metal Gate
High-kTri-Gate
S
G
D
III-V
S
Carbon Nanotube FET
50 nm35 nm
30 nm
SiGe SD
Strained Silicon
Future options subject to research amp change
SiGe SD
Strained Silicon
90 nm65 nm
45 nm32 nm
20032005
20072009
2011+
Technology Generation
Source Intel
20 nm 10 nm
5 nm5 nm
5 nm
Nanowire
Manufacturing Development Research
Transistor Research
Research OptionsHigh-K amp Metal GateNon-planar TrigateIII-V CNT NW
CNT is a tubular form of carbon with diameter as small as 1 nm Length few nm to cm
CNT is configurationally equivalent to a two dimensional graphenesheet rolled into a tube
CNT exhibits1 Carrier mobility ~ 100000 cm2Vs2 Youngrsquos modulus over 1 Tera
Pascal as stiff as diamond3 Tensile strength ~ 200 GPa
Zigzag
Armchair
Chiral
MOLECULAR STRUCTUREMOLECULAR STRUCTURE
CNT can be metallic or semiconducting depending on chirality
Benchmarking CNT FETsBenchmarking CNT FETs
1
10
100
1000
10000
100000
130 90 65 45 22
Technology Node (nm)
Nor
mal
ized
FO
A
26X25X
28X 27X
Intrinsic CNT
MOS CNT FET
Band-edge SB CNTMidgap SB CNT
5000X
60X
50X20X
Si MOSFET
Source Ali Keshavarzi Intel
Nanotube Transistor ResearchNanotube Transistor ResearchGate
8nm HfO2
SiO2
p++ Si
PdPd CNT
Javey et al Nano Letters 4 1319 2004Delft Tans et al Nature 393 49 1998
Many people have studied individual nanotube transistors however the challenge is to integrate nanotube devices
Many people have studied individual nanotube transistors however the challenge is to integrate nanotube devices
Appenzeller et al PRL 93 19 2005
Drain
SourceGate
DrainSourceGate
Sapphire Substrate
GateOxide
Liu et al Nano Letters 6 34 2006
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Traditional approach On-Site Synthesis of Single-Walled Carbon Nanotubes
Traditional approach On-Site Synthesis of Single-Walled Carbon Nanotubes
SiSiO2
PMMA
Catalyst
CH4nanotube
Catalyst island
900 ordmC900 ordmC
metal electrode
H Dai et al Nature 395 878 (1998)
Infrastructure Nanotube CVD Generation IInfrastructure Nanotube CVD Generation I
1 μm
1 μm
26 nm in diameter
10 nm in diameter
High-quality nanotubes can be grown at specific positions
-60
-50
-40
-30
-20
-10
0
I DS(
nA)
-10-08-06-04-0200VDS(V)
Vg -4 V
0 V
2 V
6 V
Nanotube transistor can be easily produced
Si back gate
SiO2
S D
Integrated Nanotube SystemsComplementary Carbon Nanotube Inverter
Integrated Nanotube SystemsComplementary Carbon Nanotube Inverter
Carbon Nanotube Field-Effect Inverters X Liu R Lee J Han C Zhou Appl Phys Lett 79 3329 (2001)
One of the first integrated systems made of carbon nanotubes
Si back gate
K
Vin
Vout
VDD GND
p-type CNT n-type CNT
60
40
20
0
I DS(
nA)
-4 -2 0 2 4Vg(V)
VDS=10 mV
P type MOSFET12
8
4
0
I DS (
nA)
-4 -2 0 2 4Vg (V)
VDS=10 mV
N type MOSFET25
20
15
10
05
00
Vou
t(V)
252015100500Vin(V)
VDD=29 V
Vin Vout
0 V
VDD
p
n
Integrated Nanotube SystemsRing Oscillators Demonstrated by Avouris et al
Integrated Nanotube SystemsRing Oscillators Demonstrated by Avouris et al
Ph Avouris et al Science 311 1735 (2006)
Is there a way to assemble large quantities of nanotube devices
State-of-the-art of nanotube integration
Aligned Nanotubes for Devices and Circuits Aligned Nanotubes for Devices and Circuits
-- Project Mission Project Mission We want to tackle the challenging issue of We want to tackle the challenging issue of nanotube nanotube assembly and integrationassembly and integration
We want to grow carbon nanotubes withWe want to grow carbon nanotubes withControlled orientation (achieved by using Controlled orientation (achieved by using sapphire and quartz) sapphire and quartz) Controlled position (achieved) Controlled position (achieved) Controlled density (achieved) Controlled density (achieved) Controlled diameter (ongoing)Controlled diameter (ongoing)Controlled Controlled chiralitychirality (ongoing)(ongoing)
-- Our Approach Our Approach A novel nanotubeA novel nanotube--onon--insulator (NOI) insulator (NOI) approach based on approach based on aligned nanotubesaligned nanotubes for for integrated nanotube circuitsintegrated nanotube circuits Nanotube
devicesNanotube
circuits
Quartz SubstrateCatalyst Particle
Quartz Substrate
Nanotube
One of the first to grow aligned nanotubes on sapphireOne of the first to grow aligned nanotubes on sapphireJ of Am Chem Soc 127 5294 J of Am Chem Soc 127 5294 -- 5295 (2005) 5295 (2005)
The first to make aligned nanotube transistorsThe first to make aligned nanotube transistorsNano Letters 6 34Nano Letters 6 34--39 (2006)39 (2006)Reported by Reported by Scientific AmericanScientific American (April 2006 P16) (April 2006 P16)
The first to demonstrate waferThe first to demonstrate wafer--scale processing of aligned scale processing of aligned nanotube devices and circuitsnanotube devices and circuits
Logic circuits (CMOS inverter NAND NOR)Logic circuits (CMOS inverter NAND NOR)
The first to make transparent nanotube devicesThe first to make transparent nanotube devicesACS Nano in press (2008)ACS Nano in press (2008)
Chip
1
2
3
4
5
Our Achievements on Aligned Single-Walled NanotubesOur Achievements on Aligned SingleOur Achievements on Aligned Single--Walled NanotubesWalled Nanotubes
Synthesis of Aligned Nanotubes on Sapphire QuartzSynthesis of Aligned Nanotubes on Sapphire Quartz
Gas in
Gas out
Sapphire with catalyst
Substrate Sapphire quartzCatalyst FerritinTemperature 900degCGas flow rate
CH4 2000 sccmC2H4 10 sccmH2 800 sccm
Generation IIFull Wafer Production
Generation IIFull Wafer Production
50 μm
2 0
1 5
1 0
5N
umbe
r
2 01 0D iam e te r (nm)500 nm
134 plusmn 030 nm
1 All nanotubes grow normal to the c axis on a-plane sapphire2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin11 All nanotubes grow normal to the c axis on aAll nanotubes grow normal to the c axis on a--plane sapphireplane sapphire2 Narrow diameter distribution of 2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin
c axis
Aligned Nanotubes Grown on a-Plane SapphireAligned Nanotubes Grown on a-Plane Sapphire
Zhou et al JACS 127 5294 (2005)
Zhou Zhou et alet al Nano Letters Nano Letters (2006)(2006)(Top ten hot articles in 2006)
High density SWNTsUp to 40 nanotubes μmInter-nanotube spacing ~ 25 nm
Low density SWNTs
Control of Nanotube DensityControl of Nanotube Density
Zhou et al JACS 127 5294 (2005) Zhou Zhou et alet al Nano Letters (2006) Nano Letters (2006)
a-plane
Red spheres oxygen atomsBlue spheres aluminum atomsPurple plane a-plane orientation
Hypothetic Schematic Diagram of SWNT on a-Plane SapphireHypothetic Schematic Diagram of SWNT on a-Plane Sapphire
Calculation of Lennard-Jones Potential Calculation of Lennard-Jones Potential
sumsum⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
minusminus⎟
⎟
⎠
⎞
⎜⎜
⎝
⎛
minus+
⎥⎥
⎦
⎤
⎢⎢
⎣
⎡
⎟⎟⎠
⎞⎜⎜⎝
⎛
minusminus⎟
⎟⎠
⎞⎜⎜⎝
⎛
minus=
j j
CAl
j
CAlCAl
i i
CO
i
COCO rrrrrrrr
rU
612612
44)( vvvvvvvvv σσ
εσσ
ε
a carbon atom and oxygen atoms in sapphire
a carbon atom and oxygen atoms in sapphire
a carbon atom and Al atoms in sapphire
a carbon atom and Al atoms in sapphire
Interaction between
Interaction between
C-plane C-plane a-plane a-plane
Potential wellPotential wellZhou Zhou et alet al JPCC JPCC 112 15929 (200(20088))
Synthesis of Nanotubes with Controlled Orientations and Positions
Synthesis of Nanotubes with Controlled Orientations and Positions
Catalyst
Photo Resist
QuartzSapphire
Catalyst Island
Aligned NanotubesMetal Electrode
SD
G
Dielectric Layer
3-10 nanotubes microm
Aligned Nanotubes on Quartz Using Patterned CatalystAligned Nanotubes on Quartz Using Patterned Catalystcatalyst
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
(a)
Poly Si Gate
Gate Oxide
SourceDrain Electrode
(b)
NanotubeGate Dielectric
Gate
SourceDrain Electrode
Comparison between Silicon-on-insulator (SOI) and Nanotube-on-Insulator (NOI)
Comparison between SiliconComparison between Silicon--onon--insulator (SOI) and insulator (SOI) and NanotubeNanotube--onon--Insulator (NOI)Insulator (NOI)
SOISOISOI NOINOINOI
Common Features1 Active material (Si or SWNT) is all over the surface2 Many devices can be patterned anywhere on the substrate3 Unwanted silicon or SWNTs can be removed via etching4 SOI and NOI offer minimized parasitic capacitance faster switching speed
and lower dynamic power consumption
Common FeaturesCommon Features11 Active material (Si or SWNT) is all over the surfaceActive material (Si or SWNT) is all over the surface22 Many devices can be patterned anywhere on the substrateMany devices can be patterned anywhere on the substrate33 Unwanted silicon or Unwanted silicon or SWNTsSWNTs can be removed via etchingcan be removed via etching44 SOI and NOI offer minimized parasitic capacitance faster switchSOI and NOI offer minimized parasitic capacitance faster switching speed ing speed
and lower dynamic power consumptionand lower dynamic power consumption Zhou et al Nano Letters (2006)
a-Sapphire
Wafer-Scale Aligned Nanotube SynthesisWafer-Scale Aligned Nanotube Synthesis
1200
1000
800
600
400
200
Tem
pera
ture
200150100500
Time (min)
Growth Annealing
Key meticulous temperature control amp uniform growth
1μm
Quartz 1000
800
600
400
200Tem
pera
ture
6004002000
Time (min)
Growth Annealing
1μm
4 inch substrate
Gas in
Gas out
Quartz or Sapphire with patterned
catalyst
9 feet-long growth furnace with three-zone
Wafer-Scale CNT TransferWafer-Scale CNT TransferTransfer fullTransfer full--wafer of wafer of CNTsCNTs from quartz growth substrate to SiOfrom quartz growth substrate to SiO22Si fabrication Si fabrication
substrate substrate allows largeallows large--scale integrationscale integration
Nano Lett 9 189ndash197 20094
Wafer-Scale Aligned Nanotube Device FabricationWafer-Scale Aligned Nanotube Device Fabrication
Back-Gated Submicron TransistorsBack-Gated Submicron Transistors
Back-gated transistors
1 microm
L = 1 microm
1 microm
L = 075 microm
1 microm
L = 05 microm
I-Vg curves Channel length dependence
-120
-100
-80
-60
-40
-20
0
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
-60
-40
-20
0
I ds (μ
Α)
-1500Vds (V)
-1 V
-08 V
-06 V
-04 V
-02 V
Vg from -8V to 8V
15
10
05
I ds (m
A)
-10 -5 0 5 10Vg (V)
L = 05 microm L = 075 microm L = 1 microm L = 2 microm L = 5 microm L = 10 microm L = 20 microm
80
60
40
20
gm
(μ S
)
5 6 7 81
2 3 4 5 6 7 810
2
L(μm)
2
4
6810-6
2
4
6810-5
I DW
(mA
microm
) gm
Ion Ioff
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Original MotivationMoorersquos Law
Original MotivationMoorersquos Law
1950 1970 1990 2010 2030
1 m
1 cm
Year
VLSI
Integratedcircuits
Transistor
Vacuum valves
Molecular dimensions
1 μm
10 nm
1 Α
Device size
From Intel
Si Substrate
Metal Gate
High-kTri-Gate
S
G
D
III-V
S
Carbon Nanotube FET
50 nm35 nm
30 nm
SiGe SD
Strained Silicon
Future options subject to research amp change
SiGe SD
Strained Silicon
90 nm65 nm
45 nm32 nm
20032005
20072009
2011+
Technology Generation
Source Intel
20 nm 10 nm
5 nm5 nm
5 nm
Nanowire
Manufacturing Development Research
Transistor Research
Research OptionsHigh-K amp Metal GateNon-planar TrigateIII-V CNT NW
CNT is a tubular form of carbon with diameter as small as 1 nm Length few nm to cm
CNT is configurationally equivalent to a two dimensional graphenesheet rolled into a tube
CNT exhibits1 Carrier mobility ~ 100000 cm2Vs2 Youngrsquos modulus over 1 Tera
Pascal as stiff as diamond3 Tensile strength ~ 200 GPa
Zigzag
Armchair
Chiral
MOLECULAR STRUCTUREMOLECULAR STRUCTURE
CNT can be metallic or semiconducting depending on chirality
Benchmarking CNT FETsBenchmarking CNT FETs
1
10
100
1000
10000
100000
130 90 65 45 22
Technology Node (nm)
Nor
mal
ized
FO
A
26X25X
28X 27X
Intrinsic CNT
MOS CNT FET
Band-edge SB CNTMidgap SB CNT
5000X
60X
50X20X
Si MOSFET
Source Ali Keshavarzi Intel
Nanotube Transistor ResearchNanotube Transistor ResearchGate
8nm HfO2
SiO2
p++ Si
PdPd CNT
Javey et al Nano Letters 4 1319 2004Delft Tans et al Nature 393 49 1998
Many people have studied individual nanotube transistors however the challenge is to integrate nanotube devices
Many people have studied individual nanotube transistors however the challenge is to integrate nanotube devices
Appenzeller et al PRL 93 19 2005
Drain
SourceGate
DrainSourceGate
Sapphire Substrate
GateOxide
Liu et al Nano Letters 6 34 2006
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Traditional approach On-Site Synthesis of Single-Walled Carbon Nanotubes
Traditional approach On-Site Synthesis of Single-Walled Carbon Nanotubes
SiSiO2
PMMA
Catalyst
CH4nanotube
Catalyst island
900 ordmC900 ordmC
metal electrode
H Dai et al Nature 395 878 (1998)
Infrastructure Nanotube CVD Generation IInfrastructure Nanotube CVD Generation I
1 μm
1 μm
26 nm in diameter
10 nm in diameter
High-quality nanotubes can be grown at specific positions
-60
-50
-40
-30
-20
-10
0
I DS(
nA)
-10-08-06-04-0200VDS(V)
Vg -4 V
0 V
2 V
6 V
Nanotube transistor can be easily produced
Si back gate
SiO2
S D
Integrated Nanotube SystemsComplementary Carbon Nanotube Inverter
Integrated Nanotube SystemsComplementary Carbon Nanotube Inverter
Carbon Nanotube Field-Effect Inverters X Liu R Lee J Han C Zhou Appl Phys Lett 79 3329 (2001)
One of the first integrated systems made of carbon nanotubes
Si back gate
K
Vin
Vout
VDD GND
p-type CNT n-type CNT
60
40
20
0
I DS(
nA)
-4 -2 0 2 4Vg(V)
VDS=10 mV
P type MOSFET12
8
4
0
I DS (
nA)
-4 -2 0 2 4Vg (V)
VDS=10 mV
N type MOSFET25
20
15
10
05
00
Vou
t(V)
252015100500Vin(V)
VDD=29 V
Vin Vout
0 V
VDD
p
n
Integrated Nanotube SystemsRing Oscillators Demonstrated by Avouris et al
Integrated Nanotube SystemsRing Oscillators Demonstrated by Avouris et al
Ph Avouris et al Science 311 1735 (2006)
Is there a way to assemble large quantities of nanotube devices
State-of-the-art of nanotube integration
Aligned Nanotubes for Devices and Circuits Aligned Nanotubes for Devices and Circuits
-- Project Mission Project Mission We want to tackle the challenging issue of We want to tackle the challenging issue of nanotube nanotube assembly and integrationassembly and integration
We want to grow carbon nanotubes withWe want to grow carbon nanotubes withControlled orientation (achieved by using Controlled orientation (achieved by using sapphire and quartz) sapphire and quartz) Controlled position (achieved) Controlled position (achieved) Controlled density (achieved) Controlled density (achieved) Controlled diameter (ongoing)Controlled diameter (ongoing)Controlled Controlled chiralitychirality (ongoing)(ongoing)
-- Our Approach Our Approach A novel nanotubeA novel nanotube--onon--insulator (NOI) insulator (NOI) approach based on approach based on aligned nanotubesaligned nanotubes for for integrated nanotube circuitsintegrated nanotube circuits Nanotube
devicesNanotube
circuits
Quartz SubstrateCatalyst Particle
Quartz Substrate
Nanotube
One of the first to grow aligned nanotubes on sapphireOne of the first to grow aligned nanotubes on sapphireJ of Am Chem Soc 127 5294 J of Am Chem Soc 127 5294 -- 5295 (2005) 5295 (2005)
The first to make aligned nanotube transistorsThe first to make aligned nanotube transistorsNano Letters 6 34Nano Letters 6 34--39 (2006)39 (2006)Reported by Reported by Scientific AmericanScientific American (April 2006 P16) (April 2006 P16)
The first to demonstrate waferThe first to demonstrate wafer--scale processing of aligned scale processing of aligned nanotube devices and circuitsnanotube devices and circuits
Logic circuits (CMOS inverter NAND NOR)Logic circuits (CMOS inverter NAND NOR)
The first to make transparent nanotube devicesThe first to make transparent nanotube devicesACS Nano in press (2008)ACS Nano in press (2008)
Chip
1
2
3
4
5
Our Achievements on Aligned Single-Walled NanotubesOur Achievements on Aligned SingleOur Achievements on Aligned Single--Walled NanotubesWalled Nanotubes
Synthesis of Aligned Nanotubes on Sapphire QuartzSynthesis of Aligned Nanotubes on Sapphire Quartz
Gas in
Gas out
Sapphire with catalyst
Substrate Sapphire quartzCatalyst FerritinTemperature 900degCGas flow rate
CH4 2000 sccmC2H4 10 sccmH2 800 sccm
Generation IIFull Wafer Production
Generation IIFull Wafer Production
50 μm
2 0
1 5
1 0
5N
umbe
r
2 01 0D iam e te r (nm)500 nm
134 plusmn 030 nm
1 All nanotubes grow normal to the c axis on a-plane sapphire2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin11 All nanotubes grow normal to the c axis on aAll nanotubes grow normal to the c axis on a--plane sapphireplane sapphire2 Narrow diameter distribution of 2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin
c axis
Aligned Nanotubes Grown on a-Plane SapphireAligned Nanotubes Grown on a-Plane Sapphire
Zhou et al JACS 127 5294 (2005)
Zhou Zhou et alet al Nano Letters Nano Letters (2006)(2006)(Top ten hot articles in 2006)
High density SWNTsUp to 40 nanotubes μmInter-nanotube spacing ~ 25 nm
Low density SWNTs
Control of Nanotube DensityControl of Nanotube Density
Zhou et al JACS 127 5294 (2005) Zhou Zhou et alet al Nano Letters (2006) Nano Letters (2006)
a-plane
Red spheres oxygen atomsBlue spheres aluminum atomsPurple plane a-plane orientation
Hypothetic Schematic Diagram of SWNT on a-Plane SapphireHypothetic Schematic Diagram of SWNT on a-Plane Sapphire
Calculation of Lennard-Jones Potential Calculation of Lennard-Jones Potential
sumsum⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
minusminus⎟
⎟
⎠
⎞
⎜⎜
⎝
⎛
minus+
⎥⎥
⎦
⎤
⎢⎢
⎣
⎡
⎟⎟⎠
⎞⎜⎜⎝
⎛
minusminus⎟
⎟⎠
⎞⎜⎜⎝
⎛
minus=
j j
CAl
j
CAlCAl
i i
CO
i
COCO rrrrrrrr
rU
612612
44)( vvvvvvvvv σσ
εσσ
ε
a carbon atom and oxygen atoms in sapphire
a carbon atom and oxygen atoms in sapphire
a carbon atom and Al atoms in sapphire
a carbon atom and Al atoms in sapphire
Interaction between
Interaction between
C-plane C-plane a-plane a-plane
Potential wellPotential wellZhou Zhou et alet al JPCC JPCC 112 15929 (200(20088))
Synthesis of Nanotubes with Controlled Orientations and Positions
Synthesis of Nanotubes with Controlled Orientations and Positions
Catalyst
Photo Resist
QuartzSapphire
Catalyst Island
Aligned NanotubesMetal Electrode
SD
G
Dielectric Layer
3-10 nanotubes microm
Aligned Nanotubes on Quartz Using Patterned CatalystAligned Nanotubes on Quartz Using Patterned Catalystcatalyst
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
(a)
Poly Si Gate
Gate Oxide
SourceDrain Electrode
(b)
NanotubeGate Dielectric
Gate
SourceDrain Electrode
Comparison between Silicon-on-insulator (SOI) and Nanotube-on-Insulator (NOI)
Comparison between SiliconComparison between Silicon--onon--insulator (SOI) and insulator (SOI) and NanotubeNanotube--onon--Insulator (NOI)Insulator (NOI)
SOISOISOI NOINOINOI
Common Features1 Active material (Si or SWNT) is all over the surface2 Many devices can be patterned anywhere on the substrate3 Unwanted silicon or SWNTs can be removed via etching4 SOI and NOI offer minimized parasitic capacitance faster switching speed
and lower dynamic power consumption
Common FeaturesCommon Features11 Active material (Si or SWNT) is all over the surfaceActive material (Si or SWNT) is all over the surface22 Many devices can be patterned anywhere on the substrateMany devices can be patterned anywhere on the substrate33 Unwanted silicon or Unwanted silicon or SWNTsSWNTs can be removed via etchingcan be removed via etching44 SOI and NOI offer minimized parasitic capacitance faster switchSOI and NOI offer minimized parasitic capacitance faster switching speed ing speed
and lower dynamic power consumptionand lower dynamic power consumption Zhou et al Nano Letters (2006)
a-Sapphire
Wafer-Scale Aligned Nanotube SynthesisWafer-Scale Aligned Nanotube Synthesis
1200
1000
800
600
400
200
Tem
pera
ture
200150100500
Time (min)
Growth Annealing
Key meticulous temperature control amp uniform growth
1μm
Quartz 1000
800
600
400
200Tem
pera
ture
6004002000
Time (min)
Growth Annealing
1μm
4 inch substrate
Gas in
Gas out
Quartz or Sapphire with patterned
catalyst
9 feet-long growth furnace with three-zone
Wafer-Scale CNT TransferWafer-Scale CNT TransferTransfer fullTransfer full--wafer of wafer of CNTsCNTs from quartz growth substrate to SiOfrom quartz growth substrate to SiO22Si fabrication Si fabrication
substrate substrate allows largeallows large--scale integrationscale integration
Nano Lett 9 189ndash197 20094
Wafer-Scale Aligned Nanotube Device FabricationWafer-Scale Aligned Nanotube Device Fabrication
Back-Gated Submicron TransistorsBack-Gated Submicron Transistors
Back-gated transistors
1 microm
L = 1 microm
1 microm
L = 075 microm
1 microm
L = 05 microm
I-Vg curves Channel length dependence
-120
-100
-80
-60
-40
-20
0
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
-60
-40
-20
0
I ds (μ
Α)
-1500Vds (V)
-1 V
-08 V
-06 V
-04 V
-02 V
Vg from -8V to 8V
15
10
05
I ds (m
A)
-10 -5 0 5 10Vg (V)
L = 05 microm L = 075 microm L = 1 microm L = 2 microm L = 5 microm L = 10 microm L = 20 microm
80
60
40
20
gm
(μ S
)
5 6 7 81
2 3 4 5 6 7 810
2
L(μm)
2
4
6810-6
2
4
6810-5
I DW
(mA
microm
) gm
Ion Ioff
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Si Substrate
Metal Gate
High-kTri-Gate
S
G
D
III-V
S
Carbon Nanotube FET
50 nm35 nm
30 nm
SiGe SD
Strained Silicon
Future options subject to research amp change
SiGe SD
Strained Silicon
90 nm65 nm
45 nm32 nm
20032005
20072009
2011+
Technology Generation
Source Intel
20 nm 10 nm
5 nm5 nm
5 nm
Nanowire
Manufacturing Development Research
Transistor Research
Research OptionsHigh-K amp Metal GateNon-planar TrigateIII-V CNT NW
CNT is a tubular form of carbon with diameter as small as 1 nm Length few nm to cm
CNT is configurationally equivalent to a two dimensional graphenesheet rolled into a tube
CNT exhibits1 Carrier mobility ~ 100000 cm2Vs2 Youngrsquos modulus over 1 Tera
Pascal as stiff as diamond3 Tensile strength ~ 200 GPa
Zigzag
Armchair
Chiral
MOLECULAR STRUCTUREMOLECULAR STRUCTURE
CNT can be metallic or semiconducting depending on chirality
Benchmarking CNT FETsBenchmarking CNT FETs
1
10
100
1000
10000
100000
130 90 65 45 22
Technology Node (nm)
Nor
mal
ized
FO
A
26X25X
28X 27X
Intrinsic CNT
MOS CNT FET
Band-edge SB CNTMidgap SB CNT
5000X
60X
50X20X
Si MOSFET
Source Ali Keshavarzi Intel
Nanotube Transistor ResearchNanotube Transistor ResearchGate
8nm HfO2
SiO2
p++ Si
PdPd CNT
Javey et al Nano Letters 4 1319 2004Delft Tans et al Nature 393 49 1998
Many people have studied individual nanotube transistors however the challenge is to integrate nanotube devices
Many people have studied individual nanotube transistors however the challenge is to integrate nanotube devices
Appenzeller et al PRL 93 19 2005
Drain
SourceGate
DrainSourceGate
Sapphire Substrate
GateOxide
Liu et al Nano Letters 6 34 2006
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Traditional approach On-Site Synthesis of Single-Walled Carbon Nanotubes
Traditional approach On-Site Synthesis of Single-Walled Carbon Nanotubes
SiSiO2
PMMA
Catalyst
CH4nanotube
Catalyst island
900 ordmC900 ordmC
metal electrode
H Dai et al Nature 395 878 (1998)
Infrastructure Nanotube CVD Generation IInfrastructure Nanotube CVD Generation I
1 μm
1 μm
26 nm in diameter
10 nm in diameter
High-quality nanotubes can be grown at specific positions
-60
-50
-40
-30
-20
-10
0
I DS(
nA)
-10-08-06-04-0200VDS(V)
Vg -4 V
0 V
2 V
6 V
Nanotube transistor can be easily produced
Si back gate
SiO2
S D
Integrated Nanotube SystemsComplementary Carbon Nanotube Inverter
Integrated Nanotube SystemsComplementary Carbon Nanotube Inverter
Carbon Nanotube Field-Effect Inverters X Liu R Lee J Han C Zhou Appl Phys Lett 79 3329 (2001)
One of the first integrated systems made of carbon nanotubes
Si back gate
K
Vin
Vout
VDD GND
p-type CNT n-type CNT
60
40
20
0
I DS(
nA)
-4 -2 0 2 4Vg(V)
VDS=10 mV
P type MOSFET12
8
4
0
I DS (
nA)
-4 -2 0 2 4Vg (V)
VDS=10 mV
N type MOSFET25
20
15
10
05
00
Vou
t(V)
252015100500Vin(V)
VDD=29 V
Vin Vout
0 V
VDD
p
n
Integrated Nanotube SystemsRing Oscillators Demonstrated by Avouris et al
Integrated Nanotube SystemsRing Oscillators Demonstrated by Avouris et al
Ph Avouris et al Science 311 1735 (2006)
Is there a way to assemble large quantities of nanotube devices
State-of-the-art of nanotube integration
Aligned Nanotubes for Devices and Circuits Aligned Nanotubes for Devices and Circuits
-- Project Mission Project Mission We want to tackle the challenging issue of We want to tackle the challenging issue of nanotube nanotube assembly and integrationassembly and integration
We want to grow carbon nanotubes withWe want to grow carbon nanotubes withControlled orientation (achieved by using Controlled orientation (achieved by using sapphire and quartz) sapphire and quartz) Controlled position (achieved) Controlled position (achieved) Controlled density (achieved) Controlled density (achieved) Controlled diameter (ongoing)Controlled diameter (ongoing)Controlled Controlled chiralitychirality (ongoing)(ongoing)
-- Our Approach Our Approach A novel nanotubeA novel nanotube--onon--insulator (NOI) insulator (NOI) approach based on approach based on aligned nanotubesaligned nanotubes for for integrated nanotube circuitsintegrated nanotube circuits Nanotube
devicesNanotube
circuits
Quartz SubstrateCatalyst Particle
Quartz Substrate
Nanotube
One of the first to grow aligned nanotubes on sapphireOne of the first to grow aligned nanotubes on sapphireJ of Am Chem Soc 127 5294 J of Am Chem Soc 127 5294 -- 5295 (2005) 5295 (2005)
The first to make aligned nanotube transistorsThe first to make aligned nanotube transistorsNano Letters 6 34Nano Letters 6 34--39 (2006)39 (2006)Reported by Reported by Scientific AmericanScientific American (April 2006 P16) (April 2006 P16)
The first to demonstrate waferThe first to demonstrate wafer--scale processing of aligned scale processing of aligned nanotube devices and circuitsnanotube devices and circuits
Logic circuits (CMOS inverter NAND NOR)Logic circuits (CMOS inverter NAND NOR)
The first to make transparent nanotube devicesThe first to make transparent nanotube devicesACS Nano in press (2008)ACS Nano in press (2008)
Chip
1
2
3
4
5
Our Achievements on Aligned Single-Walled NanotubesOur Achievements on Aligned SingleOur Achievements on Aligned Single--Walled NanotubesWalled Nanotubes
Synthesis of Aligned Nanotubes on Sapphire QuartzSynthesis of Aligned Nanotubes on Sapphire Quartz
Gas in
Gas out
Sapphire with catalyst
Substrate Sapphire quartzCatalyst FerritinTemperature 900degCGas flow rate
CH4 2000 sccmC2H4 10 sccmH2 800 sccm
Generation IIFull Wafer Production
Generation IIFull Wafer Production
50 μm
2 0
1 5
1 0
5N
umbe
r
2 01 0D iam e te r (nm)500 nm
134 plusmn 030 nm
1 All nanotubes grow normal to the c axis on a-plane sapphire2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin11 All nanotubes grow normal to the c axis on aAll nanotubes grow normal to the c axis on a--plane sapphireplane sapphire2 Narrow diameter distribution of 2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin
c axis
Aligned Nanotubes Grown on a-Plane SapphireAligned Nanotubes Grown on a-Plane Sapphire
Zhou et al JACS 127 5294 (2005)
Zhou Zhou et alet al Nano Letters Nano Letters (2006)(2006)(Top ten hot articles in 2006)
High density SWNTsUp to 40 nanotubes μmInter-nanotube spacing ~ 25 nm
Low density SWNTs
Control of Nanotube DensityControl of Nanotube Density
Zhou et al JACS 127 5294 (2005) Zhou Zhou et alet al Nano Letters (2006) Nano Letters (2006)
a-plane
Red spheres oxygen atomsBlue spheres aluminum atomsPurple plane a-plane orientation
Hypothetic Schematic Diagram of SWNT on a-Plane SapphireHypothetic Schematic Diagram of SWNT on a-Plane Sapphire
Calculation of Lennard-Jones Potential Calculation of Lennard-Jones Potential
sumsum⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
minusminus⎟
⎟
⎠
⎞
⎜⎜
⎝
⎛
minus+
⎥⎥
⎦
⎤
⎢⎢
⎣
⎡
⎟⎟⎠
⎞⎜⎜⎝
⎛
minusminus⎟
⎟⎠
⎞⎜⎜⎝
⎛
minus=
j j
CAl
j
CAlCAl
i i
CO
i
COCO rrrrrrrr
rU
612612
44)( vvvvvvvvv σσ
εσσ
ε
a carbon atom and oxygen atoms in sapphire
a carbon atom and oxygen atoms in sapphire
a carbon atom and Al atoms in sapphire
a carbon atom and Al atoms in sapphire
Interaction between
Interaction between
C-plane C-plane a-plane a-plane
Potential wellPotential wellZhou Zhou et alet al JPCC JPCC 112 15929 (200(20088))
Synthesis of Nanotubes with Controlled Orientations and Positions
Synthesis of Nanotubes with Controlled Orientations and Positions
Catalyst
Photo Resist
QuartzSapphire
Catalyst Island
Aligned NanotubesMetal Electrode
SD
G
Dielectric Layer
3-10 nanotubes microm
Aligned Nanotubes on Quartz Using Patterned CatalystAligned Nanotubes on Quartz Using Patterned Catalystcatalyst
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
(a)
Poly Si Gate
Gate Oxide
SourceDrain Electrode
(b)
NanotubeGate Dielectric
Gate
SourceDrain Electrode
Comparison between Silicon-on-insulator (SOI) and Nanotube-on-Insulator (NOI)
Comparison between SiliconComparison between Silicon--onon--insulator (SOI) and insulator (SOI) and NanotubeNanotube--onon--Insulator (NOI)Insulator (NOI)
SOISOISOI NOINOINOI
Common Features1 Active material (Si or SWNT) is all over the surface2 Many devices can be patterned anywhere on the substrate3 Unwanted silicon or SWNTs can be removed via etching4 SOI and NOI offer minimized parasitic capacitance faster switching speed
and lower dynamic power consumption
Common FeaturesCommon Features11 Active material (Si or SWNT) is all over the surfaceActive material (Si or SWNT) is all over the surface22 Many devices can be patterned anywhere on the substrateMany devices can be patterned anywhere on the substrate33 Unwanted silicon or Unwanted silicon or SWNTsSWNTs can be removed via etchingcan be removed via etching44 SOI and NOI offer minimized parasitic capacitance faster switchSOI and NOI offer minimized parasitic capacitance faster switching speed ing speed
and lower dynamic power consumptionand lower dynamic power consumption Zhou et al Nano Letters (2006)
a-Sapphire
Wafer-Scale Aligned Nanotube SynthesisWafer-Scale Aligned Nanotube Synthesis
1200
1000
800
600
400
200
Tem
pera
ture
200150100500
Time (min)
Growth Annealing
Key meticulous temperature control amp uniform growth
1μm
Quartz 1000
800
600
400
200Tem
pera
ture
6004002000
Time (min)
Growth Annealing
1μm
4 inch substrate
Gas in
Gas out
Quartz or Sapphire with patterned
catalyst
9 feet-long growth furnace with three-zone
Wafer-Scale CNT TransferWafer-Scale CNT TransferTransfer fullTransfer full--wafer of wafer of CNTsCNTs from quartz growth substrate to SiOfrom quartz growth substrate to SiO22Si fabrication Si fabrication
substrate substrate allows largeallows large--scale integrationscale integration
Nano Lett 9 189ndash197 20094
Wafer-Scale Aligned Nanotube Device FabricationWafer-Scale Aligned Nanotube Device Fabrication
Back-Gated Submicron TransistorsBack-Gated Submicron Transistors
Back-gated transistors
1 microm
L = 1 microm
1 microm
L = 075 microm
1 microm
L = 05 microm
I-Vg curves Channel length dependence
-120
-100
-80
-60
-40
-20
0
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
-60
-40
-20
0
I ds (μ
Α)
-1500Vds (V)
-1 V
-08 V
-06 V
-04 V
-02 V
Vg from -8V to 8V
15
10
05
I ds (m
A)
-10 -5 0 5 10Vg (V)
L = 05 microm L = 075 microm L = 1 microm L = 2 microm L = 5 microm L = 10 microm L = 20 microm
80
60
40
20
gm
(μ S
)
5 6 7 81
2 3 4 5 6 7 810
2
L(μm)
2
4
6810-6
2
4
6810-5
I DW
(mA
microm
) gm
Ion Ioff
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
CNT is a tubular form of carbon with diameter as small as 1 nm Length few nm to cm
CNT is configurationally equivalent to a two dimensional graphenesheet rolled into a tube
CNT exhibits1 Carrier mobility ~ 100000 cm2Vs2 Youngrsquos modulus over 1 Tera
Pascal as stiff as diamond3 Tensile strength ~ 200 GPa
Zigzag
Armchair
Chiral
MOLECULAR STRUCTUREMOLECULAR STRUCTURE
CNT can be metallic or semiconducting depending on chirality
Benchmarking CNT FETsBenchmarking CNT FETs
1
10
100
1000
10000
100000
130 90 65 45 22
Technology Node (nm)
Nor
mal
ized
FO
A
26X25X
28X 27X
Intrinsic CNT
MOS CNT FET
Band-edge SB CNTMidgap SB CNT
5000X
60X
50X20X
Si MOSFET
Source Ali Keshavarzi Intel
Nanotube Transistor ResearchNanotube Transistor ResearchGate
8nm HfO2
SiO2
p++ Si
PdPd CNT
Javey et al Nano Letters 4 1319 2004Delft Tans et al Nature 393 49 1998
Many people have studied individual nanotube transistors however the challenge is to integrate nanotube devices
Many people have studied individual nanotube transistors however the challenge is to integrate nanotube devices
Appenzeller et al PRL 93 19 2005
Drain
SourceGate
DrainSourceGate
Sapphire Substrate
GateOxide
Liu et al Nano Letters 6 34 2006
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Traditional approach On-Site Synthesis of Single-Walled Carbon Nanotubes
Traditional approach On-Site Synthesis of Single-Walled Carbon Nanotubes
SiSiO2
PMMA
Catalyst
CH4nanotube
Catalyst island
900 ordmC900 ordmC
metal electrode
H Dai et al Nature 395 878 (1998)
Infrastructure Nanotube CVD Generation IInfrastructure Nanotube CVD Generation I
1 μm
1 μm
26 nm in diameter
10 nm in diameter
High-quality nanotubes can be grown at specific positions
-60
-50
-40
-30
-20
-10
0
I DS(
nA)
-10-08-06-04-0200VDS(V)
Vg -4 V
0 V
2 V
6 V
Nanotube transistor can be easily produced
Si back gate
SiO2
S D
Integrated Nanotube SystemsComplementary Carbon Nanotube Inverter
Integrated Nanotube SystemsComplementary Carbon Nanotube Inverter
Carbon Nanotube Field-Effect Inverters X Liu R Lee J Han C Zhou Appl Phys Lett 79 3329 (2001)
One of the first integrated systems made of carbon nanotubes
Si back gate
K
Vin
Vout
VDD GND
p-type CNT n-type CNT
60
40
20
0
I DS(
nA)
-4 -2 0 2 4Vg(V)
VDS=10 mV
P type MOSFET12
8
4
0
I DS (
nA)
-4 -2 0 2 4Vg (V)
VDS=10 mV
N type MOSFET25
20
15
10
05
00
Vou
t(V)
252015100500Vin(V)
VDD=29 V
Vin Vout
0 V
VDD
p
n
Integrated Nanotube SystemsRing Oscillators Demonstrated by Avouris et al
Integrated Nanotube SystemsRing Oscillators Demonstrated by Avouris et al
Ph Avouris et al Science 311 1735 (2006)
Is there a way to assemble large quantities of nanotube devices
State-of-the-art of nanotube integration
Aligned Nanotubes for Devices and Circuits Aligned Nanotubes for Devices and Circuits
-- Project Mission Project Mission We want to tackle the challenging issue of We want to tackle the challenging issue of nanotube nanotube assembly and integrationassembly and integration
We want to grow carbon nanotubes withWe want to grow carbon nanotubes withControlled orientation (achieved by using Controlled orientation (achieved by using sapphire and quartz) sapphire and quartz) Controlled position (achieved) Controlled position (achieved) Controlled density (achieved) Controlled density (achieved) Controlled diameter (ongoing)Controlled diameter (ongoing)Controlled Controlled chiralitychirality (ongoing)(ongoing)
-- Our Approach Our Approach A novel nanotubeA novel nanotube--onon--insulator (NOI) insulator (NOI) approach based on approach based on aligned nanotubesaligned nanotubes for for integrated nanotube circuitsintegrated nanotube circuits Nanotube
devicesNanotube
circuits
Quartz SubstrateCatalyst Particle
Quartz Substrate
Nanotube
One of the first to grow aligned nanotubes on sapphireOne of the first to grow aligned nanotubes on sapphireJ of Am Chem Soc 127 5294 J of Am Chem Soc 127 5294 -- 5295 (2005) 5295 (2005)
The first to make aligned nanotube transistorsThe first to make aligned nanotube transistorsNano Letters 6 34Nano Letters 6 34--39 (2006)39 (2006)Reported by Reported by Scientific AmericanScientific American (April 2006 P16) (April 2006 P16)
The first to demonstrate waferThe first to demonstrate wafer--scale processing of aligned scale processing of aligned nanotube devices and circuitsnanotube devices and circuits
Logic circuits (CMOS inverter NAND NOR)Logic circuits (CMOS inverter NAND NOR)
The first to make transparent nanotube devicesThe first to make transparent nanotube devicesACS Nano in press (2008)ACS Nano in press (2008)
Chip
1
2
3
4
5
Our Achievements on Aligned Single-Walled NanotubesOur Achievements on Aligned SingleOur Achievements on Aligned Single--Walled NanotubesWalled Nanotubes
Synthesis of Aligned Nanotubes on Sapphire QuartzSynthesis of Aligned Nanotubes on Sapphire Quartz
Gas in
Gas out
Sapphire with catalyst
Substrate Sapphire quartzCatalyst FerritinTemperature 900degCGas flow rate
CH4 2000 sccmC2H4 10 sccmH2 800 sccm
Generation IIFull Wafer Production
Generation IIFull Wafer Production
50 μm
2 0
1 5
1 0
5N
umbe
r
2 01 0D iam e te r (nm)500 nm
134 plusmn 030 nm
1 All nanotubes grow normal to the c axis on a-plane sapphire2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin11 All nanotubes grow normal to the c axis on aAll nanotubes grow normal to the c axis on a--plane sapphireplane sapphire2 Narrow diameter distribution of 2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin
c axis
Aligned Nanotubes Grown on a-Plane SapphireAligned Nanotubes Grown on a-Plane Sapphire
Zhou et al JACS 127 5294 (2005)
Zhou Zhou et alet al Nano Letters Nano Letters (2006)(2006)(Top ten hot articles in 2006)
High density SWNTsUp to 40 nanotubes μmInter-nanotube spacing ~ 25 nm
Low density SWNTs
Control of Nanotube DensityControl of Nanotube Density
Zhou et al JACS 127 5294 (2005) Zhou Zhou et alet al Nano Letters (2006) Nano Letters (2006)
a-plane
Red spheres oxygen atomsBlue spheres aluminum atomsPurple plane a-plane orientation
Hypothetic Schematic Diagram of SWNT on a-Plane SapphireHypothetic Schematic Diagram of SWNT on a-Plane Sapphire
Calculation of Lennard-Jones Potential Calculation of Lennard-Jones Potential
sumsum⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
minusminus⎟
⎟
⎠
⎞
⎜⎜
⎝
⎛
minus+
⎥⎥
⎦
⎤
⎢⎢
⎣
⎡
⎟⎟⎠
⎞⎜⎜⎝
⎛
minusminus⎟
⎟⎠
⎞⎜⎜⎝
⎛
minus=
j j
CAl
j
CAlCAl
i i
CO
i
COCO rrrrrrrr
rU
612612
44)( vvvvvvvvv σσ
εσσ
ε
a carbon atom and oxygen atoms in sapphire
a carbon atom and oxygen atoms in sapphire
a carbon atom and Al atoms in sapphire
a carbon atom and Al atoms in sapphire
Interaction between
Interaction between
C-plane C-plane a-plane a-plane
Potential wellPotential wellZhou Zhou et alet al JPCC JPCC 112 15929 (200(20088))
Synthesis of Nanotubes with Controlled Orientations and Positions
Synthesis of Nanotubes with Controlled Orientations and Positions
Catalyst
Photo Resist
QuartzSapphire
Catalyst Island
Aligned NanotubesMetal Electrode
SD
G
Dielectric Layer
3-10 nanotubes microm
Aligned Nanotubes on Quartz Using Patterned CatalystAligned Nanotubes on Quartz Using Patterned Catalystcatalyst
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
(a)
Poly Si Gate
Gate Oxide
SourceDrain Electrode
(b)
NanotubeGate Dielectric
Gate
SourceDrain Electrode
Comparison between Silicon-on-insulator (SOI) and Nanotube-on-Insulator (NOI)
Comparison between SiliconComparison between Silicon--onon--insulator (SOI) and insulator (SOI) and NanotubeNanotube--onon--Insulator (NOI)Insulator (NOI)
SOISOISOI NOINOINOI
Common Features1 Active material (Si or SWNT) is all over the surface2 Many devices can be patterned anywhere on the substrate3 Unwanted silicon or SWNTs can be removed via etching4 SOI and NOI offer minimized parasitic capacitance faster switching speed
and lower dynamic power consumption
Common FeaturesCommon Features11 Active material (Si or SWNT) is all over the surfaceActive material (Si or SWNT) is all over the surface22 Many devices can be patterned anywhere on the substrateMany devices can be patterned anywhere on the substrate33 Unwanted silicon or Unwanted silicon or SWNTsSWNTs can be removed via etchingcan be removed via etching44 SOI and NOI offer minimized parasitic capacitance faster switchSOI and NOI offer minimized parasitic capacitance faster switching speed ing speed
and lower dynamic power consumptionand lower dynamic power consumption Zhou et al Nano Letters (2006)
a-Sapphire
Wafer-Scale Aligned Nanotube SynthesisWafer-Scale Aligned Nanotube Synthesis
1200
1000
800
600
400
200
Tem
pera
ture
200150100500
Time (min)
Growth Annealing
Key meticulous temperature control amp uniform growth
1μm
Quartz 1000
800
600
400
200Tem
pera
ture
6004002000
Time (min)
Growth Annealing
1μm
4 inch substrate
Gas in
Gas out
Quartz or Sapphire with patterned
catalyst
9 feet-long growth furnace with three-zone
Wafer-Scale CNT TransferWafer-Scale CNT TransferTransfer fullTransfer full--wafer of wafer of CNTsCNTs from quartz growth substrate to SiOfrom quartz growth substrate to SiO22Si fabrication Si fabrication
substrate substrate allows largeallows large--scale integrationscale integration
Nano Lett 9 189ndash197 20094
Wafer-Scale Aligned Nanotube Device FabricationWafer-Scale Aligned Nanotube Device Fabrication
Back-Gated Submicron TransistorsBack-Gated Submicron Transistors
Back-gated transistors
1 microm
L = 1 microm
1 microm
L = 075 microm
1 microm
L = 05 microm
I-Vg curves Channel length dependence
-120
-100
-80
-60
-40
-20
0
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
-60
-40
-20
0
I ds (μ
Α)
-1500Vds (V)
-1 V
-08 V
-06 V
-04 V
-02 V
Vg from -8V to 8V
15
10
05
I ds (m
A)
-10 -5 0 5 10Vg (V)
L = 05 microm L = 075 microm L = 1 microm L = 2 microm L = 5 microm L = 10 microm L = 20 microm
80
60
40
20
gm
(μ S
)
5 6 7 81
2 3 4 5 6 7 810
2
L(μm)
2
4
6810-6
2
4
6810-5
I DW
(mA
microm
) gm
Ion Ioff
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Zigzag
Armchair
Chiral
MOLECULAR STRUCTUREMOLECULAR STRUCTURE
CNT can be metallic or semiconducting depending on chirality
Benchmarking CNT FETsBenchmarking CNT FETs
1
10
100
1000
10000
100000
130 90 65 45 22
Technology Node (nm)
Nor
mal
ized
FO
A
26X25X
28X 27X
Intrinsic CNT
MOS CNT FET
Band-edge SB CNTMidgap SB CNT
5000X
60X
50X20X
Si MOSFET
Source Ali Keshavarzi Intel
Nanotube Transistor ResearchNanotube Transistor ResearchGate
8nm HfO2
SiO2
p++ Si
PdPd CNT
Javey et al Nano Letters 4 1319 2004Delft Tans et al Nature 393 49 1998
Many people have studied individual nanotube transistors however the challenge is to integrate nanotube devices
Many people have studied individual nanotube transistors however the challenge is to integrate nanotube devices
Appenzeller et al PRL 93 19 2005
Drain
SourceGate
DrainSourceGate
Sapphire Substrate
GateOxide
Liu et al Nano Letters 6 34 2006
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Traditional approach On-Site Synthesis of Single-Walled Carbon Nanotubes
Traditional approach On-Site Synthesis of Single-Walled Carbon Nanotubes
SiSiO2
PMMA
Catalyst
CH4nanotube
Catalyst island
900 ordmC900 ordmC
metal electrode
H Dai et al Nature 395 878 (1998)
Infrastructure Nanotube CVD Generation IInfrastructure Nanotube CVD Generation I
1 μm
1 μm
26 nm in diameter
10 nm in diameter
High-quality nanotubes can be grown at specific positions
-60
-50
-40
-30
-20
-10
0
I DS(
nA)
-10-08-06-04-0200VDS(V)
Vg -4 V
0 V
2 V
6 V
Nanotube transistor can be easily produced
Si back gate
SiO2
S D
Integrated Nanotube SystemsComplementary Carbon Nanotube Inverter
Integrated Nanotube SystemsComplementary Carbon Nanotube Inverter
Carbon Nanotube Field-Effect Inverters X Liu R Lee J Han C Zhou Appl Phys Lett 79 3329 (2001)
One of the first integrated systems made of carbon nanotubes
Si back gate
K
Vin
Vout
VDD GND
p-type CNT n-type CNT
60
40
20
0
I DS(
nA)
-4 -2 0 2 4Vg(V)
VDS=10 mV
P type MOSFET12
8
4
0
I DS (
nA)
-4 -2 0 2 4Vg (V)
VDS=10 mV
N type MOSFET25
20
15
10
05
00
Vou
t(V)
252015100500Vin(V)
VDD=29 V
Vin Vout
0 V
VDD
p
n
Integrated Nanotube SystemsRing Oscillators Demonstrated by Avouris et al
Integrated Nanotube SystemsRing Oscillators Demonstrated by Avouris et al
Ph Avouris et al Science 311 1735 (2006)
Is there a way to assemble large quantities of nanotube devices
State-of-the-art of nanotube integration
Aligned Nanotubes for Devices and Circuits Aligned Nanotubes for Devices and Circuits
-- Project Mission Project Mission We want to tackle the challenging issue of We want to tackle the challenging issue of nanotube nanotube assembly and integrationassembly and integration
We want to grow carbon nanotubes withWe want to grow carbon nanotubes withControlled orientation (achieved by using Controlled orientation (achieved by using sapphire and quartz) sapphire and quartz) Controlled position (achieved) Controlled position (achieved) Controlled density (achieved) Controlled density (achieved) Controlled diameter (ongoing)Controlled diameter (ongoing)Controlled Controlled chiralitychirality (ongoing)(ongoing)
-- Our Approach Our Approach A novel nanotubeA novel nanotube--onon--insulator (NOI) insulator (NOI) approach based on approach based on aligned nanotubesaligned nanotubes for for integrated nanotube circuitsintegrated nanotube circuits Nanotube
devicesNanotube
circuits
Quartz SubstrateCatalyst Particle
Quartz Substrate
Nanotube
One of the first to grow aligned nanotubes on sapphireOne of the first to grow aligned nanotubes on sapphireJ of Am Chem Soc 127 5294 J of Am Chem Soc 127 5294 -- 5295 (2005) 5295 (2005)
The first to make aligned nanotube transistorsThe first to make aligned nanotube transistorsNano Letters 6 34Nano Letters 6 34--39 (2006)39 (2006)Reported by Reported by Scientific AmericanScientific American (April 2006 P16) (April 2006 P16)
The first to demonstrate waferThe first to demonstrate wafer--scale processing of aligned scale processing of aligned nanotube devices and circuitsnanotube devices and circuits
Logic circuits (CMOS inverter NAND NOR)Logic circuits (CMOS inverter NAND NOR)
The first to make transparent nanotube devicesThe first to make transparent nanotube devicesACS Nano in press (2008)ACS Nano in press (2008)
Chip
1
2
3
4
5
Our Achievements on Aligned Single-Walled NanotubesOur Achievements on Aligned SingleOur Achievements on Aligned Single--Walled NanotubesWalled Nanotubes
Synthesis of Aligned Nanotubes on Sapphire QuartzSynthesis of Aligned Nanotubes on Sapphire Quartz
Gas in
Gas out
Sapphire with catalyst
Substrate Sapphire quartzCatalyst FerritinTemperature 900degCGas flow rate
CH4 2000 sccmC2H4 10 sccmH2 800 sccm
Generation IIFull Wafer Production
Generation IIFull Wafer Production
50 μm
2 0
1 5
1 0
5N
umbe
r
2 01 0D iam e te r (nm)500 nm
134 plusmn 030 nm
1 All nanotubes grow normal to the c axis on a-plane sapphire2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin11 All nanotubes grow normal to the c axis on aAll nanotubes grow normal to the c axis on a--plane sapphireplane sapphire2 Narrow diameter distribution of 2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin
c axis
Aligned Nanotubes Grown on a-Plane SapphireAligned Nanotubes Grown on a-Plane Sapphire
Zhou et al JACS 127 5294 (2005)
Zhou Zhou et alet al Nano Letters Nano Letters (2006)(2006)(Top ten hot articles in 2006)
High density SWNTsUp to 40 nanotubes μmInter-nanotube spacing ~ 25 nm
Low density SWNTs
Control of Nanotube DensityControl of Nanotube Density
Zhou et al JACS 127 5294 (2005) Zhou Zhou et alet al Nano Letters (2006) Nano Letters (2006)
a-plane
Red spheres oxygen atomsBlue spheres aluminum atomsPurple plane a-plane orientation
Hypothetic Schematic Diagram of SWNT on a-Plane SapphireHypothetic Schematic Diagram of SWNT on a-Plane Sapphire
Calculation of Lennard-Jones Potential Calculation of Lennard-Jones Potential
sumsum⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
minusminus⎟
⎟
⎠
⎞
⎜⎜
⎝
⎛
minus+
⎥⎥
⎦
⎤
⎢⎢
⎣
⎡
⎟⎟⎠
⎞⎜⎜⎝
⎛
minusminus⎟
⎟⎠
⎞⎜⎜⎝
⎛
minus=
j j
CAl
j
CAlCAl
i i
CO
i
COCO rrrrrrrr
rU
612612
44)( vvvvvvvvv σσ
εσσ
ε
a carbon atom and oxygen atoms in sapphire
a carbon atom and oxygen atoms in sapphire
a carbon atom and Al atoms in sapphire
a carbon atom and Al atoms in sapphire
Interaction between
Interaction between
C-plane C-plane a-plane a-plane
Potential wellPotential wellZhou Zhou et alet al JPCC JPCC 112 15929 (200(20088))
Synthesis of Nanotubes with Controlled Orientations and Positions
Synthesis of Nanotubes with Controlled Orientations and Positions
Catalyst
Photo Resist
QuartzSapphire
Catalyst Island
Aligned NanotubesMetal Electrode
SD
G
Dielectric Layer
3-10 nanotubes microm
Aligned Nanotubes on Quartz Using Patterned CatalystAligned Nanotubes on Quartz Using Patterned Catalystcatalyst
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
(a)
Poly Si Gate
Gate Oxide
SourceDrain Electrode
(b)
NanotubeGate Dielectric
Gate
SourceDrain Electrode
Comparison between Silicon-on-insulator (SOI) and Nanotube-on-Insulator (NOI)
Comparison between SiliconComparison between Silicon--onon--insulator (SOI) and insulator (SOI) and NanotubeNanotube--onon--Insulator (NOI)Insulator (NOI)
SOISOISOI NOINOINOI
Common Features1 Active material (Si or SWNT) is all over the surface2 Many devices can be patterned anywhere on the substrate3 Unwanted silicon or SWNTs can be removed via etching4 SOI and NOI offer minimized parasitic capacitance faster switching speed
and lower dynamic power consumption
Common FeaturesCommon Features11 Active material (Si or SWNT) is all over the surfaceActive material (Si or SWNT) is all over the surface22 Many devices can be patterned anywhere on the substrateMany devices can be patterned anywhere on the substrate33 Unwanted silicon or Unwanted silicon or SWNTsSWNTs can be removed via etchingcan be removed via etching44 SOI and NOI offer minimized parasitic capacitance faster switchSOI and NOI offer minimized parasitic capacitance faster switching speed ing speed
and lower dynamic power consumptionand lower dynamic power consumption Zhou et al Nano Letters (2006)
a-Sapphire
Wafer-Scale Aligned Nanotube SynthesisWafer-Scale Aligned Nanotube Synthesis
1200
1000
800
600
400
200
Tem
pera
ture
200150100500
Time (min)
Growth Annealing
Key meticulous temperature control amp uniform growth
1μm
Quartz 1000
800
600
400
200Tem
pera
ture
6004002000
Time (min)
Growth Annealing
1μm
4 inch substrate
Gas in
Gas out
Quartz or Sapphire with patterned
catalyst
9 feet-long growth furnace with three-zone
Wafer-Scale CNT TransferWafer-Scale CNT TransferTransfer fullTransfer full--wafer of wafer of CNTsCNTs from quartz growth substrate to SiOfrom quartz growth substrate to SiO22Si fabrication Si fabrication
substrate substrate allows largeallows large--scale integrationscale integration
Nano Lett 9 189ndash197 20094
Wafer-Scale Aligned Nanotube Device FabricationWafer-Scale Aligned Nanotube Device Fabrication
Back-Gated Submicron TransistorsBack-Gated Submicron Transistors
Back-gated transistors
1 microm
L = 1 microm
1 microm
L = 075 microm
1 microm
L = 05 microm
I-Vg curves Channel length dependence
-120
-100
-80
-60
-40
-20
0
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
-60
-40
-20
0
I ds (μ
Α)
-1500Vds (V)
-1 V
-08 V
-06 V
-04 V
-02 V
Vg from -8V to 8V
15
10
05
I ds (m
A)
-10 -5 0 5 10Vg (V)
L = 05 microm L = 075 microm L = 1 microm L = 2 microm L = 5 microm L = 10 microm L = 20 microm
80
60
40
20
gm
(μ S
)
5 6 7 81
2 3 4 5 6 7 810
2
L(μm)
2
4
6810-6
2
4
6810-5
I DW
(mA
microm
) gm
Ion Ioff
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Benchmarking CNT FETsBenchmarking CNT FETs
1
10
100
1000
10000
100000
130 90 65 45 22
Technology Node (nm)
Nor
mal
ized
FO
A
26X25X
28X 27X
Intrinsic CNT
MOS CNT FET
Band-edge SB CNTMidgap SB CNT
5000X
60X
50X20X
Si MOSFET
Source Ali Keshavarzi Intel
Nanotube Transistor ResearchNanotube Transistor ResearchGate
8nm HfO2
SiO2
p++ Si
PdPd CNT
Javey et al Nano Letters 4 1319 2004Delft Tans et al Nature 393 49 1998
Many people have studied individual nanotube transistors however the challenge is to integrate nanotube devices
Many people have studied individual nanotube transistors however the challenge is to integrate nanotube devices
Appenzeller et al PRL 93 19 2005
Drain
SourceGate
DrainSourceGate
Sapphire Substrate
GateOxide
Liu et al Nano Letters 6 34 2006
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Traditional approach On-Site Synthesis of Single-Walled Carbon Nanotubes
Traditional approach On-Site Synthesis of Single-Walled Carbon Nanotubes
SiSiO2
PMMA
Catalyst
CH4nanotube
Catalyst island
900 ordmC900 ordmC
metal electrode
H Dai et al Nature 395 878 (1998)
Infrastructure Nanotube CVD Generation IInfrastructure Nanotube CVD Generation I
1 μm
1 μm
26 nm in diameter
10 nm in diameter
High-quality nanotubes can be grown at specific positions
-60
-50
-40
-30
-20
-10
0
I DS(
nA)
-10-08-06-04-0200VDS(V)
Vg -4 V
0 V
2 V
6 V
Nanotube transistor can be easily produced
Si back gate
SiO2
S D
Integrated Nanotube SystemsComplementary Carbon Nanotube Inverter
Integrated Nanotube SystemsComplementary Carbon Nanotube Inverter
Carbon Nanotube Field-Effect Inverters X Liu R Lee J Han C Zhou Appl Phys Lett 79 3329 (2001)
One of the first integrated systems made of carbon nanotubes
Si back gate
K
Vin
Vout
VDD GND
p-type CNT n-type CNT
60
40
20
0
I DS(
nA)
-4 -2 0 2 4Vg(V)
VDS=10 mV
P type MOSFET12
8
4
0
I DS (
nA)
-4 -2 0 2 4Vg (V)
VDS=10 mV
N type MOSFET25
20
15
10
05
00
Vou
t(V)
252015100500Vin(V)
VDD=29 V
Vin Vout
0 V
VDD
p
n
Integrated Nanotube SystemsRing Oscillators Demonstrated by Avouris et al
Integrated Nanotube SystemsRing Oscillators Demonstrated by Avouris et al
Ph Avouris et al Science 311 1735 (2006)
Is there a way to assemble large quantities of nanotube devices
State-of-the-art of nanotube integration
Aligned Nanotubes for Devices and Circuits Aligned Nanotubes for Devices and Circuits
-- Project Mission Project Mission We want to tackle the challenging issue of We want to tackle the challenging issue of nanotube nanotube assembly and integrationassembly and integration
We want to grow carbon nanotubes withWe want to grow carbon nanotubes withControlled orientation (achieved by using Controlled orientation (achieved by using sapphire and quartz) sapphire and quartz) Controlled position (achieved) Controlled position (achieved) Controlled density (achieved) Controlled density (achieved) Controlled diameter (ongoing)Controlled diameter (ongoing)Controlled Controlled chiralitychirality (ongoing)(ongoing)
-- Our Approach Our Approach A novel nanotubeA novel nanotube--onon--insulator (NOI) insulator (NOI) approach based on approach based on aligned nanotubesaligned nanotubes for for integrated nanotube circuitsintegrated nanotube circuits Nanotube
devicesNanotube
circuits
Quartz SubstrateCatalyst Particle
Quartz Substrate
Nanotube
One of the first to grow aligned nanotubes on sapphireOne of the first to grow aligned nanotubes on sapphireJ of Am Chem Soc 127 5294 J of Am Chem Soc 127 5294 -- 5295 (2005) 5295 (2005)
The first to make aligned nanotube transistorsThe first to make aligned nanotube transistorsNano Letters 6 34Nano Letters 6 34--39 (2006)39 (2006)Reported by Reported by Scientific AmericanScientific American (April 2006 P16) (April 2006 P16)
The first to demonstrate waferThe first to demonstrate wafer--scale processing of aligned scale processing of aligned nanotube devices and circuitsnanotube devices and circuits
Logic circuits (CMOS inverter NAND NOR)Logic circuits (CMOS inverter NAND NOR)
The first to make transparent nanotube devicesThe first to make transparent nanotube devicesACS Nano in press (2008)ACS Nano in press (2008)
Chip
1
2
3
4
5
Our Achievements on Aligned Single-Walled NanotubesOur Achievements on Aligned SingleOur Achievements on Aligned Single--Walled NanotubesWalled Nanotubes
Synthesis of Aligned Nanotubes on Sapphire QuartzSynthesis of Aligned Nanotubes on Sapphire Quartz
Gas in
Gas out
Sapphire with catalyst
Substrate Sapphire quartzCatalyst FerritinTemperature 900degCGas flow rate
CH4 2000 sccmC2H4 10 sccmH2 800 sccm
Generation IIFull Wafer Production
Generation IIFull Wafer Production
50 μm
2 0
1 5
1 0
5N
umbe
r
2 01 0D iam e te r (nm)500 nm
134 plusmn 030 nm
1 All nanotubes grow normal to the c axis on a-plane sapphire2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin11 All nanotubes grow normal to the c axis on aAll nanotubes grow normal to the c axis on a--plane sapphireplane sapphire2 Narrow diameter distribution of 2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin
c axis
Aligned Nanotubes Grown on a-Plane SapphireAligned Nanotubes Grown on a-Plane Sapphire
Zhou et al JACS 127 5294 (2005)
Zhou Zhou et alet al Nano Letters Nano Letters (2006)(2006)(Top ten hot articles in 2006)
High density SWNTsUp to 40 nanotubes μmInter-nanotube spacing ~ 25 nm
Low density SWNTs
Control of Nanotube DensityControl of Nanotube Density
Zhou et al JACS 127 5294 (2005) Zhou Zhou et alet al Nano Letters (2006) Nano Letters (2006)
a-plane
Red spheres oxygen atomsBlue spheres aluminum atomsPurple plane a-plane orientation
Hypothetic Schematic Diagram of SWNT on a-Plane SapphireHypothetic Schematic Diagram of SWNT on a-Plane Sapphire
Calculation of Lennard-Jones Potential Calculation of Lennard-Jones Potential
sumsum⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
minusminus⎟
⎟
⎠
⎞
⎜⎜
⎝
⎛
minus+
⎥⎥
⎦
⎤
⎢⎢
⎣
⎡
⎟⎟⎠
⎞⎜⎜⎝
⎛
minusminus⎟
⎟⎠
⎞⎜⎜⎝
⎛
minus=
j j
CAl
j
CAlCAl
i i
CO
i
COCO rrrrrrrr
rU
612612
44)( vvvvvvvvv σσ
εσσ
ε
a carbon atom and oxygen atoms in sapphire
a carbon atom and oxygen atoms in sapphire
a carbon atom and Al atoms in sapphire
a carbon atom and Al atoms in sapphire
Interaction between
Interaction between
C-plane C-plane a-plane a-plane
Potential wellPotential wellZhou Zhou et alet al JPCC JPCC 112 15929 (200(20088))
Synthesis of Nanotubes with Controlled Orientations and Positions
Synthesis of Nanotubes with Controlled Orientations and Positions
Catalyst
Photo Resist
QuartzSapphire
Catalyst Island
Aligned NanotubesMetal Electrode
SD
G
Dielectric Layer
3-10 nanotubes microm
Aligned Nanotubes on Quartz Using Patterned CatalystAligned Nanotubes on Quartz Using Patterned Catalystcatalyst
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
(a)
Poly Si Gate
Gate Oxide
SourceDrain Electrode
(b)
NanotubeGate Dielectric
Gate
SourceDrain Electrode
Comparison between Silicon-on-insulator (SOI) and Nanotube-on-Insulator (NOI)
Comparison between SiliconComparison between Silicon--onon--insulator (SOI) and insulator (SOI) and NanotubeNanotube--onon--Insulator (NOI)Insulator (NOI)
SOISOISOI NOINOINOI
Common Features1 Active material (Si or SWNT) is all over the surface2 Many devices can be patterned anywhere on the substrate3 Unwanted silicon or SWNTs can be removed via etching4 SOI and NOI offer minimized parasitic capacitance faster switching speed
and lower dynamic power consumption
Common FeaturesCommon Features11 Active material (Si or SWNT) is all over the surfaceActive material (Si or SWNT) is all over the surface22 Many devices can be patterned anywhere on the substrateMany devices can be patterned anywhere on the substrate33 Unwanted silicon or Unwanted silicon or SWNTsSWNTs can be removed via etchingcan be removed via etching44 SOI and NOI offer minimized parasitic capacitance faster switchSOI and NOI offer minimized parasitic capacitance faster switching speed ing speed
and lower dynamic power consumptionand lower dynamic power consumption Zhou et al Nano Letters (2006)
a-Sapphire
Wafer-Scale Aligned Nanotube SynthesisWafer-Scale Aligned Nanotube Synthesis
1200
1000
800
600
400
200
Tem
pera
ture
200150100500
Time (min)
Growth Annealing
Key meticulous temperature control amp uniform growth
1μm
Quartz 1000
800
600
400
200Tem
pera
ture
6004002000
Time (min)
Growth Annealing
1μm
4 inch substrate
Gas in
Gas out
Quartz or Sapphire with patterned
catalyst
9 feet-long growth furnace with three-zone
Wafer-Scale CNT TransferWafer-Scale CNT TransferTransfer fullTransfer full--wafer of wafer of CNTsCNTs from quartz growth substrate to SiOfrom quartz growth substrate to SiO22Si fabrication Si fabrication
substrate substrate allows largeallows large--scale integrationscale integration
Nano Lett 9 189ndash197 20094
Wafer-Scale Aligned Nanotube Device FabricationWafer-Scale Aligned Nanotube Device Fabrication
Back-Gated Submicron TransistorsBack-Gated Submicron Transistors
Back-gated transistors
1 microm
L = 1 microm
1 microm
L = 075 microm
1 microm
L = 05 microm
I-Vg curves Channel length dependence
-120
-100
-80
-60
-40
-20
0
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
-60
-40
-20
0
I ds (μ
Α)
-1500Vds (V)
-1 V
-08 V
-06 V
-04 V
-02 V
Vg from -8V to 8V
15
10
05
I ds (m
A)
-10 -5 0 5 10Vg (V)
L = 05 microm L = 075 microm L = 1 microm L = 2 microm L = 5 microm L = 10 microm L = 20 microm
80
60
40
20
gm
(μ S
)
5 6 7 81
2 3 4 5 6 7 810
2
L(μm)
2
4
6810-6
2
4
6810-5
I DW
(mA
microm
) gm
Ion Ioff
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Nanotube Transistor ResearchNanotube Transistor ResearchGate
8nm HfO2
SiO2
p++ Si
PdPd CNT
Javey et al Nano Letters 4 1319 2004Delft Tans et al Nature 393 49 1998
Many people have studied individual nanotube transistors however the challenge is to integrate nanotube devices
Many people have studied individual nanotube transistors however the challenge is to integrate nanotube devices
Appenzeller et al PRL 93 19 2005
Drain
SourceGate
DrainSourceGate
Sapphire Substrate
GateOxide
Liu et al Nano Letters 6 34 2006
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Traditional approach On-Site Synthesis of Single-Walled Carbon Nanotubes
Traditional approach On-Site Synthesis of Single-Walled Carbon Nanotubes
SiSiO2
PMMA
Catalyst
CH4nanotube
Catalyst island
900 ordmC900 ordmC
metal electrode
H Dai et al Nature 395 878 (1998)
Infrastructure Nanotube CVD Generation IInfrastructure Nanotube CVD Generation I
1 μm
1 μm
26 nm in diameter
10 nm in diameter
High-quality nanotubes can be grown at specific positions
-60
-50
-40
-30
-20
-10
0
I DS(
nA)
-10-08-06-04-0200VDS(V)
Vg -4 V
0 V
2 V
6 V
Nanotube transistor can be easily produced
Si back gate
SiO2
S D
Integrated Nanotube SystemsComplementary Carbon Nanotube Inverter
Integrated Nanotube SystemsComplementary Carbon Nanotube Inverter
Carbon Nanotube Field-Effect Inverters X Liu R Lee J Han C Zhou Appl Phys Lett 79 3329 (2001)
One of the first integrated systems made of carbon nanotubes
Si back gate
K
Vin
Vout
VDD GND
p-type CNT n-type CNT
60
40
20
0
I DS(
nA)
-4 -2 0 2 4Vg(V)
VDS=10 mV
P type MOSFET12
8
4
0
I DS (
nA)
-4 -2 0 2 4Vg (V)
VDS=10 mV
N type MOSFET25
20
15
10
05
00
Vou
t(V)
252015100500Vin(V)
VDD=29 V
Vin Vout
0 V
VDD
p
n
Integrated Nanotube SystemsRing Oscillators Demonstrated by Avouris et al
Integrated Nanotube SystemsRing Oscillators Demonstrated by Avouris et al
Ph Avouris et al Science 311 1735 (2006)
Is there a way to assemble large quantities of nanotube devices
State-of-the-art of nanotube integration
Aligned Nanotubes for Devices and Circuits Aligned Nanotubes for Devices and Circuits
-- Project Mission Project Mission We want to tackle the challenging issue of We want to tackle the challenging issue of nanotube nanotube assembly and integrationassembly and integration
We want to grow carbon nanotubes withWe want to grow carbon nanotubes withControlled orientation (achieved by using Controlled orientation (achieved by using sapphire and quartz) sapphire and quartz) Controlled position (achieved) Controlled position (achieved) Controlled density (achieved) Controlled density (achieved) Controlled diameter (ongoing)Controlled diameter (ongoing)Controlled Controlled chiralitychirality (ongoing)(ongoing)
-- Our Approach Our Approach A novel nanotubeA novel nanotube--onon--insulator (NOI) insulator (NOI) approach based on approach based on aligned nanotubesaligned nanotubes for for integrated nanotube circuitsintegrated nanotube circuits Nanotube
devicesNanotube
circuits
Quartz SubstrateCatalyst Particle
Quartz Substrate
Nanotube
One of the first to grow aligned nanotubes on sapphireOne of the first to grow aligned nanotubes on sapphireJ of Am Chem Soc 127 5294 J of Am Chem Soc 127 5294 -- 5295 (2005) 5295 (2005)
The first to make aligned nanotube transistorsThe first to make aligned nanotube transistorsNano Letters 6 34Nano Letters 6 34--39 (2006)39 (2006)Reported by Reported by Scientific AmericanScientific American (April 2006 P16) (April 2006 P16)
The first to demonstrate waferThe first to demonstrate wafer--scale processing of aligned scale processing of aligned nanotube devices and circuitsnanotube devices and circuits
Logic circuits (CMOS inverter NAND NOR)Logic circuits (CMOS inverter NAND NOR)
The first to make transparent nanotube devicesThe first to make transparent nanotube devicesACS Nano in press (2008)ACS Nano in press (2008)
Chip
1
2
3
4
5
Our Achievements on Aligned Single-Walled NanotubesOur Achievements on Aligned SingleOur Achievements on Aligned Single--Walled NanotubesWalled Nanotubes
Synthesis of Aligned Nanotubes on Sapphire QuartzSynthesis of Aligned Nanotubes on Sapphire Quartz
Gas in
Gas out
Sapphire with catalyst
Substrate Sapphire quartzCatalyst FerritinTemperature 900degCGas flow rate
CH4 2000 sccmC2H4 10 sccmH2 800 sccm
Generation IIFull Wafer Production
Generation IIFull Wafer Production
50 μm
2 0
1 5
1 0
5N
umbe
r
2 01 0D iam e te r (nm)500 nm
134 plusmn 030 nm
1 All nanotubes grow normal to the c axis on a-plane sapphire2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin11 All nanotubes grow normal to the c axis on aAll nanotubes grow normal to the c axis on a--plane sapphireplane sapphire2 Narrow diameter distribution of 2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin
c axis
Aligned Nanotubes Grown on a-Plane SapphireAligned Nanotubes Grown on a-Plane Sapphire
Zhou et al JACS 127 5294 (2005)
Zhou Zhou et alet al Nano Letters Nano Letters (2006)(2006)(Top ten hot articles in 2006)
High density SWNTsUp to 40 nanotubes μmInter-nanotube spacing ~ 25 nm
Low density SWNTs
Control of Nanotube DensityControl of Nanotube Density
Zhou et al JACS 127 5294 (2005) Zhou Zhou et alet al Nano Letters (2006) Nano Letters (2006)
a-plane
Red spheres oxygen atomsBlue spheres aluminum atomsPurple plane a-plane orientation
Hypothetic Schematic Diagram of SWNT on a-Plane SapphireHypothetic Schematic Diagram of SWNT on a-Plane Sapphire
Calculation of Lennard-Jones Potential Calculation of Lennard-Jones Potential
sumsum⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
minusminus⎟
⎟
⎠
⎞
⎜⎜
⎝
⎛
minus+
⎥⎥
⎦
⎤
⎢⎢
⎣
⎡
⎟⎟⎠
⎞⎜⎜⎝
⎛
minusminus⎟
⎟⎠
⎞⎜⎜⎝
⎛
minus=
j j
CAl
j
CAlCAl
i i
CO
i
COCO rrrrrrrr
rU
612612
44)( vvvvvvvvv σσ
εσσ
ε
a carbon atom and oxygen atoms in sapphire
a carbon atom and oxygen atoms in sapphire
a carbon atom and Al atoms in sapphire
a carbon atom and Al atoms in sapphire
Interaction between
Interaction between
C-plane C-plane a-plane a-plane
Potential wellPotential wellZhou Zhou et alet al JPCC JPCC 112 15929 (200(20088))
Synthesis of Nanotubes with Controlled Orientations and Positions
Synthesis of Nanotubes with Controlled Orientations and Positions
Catalyst
Photo Resist
QuartzSapphire
Catalyst Island
Aligned NanotubesMetal Electrode
SD
G
Dielectric Layer
3-10 nanotubes microm
Aligned Nanotubes on Quartz Using Patterned CatalystAligned Nanotubes on Quartz Using Patterned Catalystcatalyst
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
(a)
Poly Si Gate
Gate Oxide
SourceDrain Electrode
(b)
NanotubeGate Dielectric
Gate
SourceDrain Electrode
Comparison between Silicon-on-insulator (SOI) and Nanotube-on-Insulator (NOI)
Comparison between SiliconComparison between Silicon--onon--insulator (SOI) and insulator (SOI) and NanotubeNanotube--onon--Insulator (NOI)Insulator (NOI)
SOISOISOI NOINOINOI
Common Features1 Active material (Si or SWNT) is all over the surface2 Many devices can be patterned anywhere on the substrate3 Unwanted silicon or SWNTs can be removed via etching4 SOI and NOI offer minimized parasitic capacitance faster switching speed
and lower dynamic power consumption
Common FeaturesCommon Features11 Active material (Si or SWNT) is all over the surfaceActive material (Si or SWNT) is all over the surface22 Many devices can be patterned anywhere on the substrateMany devices can be patterned anywhere on the substrate33 Unwanted silicon or Unwanted silicon or SWNTsSWNTs can be removed via etchingcan be removed via etching44 SOI and NOI offer minimized parasitic capacitance faster switchSOI and NOI offer minimized parasitic capacitance faster switching speed ing speed
and lower dynamic power consumptionand lower dynamic power consumption Zhou et al Nano Letters (2006)
a-Sapphire
Wafer-Scale Aligned Nanotube SynthesisWafer-Scale Aligned Nanotube Synthesis
1200
1000
800
600
400
200
Tem
pera
ture
200150100500
Time (min)
Growth Annealing
Key meticulous temperature control amp uniform growth
1μm
Quartz 1000
800
600
400
200Tem
pera
ture
6004002000
Time (min)
Growth Annealing
1μm
4 inch substrate
Gas in
Gas out
Quartz or Sapphire with patterned
catalyst
9 feet-long growth furnace with three-zone
Wafer-Scale CNT TransferWafer-Scale CNT TransferTransfer fullTransfer full--wafer of wafer of CNTsCNTs from quartz growth substrate to SiOfrom quartz growth substrate to SiO22Si fabrication Si fabrication
substrate substrate allows largeallows large--scale integrationscale integration
Nano Lett 9 189ndash197 20094
Wafer-Scale Aligned Nanotube Device FabricationWafer-Scale Aligned Nanotube Device Fabrication
Back-Gated Submicron TransistorsBack-Gated Submicron Transistors
Back-gated transistors
1 microm
L = 1 microm
1 microm
L = 075 microm
1 microm
L = 05 microm
I-Vg curves Channel length dependence
-120
-100
-80
-60
-40
-20
0
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
-60
-40
-20
0
I ds (μ
Α)
-1500Vds (V)
-1 V
-08 V
-06 V
-04 V
-02 V
Vg from -8V to 8V
15
10
05
I ds (m
A)
-10 -5 0 5 10Vg (V)
L = 05 microm L = 075 microm L = 1 microm L = 2 microm L = 5 microm L = 10 microm L = 20 microm
80
60
40
20
gm
(μ S
)
5 6 7 81
2 3 4 5 6 7 810
2
L(μm)
2
4
6810-6
2
4
6810-5
I DW
(mA
microm
) gm
Ion Ioff
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Traditional approach On-Site Synthesis of Single-Walled Carbon Nanotubes
Traditional approach On-Site Synthesis of Single-Walled Carbon Nanotubes
SiSiO2
PMMA
Catalyst
CH4nanotube
Catalyst island
900 ordmC900 ordmC
metal electrode
H Dai et al Nature 395 878 (1998)
Infrastructure Nanotube CVD Generation IInfrastructure Nanotube CVD Generation I
1 μm
1 μm
26 nm in diameter
10 nm in diameter
High-quality nanotubes can be grown at specific positions
-60
-50
-40
-30
-20
-10
0
I DS(
nA)
-10-08-06-04-0200VDS(V)
Vg -4 V
0 V
2 V
6 V
Nanotube transistor can be easily produced
Si back gate
SiO2
S D
Integrated Nanotube SystemsComplementary Carbon Nanotube Inverter
Integrated Nanotube SystemsComplementary Carbon Nanotube Inverter
Carbon Nanotube Field-Effect Inverters X Liu R Lee J Han C Zhou Appl Phys Lett 79 3329 (2001)
One of the first integrated systems made of carbon nanotubes
Si back gate
K
Vin
Vout
VDD GND
p-type CNT n-type CNT
60
40
20
0
I DS(
nA)
-4 -2 0 2 4Vg(V)
VDS=10 mV
P type MOSFET12
8
4
0
I DS (
nA)
-4 -2 0 2 4Vg (V)
VDS=10 mV
N type MOSFET25
20
15
10
05
00
Vou
t(V)
252015100500Vin(V)
VDD=29 V
Vin Vout
0 V
VDD
p
n
Integrated Nanotube SystemsRing Oscillators Demonstrated by Avouris et al
Integrated Nanotube SystemsRing Oscillators Demonstrated by Avouris et al
Ph Avouris et al Science 311 1735 (2006)
Is there a way to assemble large quantities of nanotube devices
State-of-the-art of nanotube integration
Aligned Nanotubes for Devices and Circuits Aligned Nanotubes for Devices and Circuits
-- Project Mission Project Mission We want to tackle the challenging issue of We want to tackle the challenging issue of nanotube nanotube assembly and integrationassembly and integration
We want to grow carbon nanotubes withWe want to grow carbon nanotubes withControlled orientation (achieved by using Controlled orientation (achieved by using sapphire and quartz) sapphire and quartz) Controlled position (achieved) Controlled position (achieved) Controlled density (achieved) Controlled density (achieved) Controlled diameter (ongoing)Controlled diameter (ongoing)Controlled Controlled chiralitychirality (ongoing)(ongoing)
-- Our Approach Our Approach A novel nanotubeA novel nanotube--onon--insulator (NOI) insulator (NOI) approach based on approach based on aligned nanotubesaligned nanotubes for for integrated nanotube circuitsintegrated nanotube circuits Nanotube
devicesNanotube
circuits
Quartz SubstrateCatalyst Particle
Quartz Substrate
Nanotube
One of the first to grow aligned nanotubes on sapphireOne of the first to grow aligned nanotubes on sapphireJ of Am Chem Soc 127 5294 J of Am Chem Soc 127 5294 -- 5295 (2005) 5295 (2005)
The first to make aligned nanotube transistorsThe first to make aligned nanotube transistorsNano Letters 6 34Nano Letters 6 34--39 (2006)39 (2006)Reported by Reported by Scientific AmericanScientific American (April 2006 P16) (April 2006 P16)
The first to demonstrate waferThe first to demonstrate wafer--scale processing of aligned scale processing of aligned nanotube devices and circuitsnanotube devices and circuits
Logic circuits (CMOS inverter NAND NOR)Logic circuits (CMOS inverter NAND NOR)
The first to make transparent nanotube devicesThe first to make transparent nanotube devicesACS Nano in press (2008)ACS Nano in press (2008)
Chip
1
2
3
4
5
Our Achievements on Aligned Single-Walled NanotubesOur Achievements on Aligned SingleOur Achievements on Aligned Single--Walled NanotubesWalled Nanotubes
Synthesis of Aligned Nanotubes on Sapphire QuartzSynthesis of Aligned Nanotubes on Sapphire Quartz
Gas in
Gas out
Sapphire with catalyst
Substrate Sapphire quartzCatalyst FerritinTemperature 900degCGas flow rate
CH4 2000 sccmC2H4 10 sccmH2 800 sccm
Generation IIFull Wafer Production
Generation IIFull Wafer Production
50 μm
2 0
1 5
1 0
5N
umbe
r
2 01 0D iam e te r (nm)500 nm
134 plusmn 030 nm
1 All nanotubes grow normal to the c axis on a-plane sapphire2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin11 All nanotubes grow normal to the c axis on aAll nanotubes grow normal to the c axis on a--plane sapphireplane sapphire2 Narrow diameter distribution of 2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin
c axis
Aligned Nanotubes Grown on a-Plane SapphireAligned Nanotubes Grown on a-Plane Sapphire
Zhou et al JACS 127 5294 (2005)
Zhou Zhou et alet al Nano Letters Nano Letters (2006)(2006)(Top ten hot articles in 2006)
High density SWNTsUp to 40 nanotubes μmInter-nanotube spacing ~ 25 nm
Low density SWNTs
Control of Nanotube DensityControl of Nanotube Density
Zhou et al JACS 127 5294 (2005) Zhou Zhou et alet al Nano Letters (2006) Nano Letters (2006)
a-plane
Red spheres oxygen atomsBlue spheres aluminum atomsPurple plane a-plane orientation
Hypothetic Schematic Diagram of SWNT on a-Plane SapphireHypothetic Schematic Diagram of SWNT on a-Plane Sapphire
Calculation of Lennard-Jones Potential Calculation of Lennard-Jones Potential
sumsum⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
minusminus⎟
⎟
⎠
⎞
⎜⎜
⎝
⎛
minus+
⎥⎥
⎦
⎤
⎢⎢
⎣
⎡
⎟⎟⎠
⎞⎜⎜⎝
⎛
minusminus⎟
⎟⎠
⎞⎜⎜⎝
⎛
minus=
j j
CAl
j
CAlCAl
i i
CO
i
COCO rrrrrrrr
rU
612612
44)( vvvvvvvvv σσ
εσσ
ε
a carbon atom and oxygen atoms in sapphire
a carbon atom and oxygen atoms in sapphire
a carbon atom and Al atoms in sapphire
a carbon atom and Al atoms in sapphire
Interaction between
Interaction between
C-plane C-plane a-plane a-plane
Potential wellPotential wellZhou Zhou et alet al JPCC JPCC 112 15929 (200(20088))
Synthesis of Nanotubes with Controlled Orientations and Positions
Synthesis of Nanotubes with Controlled Orientations and Positions
Catalyst
Photo Resist
QuartzSapphire
Catalyst Island
Aligned NanotubesMetal Electrode
SD
G
Dielectric Layer
3-10 nanotubes microm
Aligned Nanotubes on Quartz Using Patterned CatalystAligned Nanotubes on Quartz Using Patterned Catalystcatalyst
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
(a)
Poly Si Gate
Gate Oxide
SourceDrain Electrode
(b)
NanotubeGate Dielectric
Gate
SourceDrain Electrode
Comparison between Silicon-on-insulator (SOI) and Nanotube-on-Insulator (NOI)
Comparison between SiliconComparison between Silicon--onon--insulator (SOI) and insulator (SOI) and NanotubeNanotube--onon--Insulator (NOI)Insulator (NOI)
SOISOISOI NOINOINOI
Common Features1 Active material (Si or SWNT) is all over the surface2 Many devices can be patterned anywhere on the substrate3 Unwanted silicon or SWNTs can be removed via etching4 SOI and NOI offer minimized parasitic capacitance faster switching speed
and lower dynamic power consumption
Common FeaturesCommon Features11 Active material (Si or SWNT) is all over the surfaceActive material (Si or SWNT) is all over the surface22 Many devices can be patterned anywhere on the substrateMany devices can be patterned anywhere on the substrate33 Unwanted silicon or Unwanted silicon or SWNTsSWNTs can be removed via etchingcan be removed via etching44 SOI and NOI offer minimized parasitic capacitance faster switchSOI and NOI offer minimized parasitic capacitance faster switching speed ing speed
and lower dynamic power consumptionand lower dynamic power consumption Zhou et al Nano Letters (2006)
a-Sapphire
Wafer-Scale Aligned Nanotube SynthesisWafer-Scale Aligned Nanotube Synthesis
1200
1000
800
600
400
200
Tem
pera
ture
200150100500
Time (min)
Growth Annealing
Key meticulous temperature control amp uniform growth
1μm
Quartz 1000
800
600
400
200Tem
pera
ture
6004002000
Time (min)
Growth Annealing
1μm
4 inch substrate
Gas in
Gas out
Quartz or Sapphire with patterned
catalyst
9 feet-long growth furnace with three-zone
Wafer-Scale CNT TransferWafer-Scale CNT TransferTransfer fullTransfer full--wafer of wafer of CNTsCNTs from quartz growth substrate to SiOfrom quartz growth substrate to SiO22Si fabrication Si fabrication
substrate substrate allows largeallows large--scale integrationscale integration
Nano Lett 9 189ndash197 20094
Wafer-Scale Aligned Nanotube Device FabricationWafer-Scale Aligned Nanotube Device Fabrication
Back-Gated Submicron TransistorsBack-Gated Submicron Transistors
Back-gated transistors
1 microm
L = 1 microm
1 microm
L = 075 microm
1 microm
L = 05 microm
I-Vg curves Channel length dependence
-120
-100
-80
-60
-40
-20
0
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
-60
-40
-20
0
I ds (μ
Α)
-1500Vds (V)
-1 V
-08 V
-06 V
-04 V
-02 V
Vg from -8V to 8V
15
10
05
I ds (m
A)
-10 -5 0 5 10Vg (V)
L = 05 microm L = 075 microm L = 1 microm L = 2 microm L = 5 microm L = 10 microm L = 20 microm
80
60
40
20
gm
(μ S
)
5 6 7 81
2 3 4 5 6 7 810
2
L(μm)
2
4
6810-6
2
4
6810-5
I DW
(mA
microm
) gm
Ion Ioff
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Traditional approach On-Site Synthesis of Single-Walled Carbon Nanotubes
Traditional approach On-Site Synthesis of Single-Walled Carbon Nanotubes
SiSiO2
PMMA
Catalyst
CH4nanotube
Catalyst island
900 ordmC900 ordmC
metal electrode
H Dai et al Nature 395 878 (1998)
Infrastructure Nanotube CVD Generation IInfrastructure Nanotube CVD Generation I
1 μm
1 μm
26 nm in diameter
10 nm in diameter
High-quality nanotubes can be grown at specific positions
-60
-50
-40
-30
-20
-10
0
I DS(
nA)
-10-08-06-04-0200VDS(V)
Vg -4 V
0 V
2 V
6 V
Nanotube transistor can be easily produced
Si back gate
SiO2
S D
Integrated Nanotube SystemsComplementary Carbon Nanotube Inverter
Integrated Nanotube SystemsComplementary Carbon Nanotube Inverter
Carbon Nanotube Field-Effect Inverters X Liu R Lee J Han C Zhou Appl Phys Lett 79 3329 (2001)
One of the first integrated systems made of carbon nanotubes
Si back gate
K
Vin
Vout
VDD GND
p-type CNT n-type CNT
60
40
20
0
I DS(
nA)
-4 -2 0 2 4Vg(V)
VDS=10 mV
P type MOSFET12
8
4
0
I DS (
nA)
-4 -2 0 2 4Vg (V)
VDS=10 mV
N type MOSFET25
20
15
10
05
00
Vou
t(V)
252015100500Vin(V)
VDD=29 V
Vin Vout
0 V
VDD
p
n
Integrated Nanotube SystemsRing Oscillators Demonstrated by Avouris et al
Integrated Nanotube SystemsRing Oscillators Demonstrated by Avouris et al
Ph Avouris et al Science 311 1735 (2006)
Is there a way to assemble large quantities of nanotube devices
State-of-the-art of nanotube integration
Aligned Nanotubes for Devices and Circuits Aligned Nanotubes for Devices and Circuits
-- Project Mission Project Mission We want to tackle the challenging issue of We want to tackle the challenging issue of nanotube nanotube assembly and integrationassembly and integration
We want to grow carbon nanotubes withWe want to grow carbon nanotubes withControlled orientation (achieved by using Controlled orientation (achieved by using sapphire and quartz) sapphire and quartz) Controlled position (achieved) Controlled position (achieved) Controlled density (achieved) Controlled density (achieved) Controlled diameter (ongoing)Controlled diameter (ongoing)Controlled Controlled chiralitychirality (ongoing)(ongoing)
-- Our Approach Our Approach A novel nanotubeA novel nanotube--onon--insulator (NOI) insulator (NOI) approach based on approach based on aligned nanotubesaligned nanotubes for for integrated nanotube circuitsintegrated nanotube circuits Nanotube
devicesNanotube
circuits
Quartz SubstrateCatalyst Particle
Quartz Substrate
Nanotube
One of the first to grow aligned nanotubes on sapphireOne of the first to grow aligned nanotubes on sapphireJ of Am Chem Soc 127 5294 J of Am Chem Soc 127 5294 -- 5295 (2005) 5295 (2005)
The first to make aligned nanotube transistorsThe first to make aligned nanotube transistorsNano Letters 6 34Nano Letters 6 34--39 (2006)39 (2006)Reported by Reported by Scientific AmericanScientific American (April 2006 P16) (April 2006 P16)
The first to demonstrate waferThe first to demonstrate wafer--scale processing of aligned scale processing of aligned nanotube devices and circuitsnanotube devices and circuits
Logic circuits (CMOS inverter NAND NOR)Logic circuits (CMOS inverter NAND NOR)
The first to make transparent nanotube devicesThe first to make transparent nanotube devicesACS Nano in press (2008)ACS Nano in press (2008)
Chip
1
2
3
4
5
Our Achievements on Aligned Single-Walled NanotubesOur Achievements on Aligned SingleOur Achievements on Aligned Single--Walled NanotubesWalled Nanotubes
Synthesis of Aligned Nanotubes on Sapphire QuartzSynthesis of Aligned Nanotubes on Sapphire Quartz
Gas in
Gas out
Sapphire with catalyst
Substrate Sapphire quartzCatalyst FerritinTemperature 900degCGas flow rate
CH4 2000 sccmC2H4 10 sccmH2 800 sccm
Generation IIFull Wafer Production
Generation IIFull Wafer Production
50 μm
2 0
1 5
1 0
5N
umbe
r
2 01 0D iam e te r (nm)500 nm
134 plusmn 030 nm
1 All nanotubes grow normal to the c axis on a-plane sapphire2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin11 All nanotubes grow normal to the c axis on aAll nanotubes grow normal to the c axis on a--plane sapphireplane sapphire2 Narrow diameter distribution of 2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin
c axis
Aligned Nanotubes Grown on a-Plane SapphireAligned Nanotubes Grown on a-Plane Sapphire
Zhou et al JACS 127 5294 (2005)
Zhou Zhou et alet al Nano Letters Nano Letters (2006)(2006)(Top ten hot articles in 2006)
High density SWNTsUp to 40 nanotubes μmInter-nanotube spacing ~ 25 nm
Low density SWNTs
Control of Nanotube DensityControl of Nanotube Density
Zhou et al JACS 127 5294 (2005) Zhou Zhou et alet al Nano Letters (2006) Nano Letters (2006)
a-plane
Red spheres oxygen atomsBlue spheres aluminum atomsPurple plane a-plane orientation
Hypothetic Schematic Diagram of SWNT on a-Plane SapphireHypothetic Schematic Diagram of SWNT on a-Plane Sapphire
Calculation of Lennard-Jones Potential Calculation of Lennard-Jones Potential
sumsum⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
minusminus⎟
⎟
⎠
⎞
⎜⎜
⎝
⎛
minus+
⎥⎥
⎦
⎤
⎢⎢
⎣
⎡
⎟⎟⎠
⎞⎜⎜⎝
⎛
minusminus⎟
⎟⎠
⎞⎜⎜⎝
⎛
minus=
j j
CAl
j
CAlCAl
i i
CO
i
COCO rrrrrrrr
rU
612612
44)( vvvvvvvvv σσ
εσσ
ε
a carbon atom and oxygen atoms in sapphire
a carbon atom and oxygen atoms in sapphire
a carbon atom and Al atoms in sapphire
a carbon atom and Al atoms in sapphire
Interaction between
Interaction between
C-plane C-plane a-plane a-plane
Potential wellPotential wellZhou Zhou et alet al JPCC JPCC 112 15929 (200(20088))
Synthesis of Nanotubes with Controlled Orientations and Positions
Synthesis of Nanotubes with Controlled Orientations and Positions
Catalyst
Photo Resist
QuartzSapphire
Catalyst Island
Aligned NanotubesMetal Electrode
SD
G
Dielectric Layer
3-10 nanotubes microm
Aligned Nanotubes on Quartz Using Patterned CatalystAligned Nanotubes on Quartz Using Patterned Catalystcatalyst
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
(a)
Poly Si Gate
Gate Oxide
SourceDrain Electrode
(b)
NanotubeGate Dielectric
Gate
SourceDrain Electrode
Comparison between Silicon-on-insulator (SOI) and Nanotube-on-Insulator (NOI)
Comparison between SiliconComparison between Silicon--onon--insulator (SOI) and insulator (SOI) and NanotubeNanotube--onon--Insulator (NOI)Insulator (NOI)
SOISOISOI NOINOINOI
Common Features1 Active material (Si or SWNT) is all over the surface2 Many devices can be patterned anywhere on the substrate3 Unwanted silicon or SWNTs can be removed via etching4 SOI and NOI offer minimized parasitic capacitance faster switching speed
and lower dynamic power consumption
Common FeaturesCommon Features11 Active material (Si or SWNT) is all over the surfaceActive material (Si or SWNT) is all over the surface22 Many devices can be patterned anywhere on the substrateMany devices can be patterned anywhere on the substrate33 Unwanted silicon or Unwanted silicon or SWNTsSWNTs can be removed via etchingcan be removed via etching44 SOI and NOI offer minimized parasitic capacitance faster switchSOI and NOI offer minimized parasitic capacitance faster switching speed ing speed
and lower dynamic power consumptionand lower dynamic power consumption Zhou et al Nano Letters (2006)
a-Sapphire
Wafer-Scale Aligned Nanotube SynthesisWafer-Scale Aligned Nanotube Synthesis
1200
1000
800
600
400
200
Tem
pera
ture
200150100500
Time (min)
Growth Annealing
Key meticulous temperature control amp uniform growth
1μm
Quartz 1000
800
600
400
200Tem
pera
ture
6004002000
Time (min)
Growth Annealing
1μm
4 inch substrate
Gas in
Gas out
Quartz or Sapphire with patterned
catalyst
9 feet-long growth furnace with three-zone
Wafer-Scale CNT TransferWafer-Scale CNT TransferTransfer fullTransfer full--wafer of wafer of CNTsCNTs from quartz growth substrate to SiOfrom quartz growth substrate to SiO22Si fabrication Si fabrication
substrate substrate allows largeallows large--scale integrationscale integration
Nano Lett 9 189ndash197 20094
Wafer-Scale Aligned Nanotube Device FabricationWafer-Scale Aligned Nanotube Device Fabrication
Back-Gated Submicron TransistorsBack-Gated Submicron Transistors
Back-gated transistors
1 microm
L = 1 microm
1 microm
L = 075 microm
1 microm
L = 05 microm
I-Vg curves Channel length dependence
-120
-100
-80
-60
-40
-20
0
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
-60
-40
-20
0
I ds (μ
Α)
-1500Vds (V)
-1 V
-08 V
-06 V
-04 V
-02 V
Vg from -8V to 8V
15
10
05
I ds (m
A)
-10 -5 0 5 10Vg (V)
L = 05 microm L = 075 microm L = 1 microm L = 2 microm L = 5 microm L = 10 microm L = 20 microm
80
60
40
20
gm
(μ S
)
5 6 7 81
2 3 4 5 6 7 810
2
L(μm)
2
4
6810-6
2
4
6810-5
I DW
(mA
microm
) gm
Ion Ioff
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Infrastructure Nanotube CVD Generation IInfrastructure Nanotube CVD Generation I
1 μm
1 μm
26 nm in diameter
10 nm in diameter
High-quality nanotubes can be grown at specific positions
-60
-50
-40
-30
-20
-10
0
I DS(
nA)
-10-08-06-04-0200VDS(V)
Vg -4 V
0 V
2 V
6 V
Nanotube transistor can be easily produced
Si back gate
SiO2
S D
Integrated Nanotube SystemsComplementary Carbon Nanotube Inverter
Integrated Nanotube SystemsComplementary Carbon Nanotube Inverter
Carbon Nanotube Field-Effect Inverters X Liu R Lee J Han C Zhou Appl Phys Lett 79 3329 (2001)
One of the first integrated systems made of carbon nanotubes
Si back gate
K
Vin
Vout
VDD GND
p-type CNT n-type CNT
60
40
20
0
I DS(
nA)
-4 -2 0 2 4Vg(V)
VDS=10 mV
P type MOSFET12
8
4
0
I DS (
nA)
-4 -2 0 2 4Vg (V)
VDS=10 mV
N type MOSFET25
20
15
10
05
00
Vou
t(V)
252015100500Vin(V)
VDD=29 V
Vin Vout
0 V
VDD
p
n
Integrated Nanotube SystemsRing Oscillators Demonstrated by Avouris et al
Integrated Nanotube SystemsRing Oscillators Demonstrated by Avouris et al
Ph Avouris et al Science 311 1735 (2006)
Is there a way to assemble large quantities of nanotube devices
State-of-the-art of nanotube integration
Aligned Nanotubes for Devices and Circuits Aligned Nanotubes for Devices and Circuits
-- Project Mission Project Mission We want to tackle the challenging issue of We want to tackle the challenging issue of nanotube nanotube assembly and integrationassembly and integration
We want to grow carbon nanotubes withWe want to grow carbon nanotubes withControlled orientation (achieved by using Controlled orientation (achieved by using sapphire and quartz) sapphire and quartz) Controlled position (achieved) Controlled position (achieved) Controlled density (achieved) Controlled density (achieved) Controlled diameter (ongoing)Controlled diameter (ongoing)Controlled Controlled chiralitychirality (ongoing)(ongoing)
-- Our Approach Our Approach A novel nanotubeA novel nanotube--onon--insulator (NOI) insulator (NOI) approach based on approach based on aligned nanotubesaligned nanotubes for for integrated nanotube circuitsintegrated nanotube circuits Nanotube
devicesNanotube
circuits
Quartz SubstrateCatalyst Particle
Quartz Substrate
Nanotube
One of the first to grow aligned nanotubes on sapphireOne of the first to grow aligned nanotubes on sapphireJ of Am Chem Soc 127 5294 J of Am Chem Soc 127 5294 -- 5295 (2005) 5295 (2005)
The first to make aligned nanotube transistorsThe first to make aligned nanotube transistorsNano Letters 6 34Nano Letters 6 34--39 (2006)39 (2006)Reported by Reported by Scientific AmericanScientific American (April 2006 P16) (April 2006 P16)
The first to demonstrate waferThe first to demonstrate wafer--scale processing of aligned scale processing of aligned nanotube devices and circuitsnanotube devices and circuits
Logic circuits (CMOS inverter NAND NOR)Logic circuits (CMOS inverter NAND NOR)
The first to make transparent nanotube devicesThe first to make transparent nanotube devicesACS Nano in press (2008)ACS Nano in press (2008)
Chip
1
2
3
4
5
Our Achievements on Aligned Single-Walled NanotubesOur Achievements on Aligned SingleOur Achievements on Aligned Single--Walled NanotubesWalled Nanotubes
Synthesis of Aligned Nanotubes on Sapphire QuartzSynthesis of Aligned Nanotubes on Sapphire Quartz
Gas in
Gas out
Sapphire with catalyst
Substrate Sapphire quartzCatalyst FerritinTemperature 900degCGas flow rate
CH4 2000 sccmC2H4 10 sccmH2 800 sccm
Generation IIFull Wafer Production
Generation IIFull Wafer Production
50 μm
2 0
1 5
1 0
5N
umbe
r
2 01 0D iam e te r (nm)500 nm
134 plusmn 030 nm
1 All nanotubes grow normal to the c axis on a-plane sapphire2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin11 All nanotubes grow normal to the c axis on aAll nanotubes grow normal to the c axis on a--plane sapphireplane sapphire2 Narrow diameter distribution of 2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin
c axis
Aligned Nanotubes Grown on a-Plane SapphireAligned Nanotubes Grown on a-Plane Sapphire
Zhou et al JACS 127 5294 (2005)
Zhou Zhou et alet al Nano Letters Nano Letters (2006)(2006)(Top ten hot articles in 2006)
High density SWNTsUp to 40 nanotubes μmInter-nanotube spacing ~ 25 nm
Low density SWNTs
Control of Nanotube DensityControl of Nanotube Density
Zhou et al JACS 127 5294 (2005) Zhou Zhou et alet al Nano Letters (2006) Nano Letters (2006)
a-plane
Red spheres oxygen atomsBlue spheres aluminum atomsPurple plane a-plane orientation
Hypothetic Schematic Diagram of SWNT on a-Plane SapphireHypothetic Schematic Diagram of SWNT on a-Plane Sapphire
Calculation of Lennard-Jones Potential Calculation of Lennard-Jones Potential
sumsum⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
minusminus⎟
⎟
⎠
⎞
⎜⎜
⎝
⎛
minus+
⎥⎥
⎦
⎤
⎢⎢
⎣
⎡
⎟⎟⎠
⎞⎜⎜⎝
⎛
minusminus⎟
⎟⎠
⎞⎜⎜⎝
⎛
minus=
j j
CAl
j
CAlCAl
i i
CO
i
COCO rrrrrrrr
rU
612612
44)( vvvvvvvvv σσ
εσσ
ε
a carbon atom and oxygen atoms in sapphire
a carbon atom and oxygen atoms in sapphire
a carbon atom and Al atoms in sapphire
a carbon atom and Al atoms in sapphire
Interaction between
Interaction between
C-plane C-plane a-plane a-plane
Potential wellPotential wellZhou Zhou et alet al JPCC JPCC 112 15929 (200(20088))
Synthesis of Nanotubes with Controlled Orientations and Positions
Synthesis of Nanotubes with Controlled Orientations and Positions
Catalyst
Photo Resist
QuartzSapphire
Catalyst Island
Aligned NanotubesMetal Electrode
SD
G
Dielectric Layer
3-10 nanotubes microm
Aligned Nanotubes on Quartz Using Patterned CatalystAligned Nanotubes on Quartz Using Patterned Catalystcatalyst
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
(a)
Poly Si Gate
Gate Oxide
SourceDrain Electrode
(b)
NanotubeGate Dielectric
Gate
SourceDrain Electrode
Comparison between Silicon-on-insulator (SOI) and Nanotube-on-Insulator (NOI)
Comparison between SiliconComparison between Silicon--onon--insulator (SOI) and insulator (SOI) and NanotubeNanotube--onon--Insulator (NOI)Insulator (NOI)
SOISOISOI NOINOINOI
Common Features1 Active material (Si or SWNT) is all over the surface2 Many devices can be patterned anywhere on the substrate3 Unwanted silicon or SWNTs can be removed via etching4 SOI and NOI offer minimized parasitic capacitance faster switching speed
and lower dynamic power consumption
Common FeaturesCommon Features11 Active material (Si or SWNT) is all over the surfaceActive material (Si or SWNT) is all over the surface22 Many devices can be patterned anywhere on the substrateMany devices can be patterned anywhere on the substrate33 Unwanted silicon or Unwanted silicon or SWNTsSWNTs can be removed via etchingcan be removed via etching44 SOI and NOI offer minimized parasitic capacitance faster switchSOI and NOI offer minimized parasitic capacitance faster switching speed ing speed
and lower dynamic power consumptionand lower dynamic power consumption Zhou et al Nano Letters (2006)
a-Sapphire
Wafer-Scale Aligned Nanotube SynthesisWafer-Scale Aligned Nanotube Synthesis
1200
1000
800
600
400
200
Tem
pera
ture
200150100500
Time (min)
Growth Annealing
Key meticulous temperature control amp uniform growth
1μm
Quartz 1000
800
600
400
200Tem
pera
ture
6004002000
Time (min)
Growth Annealing
1μm
4 inch substrate
Gas in
Gas out
Quartz or Sapphire with patterned
catalyst
9 feet-long growth furnace with three-zone
Wafer-Scale CNT TransferWafer-Scale CNT TransferTransfer fullTransfer full--wafer of wafer of CNTsCNTs from quartz growth substrate to SiOfrom quartz growth substrate to SiO22Si fabrication Si fabrication
substrate substrate allows largeallows large--scale integrationscale integration
Nano Lett 9 189ndash197 20094
Wafer-Scale Aligned Nanotube Device FabricationWafer-Scale Aligned Nanotube Device Fabrication
Back-Gated Submicron TransistorsBack-Gated Submicron Transistors
Back-gated transistors
1 microm
L = 1 microm
1 microm
L = 075 microm
1 microm
L = 05 microm
I-Vg curves Channel length dependence
-120
-100
-80
-60
-40
-20
0
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
-60
-40
-20
0
I ds (μ
Α)
-1500Vds (V)
-1 V
-08 V
-06 V
-04 V
-02 V
Vg from -8V to 8V
15
10
05
I ds (m
A)
-10 -5 0 5 10Vg (V)
L = 05 microm L = 075 microm L = 1 microm L = 2 microm L = 5 microm L = 10 microm L = 20 microm
80
60
40
20
gm
(μ S
)
5 6 7 81
2 3 4 5 6 7 810
2
L(μm)
2
4
6810-6
2
4
6810-5
I DW
(mA
microm
) gm
Ion Ioff
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Integrated Nanotube SystemsComplementary Carbon Nanotube Inverter
Integrated Nanotube SystemsComplementary Carbon Nanotube Inverter
Carbon Nanotube Field-Effect Inverters X Liu R Lee J Han C Zhou Appl Phys Lett 79 3329 (2001)
One of the first integrated systems made of carbon nanotubes
Si back gate
K
Vin
Vout
VDD GND
p-type CNT n-type CNT
60
40
20
0
I DS(
nA)
-4 -2 0 2 4Vg(V)
VDS=10 mV
P type MOSFET12
8
4
0
I DS (
nA)
-4 -2 0 2 4Vg (V)
VDS=10 mV
N type MOSFET25
20
15
10
05
00
Vou
t(V)
252015100500Vin(V)
VDD=29 V
Vin Vout
0 V
VDD
p
n
Integrated Nanotube SystemsRing Oscillators Demonstrated by Avouris et al
Integrated Nanotube SystemsRing Oscillators Demonstrated by Avouris et al
Ph Avouris et al Science 311 1735 (2006)
Is there a way to assemble large quantities of nanotube devices
State-of-the-art of nanotube integration
Aligned Nanotubes for Devices and Circuits Aligned Nanotubes for Devices and Circuits
-- Project Mission Project Mission We want to tackle the challenging issue of We want to tackle the challenging issue of nanotube nanotube assembly and integrationassembly and integration
We want to grow carbon nanotubes withWe want to grow carbon nanotubes withControlled orientation (achieved by using Controlled orientation (achieved by using sapphire and quartz) sapphire and quartz) Controlled position (achieved) Controlled position (achieved) Controlled density (achieved) Controlled density (achieved) Controlled diameter (ongoing)Controlled diameter (ongoing)Controlled Controlled chiralitychirality (ongoing)(ongoing)
-- Our Approach Our Approach A novel nanotubeA novel nanotube--onon--insulator (NOI) insulator (NOI) approach based on approach based on aligned nanotubesaligned nanotubes for for integrated nanotube circuitsintegrated nanotube circuits Nanotube
devicesNanotube
circuits
Quartz SubstrateCatalyst Particle
Quartz Substrate
Nanotube
One of the first to grow aligned nanotubes on sapphireOne of the first to grow aligned nanotubes on sapphireJ of Am Chem Soc 127 5294 J of Am Chem Soc 127 5294 -- 5295 (2005) 5295 (2005)
The first to make aligned nanotube transistorsThe first to make aligned nanotube transistorsNano Letters 6 34Nano Letters 6 34--39 (2006)39 (2006)Reported by Reported by Scientific AmericanScientific American (April 2006 P16) (April 2006 P16)
The first to demonstrate waferThe first to demonstrate wafer--scale processing of aligned scale processing of aligned nanotube devices and circuitsnanotube devices and circuits
Logic circuits (CMOS inverter NAND NOR)Logic circuits (CMOS inverter NAND NOR)
The first to make transparent nanotube devicesThe first to make transparent nanotube devicesACS Nano in press (2008)ACS Nano in press (2008)
Chip
1
2
3
4
5
Our Achievements on Aligned Single-Walled NanotubesOur Achievements on Aligned SingleOur Achievements on Aligned Single--Walled NanotubesWalled Nanotubes
Synthesis of Aligned Nanotubes on Sapphire QuartzSynthesis of Aligned Nanotubes on Sapphire Quartz
Gas in
Gas out
Sapphire with catalyst
Substrate Sapphire quartzCatalyst FerritinTemperature 900degCGas flow rate
CH4 2000 sccmC2H4 10 sccmH2 800 sccm
Generation IIFull Wafer Production
Generation IIFull Wafer Production
50 μm
2 0
1 5
1 0
5N
umbe
r
2 01 0D iam e te r (nm)500 nm
134 plusmn 030 nm
1 All nanotubes grow normal to the c axis on a-plane sapphire2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin11 All nanotubes grow normal to the c axis on aAll nanotubes grow normal to the c axis on a--plane sapphireplane sapphire2 Narrow diameter distribution of 2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin
c axis
Aligned Nanotubes Grown on a-Plane SapphireAligned Nanotubes Grown on a-Plane Sapphire
Zhou et al JACS 127 5294 (2005)
Zhou Zhou et alet al Nano Letters Nano Letters (2006)(2006)(Top ten hot articles in 2006)
High density SWNTsUp to 40 nanotubes μmInter-nanotube spacing ~ 25 nm
Low density SWNTs
Control of Nanotube DensityControl of Nanotube Density
Zhou et al JACS 127 5294 (2005) Zhou Zhou et alet al Nano Letters (2006) Nano Letters (2006)
a-plane
Red spheres oxygen atomsBlue spheres aluminum atomsPurple plane a-plane orientation
Hypothetic Schematic Diagram of SWNT on a-Plane SapphireHypothetic Schematic Diagram of SWNT on a-Plane Sapphire
Calculation of Lennard-Jones Potential Calculation of Lennard-Jones Potential
sumsum⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
minusminus⎟
⎟
⎠
⎞
⎜⎜
⎝
⎛
minus+
⎥⎥
⎦
⎤
⎢⎢
⎣
⎡
⎟⎟⎠
⎞⎜⎜⎝
⎛
minusminus⎟
⎟⎠
⎞⎜⎜⎝
⎛
minus=
j j
CAl
j
CAlCAl
i i
CO
i
COCO rrrrrrrr
rU
612612
44)( vvvvvvvvv σσ
εσσ
ε
a carbon atom and oxygen atoms in sapphire
a carbon atom and oxygen atoms in sapphire
a carbon atom and Al atoms in sapphire
a carbon atom and Al atoms in sapphire
Interaction between
Interaction between
C-plane C-plane a-plane a-plane
Potential wellPotential wellZhou Zhou et alet al JPCC JPCC 112 15929 (200(20088))
Synthesis of Nanotubes with Controlled Orientations and Positions
Synthesis of Nanotubes with Controlled Orientations and Positions
Catalyst
Photo Resist
QuartzSapphire
Catalyst Island
Aligned NanotubesMetal Electrode
SD
G
Dielectric Layer
3-10 nanotubes microm
Aligned Nanotubes on Quartz Using Patterned CatalystAligned Nanotubes on Quartz Using Patterned Catalystcatalyst
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
(a)
Poly Si Gate
Gate Oxide
SourceDrain Electrode
(b)
NanotubeGate Dielectric
Gate
SourceDrain Electrode
Comparison between Silicon-on-insulator (SOI) and Nanotube-on-Insulator (NOI)
Comparison between SiliconComparison between Silicon--onon--insulator (SOI) and insulator (SOI) and NanotubeNanotube--onon--Insulator (NOI)Insulator (NOI)
SOISOISOI NOINOINOI
Common Features1 Active material (Si or SWNT) is all over the surface2 Many devices can be patterned anywhere on the substrate3 Unwanted silicon or SWNTs can be removed via etching4 SOI and NOI offer minimized parasitic capacitance faster switching speed
and lower dynamic power consumption
Common FeaturesCommon Features11 Active material (Si or SWNT) is all over the surfaceActive material (Si or SWNT) is all over the surface22 Many devices can be patterned anywhere on the substrateMany devices can be patterned anywhere on the substrate33 Unwanted silicon or Unwanted silicon or SWNTsSWNTs can be removed via etchingcan be removed via etching44 SOI and NOI offer minimized parasitic capacitance faster switchSOI and NOI offer minimized parasitic capacitance faster switching speed ing speed
and lower dynamic power consumptionand lower dynamic power consumption Zhou et al Nano Letters (2006)
a-Sapphire
Wafer-Scale Aligned Nanotube SynthesisWafer-Scale Aligned Nanotube Synthesis
1200
1000
800
600
400
200
Tem
pera
ture
200150100500
Time (min)
Growth Annealing
Key meticulous temperature control amp uniform growth
1μm
Quartz 1000
800
600
400
200Tem
pera
ture
6004002000
Time (min)
Growth Annealing
1μm
4 inch substrate
Gas in
Gas out
Quartz or Sapphire with patterned
catalyst
9 feet-long growth furnace with three-zone
Wafer-Scale CNT TransferWafer-Scale CNT TransferTransfer fullTransfer full--wafer of wafer of CNTsCNTs from quartz growth substrate to SiOfrom quartz growth substrate to SiO22Si fabrication Si fabrication
substrate substrate allows largeallows large--scale integrationscale integration
Nano Lett 9 189ndash197 20094
Wafer-Scale Aligned Nanotube Device FabricationWafer-Scale Aligned Nanotube Device Fabrication
Back-Gated Submicron TransistorsBack-Gated Submicron Transistors
Back-gated transistors
1 microm
L = 1 microm
1 microm
L = 075 microm
1 microm
L = 05 microm
I-Vg curves Channel length dependence
-120
-100
-80
-60
-40
-20
0
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
-60
-40
-20
0
I ds (μ
Α)
-1500Vds (V)
-1 V
-08 V
-06 V
-04 V
-02 V
Vg from -8V to 8V
15
10
05
I ds (m
A)
-10 -5 0 5 10Vg (V)
L = 05 microm L = 075 microm L = 1 microm L = 2 microm L = 5 microm L = 10 microm L = 20 microm
80
60
40
20
gm
(μ S
)
5 6 7 81
2 3 4 5 6 7 810
2
L(μm)
2
4
6810-6
2
4
6810-5
I DW
(mA
microm
) gm
Ion Ioff
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Integrated Nanotube SystemsRing Oscillators Demonstrated by Avouris et al
Integrated Nanotube SystemsRing Oscillators Demonstrated by Avouris et al
Ph Avouris et al Science 311 1735 (2006)
Is there a way to assemble large quantities of nanotube devices
State-of-the-art of nanotube integration
Aligned Nanotubes for Devices and Circuits Aligned Nanotubes for Devices and Circuits
-- Project Mission Project Mission We want to tackle the challenging issue of We want to tackle the challenging issue of nanotube nanotube assembly and integrationassembly and integration
We want to grow carbon nanotubes withWe want to grow carbon nanotubes withControlled orientation (achieved by using Controlled orientation (achieved by using sapphire and quartz) sapphire and quartz) Controlled position (achieved) Controlled position (achieved) Controlled density (achieved) Controlled density (achieved) Controlled diameter (ongoing)Controlled diameter (ongoing)Controlled Controlled chiralitychirality (ongoing)(ongoing)
-- Our Approach Our Approach A novel nanotubeA novel nanotube--onon--insulator (NOI) insulator (NOI) approach based on approach based on aligned nanotubesaligned nanotubes for for integrated nanotube circuitsintegrated nanotube circuits Nanotube
devicesNanotube
circuits
Quartz SubstrateCatalyst Particle
Quartz Substrate
Nanotube
One of the first to grow aligned nanotubes on sapphireOne of the first to grow aligned nanotubes on sapphireJ of Am Chem Soc 127 5294 J of Am Chem Soc 127 5294 -- 5295 (2005) 5295 (2005)
The first to make aligned nanotube transistorsThe first to make aligned nanotube transistorsNano Letters 6 34Nano Letters 6 34--39 (2006)39 (2006)Reported by Reported by Scientific AmericanScientific American (April 2006 P16) (April 2006 P16)
The first to demonstrate waferThe first to demonstrate wafer--scale processing of aligned scale processing of aligned nanotube devices and circuitsnanotube devices and circuits
Logic circuits (CMOS inverter NAND NOR)Logic circuits (CMOS inverter NAND NOR)
The first to make transparent nanotube devicesThe first to make transparent nanotube devicesACS Nano in press (2008)ACS Nano in press (2008)
Chip
1
2
3
4
5
Our Achievements on Aligned Single-Walled NanotubesOur Achievements on Aligned SingleOur Achievements on Aligned Single--Walled NanotubesWalled Nanotubes
Synthesis of Aligned Nanotubes on Sapphire QuartzSynthesis of Aligned Nanotubes on Sapphire Quartz
Gas in
Gas out
Sapphire with catalyst
Substrate Sapphire quartzCatalyst FerritinTemperature 900degCGas flow rate
CH4 2000 sccmC2H4 10 sccmH2 800 sccm
Generation IIFull Wafer Production
Generation IIFull Wafer Production
50 μm
2 0
1 5
1 0
5N
umbe
r
2 01 0D iam e te r (nm)500 nm
134 plusmn 030 nm
1 All nanotubes grow normal to the c axis on a-plane sapphire2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin11 All nanotubes grow normal to the c axis on aAll nanotubes grow normal to the c axis on a--plane sapphireplane sapphire2 Narrow diameter distribution of 2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin
c axis
Aligned Nanotubes Grown on a-Plane SapphireAligned Nanotubes Grown on a-Plane Sapphire
Zhou et al JACS 127 5294 (2005)
Zhou Zhou et alet al Nano Letters Nano Letters (2006)(2006)(Top ten hot articles in 2006)
High density SWNTsUp to 40 nanotubes μmInter-nanotube spacing ~ 25 nm
Low density SWNTs
Control of Nanotube DensityControl of Nanotube Density
Zhou et al JACS 127 5294 (2005) Zhou Zhou et alet al Nano Letters (2006) Nano Letters (2006)
a-plane
Red spheres oxygen atomsBlue spheres aluminum atomsPurple plane a-plane orientation
Hypothetic Schematic Diagram of SWNT on a-Plane SapphireHypothetic Schematic Diagram of SWNT on a-Plane Sapphire
Calculation of Lennard-Jones Potential Calculation of Lennard-Jones Potential
sumsum⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
minusminus⎟
⎟
⎠
⎞
⎜⎜
⎝
⎛
minus+
⎥⎥
⎦
⎤
⎢⎢
⎣
⎡
⎟⎟⎠
⎞⎜⎜⎝
⎛
minusminus⎟
⎟⎠
⎞⎜⎜⎝
⎛
minus=
j j
CAl
j
CAlCAl
i i
CO
i
COCO rrrrrrrr
rU
612612
44)( vvvvvvvvv σσ
εσσ
ε
a carbon atom and oxygen atoms in sapphire
a carbon atom and oxygen atoms in sapphire
a carbon atom and Al atoms in sapphire
a carbon atom and Al atoms in sapphire
Interaction between
Interaction between
C-plane C-plane a-plane a-plane
Potential wellPotential wellZhou Zhou et alet al JPCC JPCC 112 15929 (200(20088))
Synthesis of Nanotubes with Controlled Orientations and Positions
Synthesis of Nanotubes with Controlled Orientations and Positions
Catalyst
Photo Resist
QuartzSapphire
Catalyst Island
Aligned NanotubesMetal Electrode
SD
G
Dielectric Layer
3-10 nanotubes microm
Aligned Nanotubes on Quartz Using Patterned CatalystAligned Nanotubes on Quartz Using Patterned Catalystcatalyst
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
(a)
Poly Si Gate
Gate Oxide
SourceDrain Electrode
(b)
NanotubeGate Dielectric
Gate
SourceDrain Electrode
Comparison between Silicon-on-insulator (SOI) and Nanotube-on-Insulator (NOI)
Comparison between SiliconComparison between Silicon--onon--insulator (SOI) and insulator (SOI) and NanotubeNanotube--onon--Insulator (NOI)Insulator (NOI)
SOISOISOI NOINOINOI
Common Features1 Active material (Si or SWNT) is all over the surface2 Many devices can be patterned anywhere on the substrate3 Unwanted silicon or SWNTs can be removed via etching4 SOI and NOI offer minimized parasitic capacitance faster switching speed
and lower dynamic power consumption
Common FeaturesCommon Features11 Active material (Si or SWNT) is all over the surfaceActive material (Si or SWNT) is all over the surface22 Many devices can be patterned anywhere on the substrateMany devices can be patterned anywhere on the substrate33 Unwanted silicon or Unwanted silicon or SWNTsSWNTs can be removed via etchingcan be removed via etching44 SOI and NOI offer minimized parasitic capacitance faster switchSOI and NOI offer minimized parasitic capacitance faster switching speed ing speed
and lower dynamic power consumptionand lower dynamic power consumption Zhou et al Nano Letters (2006)
a-Sapphire
Wafer-Scale Aligned Nanotube SynthesisWafer-Scale Aligned Nanotube Synthesis
1200
1000
800
600
400
200
Tem
pera
ture
200150100500
Time (min)
Growth Annealing
Key meticulous temperature control amp uniform growth
1μm
Quartz 1000
800
600
400
200Tem
pera
ture
6004002000
Time (min)
Growth Annealing
1μm
4 inch substrate
Gas in
Gas out
Quartz or Sapphire with patterned
catalyst
9 feet-long growth furnace with three-zone
Wafer-Scale CNT TransferWafer-Scale CNT TransferTransfer fullTransfer full--wafer of wafer of CNTsCNTs from quartz growth substrate to SiOfrom quartz growth substrate to SiO22Si fabrication Si fabrication
substrate substrate allows largeallows large--scale integrationscale integration
Nano Lett 9 189ndash197 20094
Wafer-Scale Aligned Nanotube Device FabricationWafer-Scale Aligned Nanotube Device Fabrication
Back-Gated Submicron TransistorsBack-Gated Submicron Transistors
Back-gated transistors
1 microm
L = 1 microm
1 microm
L = 075 microm
1 microm
L = 05 microm
I-Vg curves Channel length dependence
-120
-100
-80
-60
-40
-20
0
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
-60
-40
-20
0
I ds (μ
Α)
-1500Vds (V)
-1 V
-08 V
-06 V
-04 V
-02 V
Vg from -8V to 8V
15
10
05
I ds (m
A)
-10 -5 0 5 10Vg (V)
L = 05 microm L = 075 microm L = 1 microm L = 2 microm L = 5 microm L = 10 microm L = 20 microm
80
60
40
20
gm
(μ S
)
5 6 7 81
2 3 4 5 6 7 810
2
L(μm)
2
4
6810-6
2
4
6810-5
I DW
(mA
microm
) gm
Ion Ioff
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Aligned Nanotubes for Devices and Circuits Aligned Nanotubes for Devices and Circuits
-- Project Mission Project Mission We want to tackle the challenging issue of We want to tackle the challenging issue of nanotube nanotube assembly and integrationassembly and integration
We want to grow carbon nanotubes withWe want to grow carbon nanotubes withControlled orientation (achieved by using Controlled orientation (achieved by using sapphire and quartz) sapphire and quartz) Controlled position (achieved) Controlled position (achieved) Controlled density (achieved) Controlled density (achieved) Controlled diameter (ongoing)Controlled diameter (ongoing)Controlled Controlled chiralitychirality (ongoing)(ongoing)
-- Our Approach Our Approach A novel nanotubeA novel nanotube--onon--insulator (NOI) insulator (NOI) approach based on approach based on aligned nanotubesaligned nanotubes for for integrated nanotube circuitsintegrated nanotube circuits Nanotube
devicesNanotube
circuits
Quartz SubstrateCatalyst Particle
Quartz Substrate
Nanotube
One of the first to grow aligned nanotubes on sapphireOne of the first to grow aligned nanotubes on sapphireJ of Am Chem Soc 127 5294 J of Am Chem Soc 127 5294 -- 5295 (2005) 5295 (2005)
The first to make aligned nanotube transistorsThe first to make aligned nanotube transistorsNano Letters 6 34Nano Letters 6 34--39 (2006)39 (2006)Reported by Reported by Scientific AmericanScientific American (April 2006 P16) (April 2006 P16)
The first to demonstrate waferThe first to demonstrate wafer--scale processing of aligned scale processing of aligned nanotube devices and circuitsnanotube devices and circuits
Logic circuits (CMOS inverter NAND NOR)Logic circuits (CMOS inverter NAND NOR)
The first to make transparent nanotube devicesThe first to make transparent nanotube devicesACS Nano in press (2008)ACS Nano in press (2008)
Chip
1
2
3
4
5
Our Achievements on Aligned Single-Walled NanotubesOur Achievements on Aligned SingleOur Achievements on Aligned Single--Walled NanotubesWalled Nanotubes
Synthesis of Aligned Nanotubes on Sapphire QuartzSynthesis of Aligned Nanotubes on Sapphire Quartz
Gas in
Gas out
Sapphire with catalyst
Substrate Sapphire quartzCatalyst FerritinTemperature 900degCGas flow rate
CH4 2000 sccmC2H4 10 sccmH2 800 sccm
Generation IIFull Wafer Production
Generation IIFull Wafer Production
50 μm
2 0
1 5
1 0
5N
umbe
r
2 01 0D iam e te r (nm)500 nm
134 plusmn 030 nm
1 All nanotubes grow normal to the c axis on a-plane sapphire2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin11 All nanotubes grow normal to the c axis on aAll nanotubes grow normal to the c axis on a--plane sapphireplane sapphire2 Narrow diameter distribution of 2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin
c axis
Aligned Nanotubes Grown on a-Plane SapphireAligned Nanotubes Grown on a-Plane Sapphire
Zhou et al JACS 127 5294 (2005)
Zhou Zhou et alet al Nano Letters Nano Letters (2006)(2006)(Top ten hot articles in 2006)
High density SWNTsUp to 40 nanotubes μmInter-nanotube spacing ~ 25 nm
Low density SWNTs
Control of Nanotube DensityControl of Nanotube Density
Zhou et al JACS 127 5294 (2005) Zhou Zhou et alet al Nano Letters (2006) Nano Letters (2006)
a-plane
Red spheres oxygen atomsBlue spheres aluminum atomsPurple plane a-plane orientation
Hypothetic Schematic Diagram of SWNT on a-Plane SapphireHypothetic Schematic Diagram of SWNT on a-Plane Sapphire
Calculation of Lennard-Jones Potential Calculation of Lennard-Jones Potential
sumsum⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
minusminus⎟
⎟
⎠
⎞
⎜⎜
⎝
⎛
minus+
⎥⎥
⎦
⎤
⎢⎢
⎣
⎡
⎟⎟⎠
⎞⎜⎜⎝
⎛
minusminus⎟
⎟⎠
⎞⎜⎜⎝
⎛
minus=
j j
CAl
j
CAlCAl
i i
CO
i
COCO rrrrrrrr
rU
612612
44)( vvvvvvvvv σσ
εσσ
ε
a carbon atom and oxygen atoms in sapphire
a carbon atom and oxygen atoms in sapphire
a carbon atom and Al atoms in sapphire
a carbon atom and Al atoms in sapphire
Interaction between
Interaction between
C-plane C-plane a-plane a-plane
Potential wellPotential wellZhou Zhou et alet al JPCC JPCC 112 15929 (200(20088))
Synthesis of Nanotubes with Controlled Orientations and Positions
Synthesis of Nanotubes with Controlled Orientations and Positions
Catalyst
Photo Resist
QuartzSapphire
Catalyst Island
Aligned NanotubesMetal Electrode
SD
G
Dielectric Layer
3-10 nanotubes microm
Aligned Nanotubes on Quartz Using Patterned CatalystAligned Nanotubes on Quartz Using Patterned Catalystcatalyst
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
(a)
Poly Si Gate
Gate Oxide
SourceDrain Electrode
(b)
NanotubeGate Dielectric
Gate
SourceDrain Electrode
Comparison between Silicon-on-insulator (SOI) and Nanotube-on-Insulator (NOI)
Comparison between SiliconComparison between Silicon--onon--insulator (SOI) and insulator (SOI) and NanotubeNanotube--onon--Insulator (NOI)Insulator (NOI)
SOISOISOI NOINOINOI
Common Features1 Active material (Si or SWNT) is all over the surface2 Many devices can be patterned anywhere on the substrate3 Unwanted silicon or SWNTs can be removed via etching4 SOI and NOI offer minimized parasitic capacitance faster switching speed
and lower dynamic power consumption
Common FeaturesCommon Features11 Active material (Si or SWNT) is all over the surfaceActive material (Si or SWNT) is all over the surface22 Many devices can be patterned anywhere on the substrateMany devices can be patterned anywhere on the substrate33 Unwanted silicon or Unwanted silicon or SWNTsSWNTs can be removed via etchingcan be removed via etching44 SOI and NOI offer minimized parasitic capacitance faster switchSOI and NOI offer minimized parasitic capacitance faster switching speed ing speed
and lower dynamic power consumptionand lower dynamic power consumption Zhou et al Nano Letters (2006)
a-Sapphire
Wafer-Scale Aligned Nanotube SynthesisWafer-Scale Aligned Nanotube Synthesis
1200
1000
800
600
400
200
Tem
pera
ture
200150100500
Time (min)
Growth Annealing
Key meticulous temperature control amp uniform growth
1μm
Quartz 1000
800
600
400
200Tem
pera
ture
6004002000
Time (min)
Growth Annealing
1μm
4 inch substrate
Gas in
Gas out
Quartz or Sapphire with patterned
catalyst
9 feet-long growth furnace with three-zone
Wafer-Scale CNT TransferWafer-Scale CNT TransferTransfer fullTransfer full--wafer of wafer of CNTsCNTs from quartz growth substrate to SiOfrom quartz growth substrate to SiO22Si fabrication Si fabrication
substrate substrate allows largeallows large--scale integrationscale integration
Nano Lett 9 189ndash197 20094
Wafer-Scale Aligned Nanotube Device FabricationWafer-Scale Aligned Nanotube Device Fabrication
Back-Gated Submicron TransistorsBack-Gated Submicron Transistors
Back-gated transistors
1 microm
L = 1 microm
1 microm
L = 075 microm
1 microm
L = 05 microm
I-Vg curves Channel length dependence
-120
-100
-80
-60
-40
-20
0
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
-60
-40
-20
0
I ds (μ
Α)
-1500Vds (V)
-1 V
-08 V
-06 V
-04 V
-02 V
Vg from -8V to 8V
15
10
05
I ds (m
A)
-10 -5 0 5 10Vg (V)
L = 05 microm L = 075 microm L = 1 microm L = 2 microm L = 5 microm L = 10 microm L = 20 microm
80
60
40
20
gm
(μ S
)
5 6 7 81
2 3 4 5 6 7 810
2
L(μm)
2
4
6810-6
2
4
6810-5
I DW
(mA
microm
) gm
Ion Ioff
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
One of the first to grow aligned nanotubes on sapphireOne of the first to grow aligned nanotubes on sapphireJ of Am Chem Soc 127 5294 J of Am Chem Soc 127 5294 -- 5295 (2005) 5295 (2005)
The first to make aligned nanotube transistorsThe first to make aligned nanotube transistorsNano Letters 6 34Nano Letters 6 34--39 (2006)39 (2006)Reported by Reported by Scientific AmericanScientific American (April 2006 P16) (April 2006 P16)
The first to demonstrate waferThe first to demonstrate wafer--scale processing of aligned scale processing of aligned nanotube devices and circuitsnanotube devices and circuits
Logic circuits (CMOS inverter NAND NOR)Logic circuits (CMOS inverter NAND NOR)
The first to make transparent nanotube devicesThe first to make transparent nanotube devicesACS Nano in press (2008)ACS Nano in press (2008)
Chip
1
2
3
4
5
Our Achievements on Aligned Single-Walled NanotubesOur Achievements on Aligned SingleOur Achievements on Aligned Single--Walled NanotubesWalled Nanotubes
Synthesis of Aligned Nanotubes on Sapphire QuartzSynthesis of Aligned Nanotubes on Sapphire Quartz
Gas in
Gas out
Sapphire with catalyst
Substrate Sapphire quartzCatalyst FerritinTemperature 900degCGas flow rate
CH4 2000 sccmC2H4 10 sccmH2 800 sccm
Generation IIFull Wafer Production
Generation IIFull Wafer Production
50 μm
2 0
1 5
1 0
5N
umbe
r
2 01 0D iam e te r (nm)500 nm
134 plusmn 030 nm
1 All nanotubes grow normal to the c axis on a-plane sapphire2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin11 All nanotubes grow normal to the c axis on aAll nanotubes grow normal to the c axis on a--plane sapphireplane sapphire2 Narrow diameter distribution of 2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin
c axis
Aligned Nanotubes Grown on a-Plane SapphireAligned Nanotubes Grown on a-Plane Sapphire
Zhou et al JACS 127 5294 (2005)
Zhou Zhou et alet al Nano Letters Nano Letters (2006)(2006)(Top ten hot articles in 2006)
High density SWNTsUp to 40 nanotubes μmInter-nanotube spacing ~ 25 nm
Low density SWNTs
Control of Nanotube DensityControl of Nanotube Density
Zhou et al JACS 127 5294 (2005) Zhou Zhou et alet al Nano Letters (2006) Nano Letters (2006)
a-plane
Red spheres oxygen atomsBlue spheres aluminum atomsPurple plane a-plane orientation
Hypothetic Schematic Diagram of SWNT on a-Plane SapphireHypothetic Schematic Diagram of SWNT on a-Plane Sapphire
Calculation of Lennard-Jones Potential Calculation of Lennard-Jones Potential
sumsum⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
minusminus⎟
⎟
⎠
⎞
⎜⎜
⎝
⎛
minus+
⎥⎥
⎦
⎤
⎢⎢
⎣
⎡
⎟⎟⎠
⎞⎜⎜⎝
⎛
minusminus⎟
⎟⎠
⎞⎜⎜⎝
⎛
minus=
j j
CAl
j
CAlCAl
i i
CO
i
COCO rrrrrrrr
rU
612612
44)( vvvvvvvvv σσ
εσσ
ε
a carbon atom and oxygen atoms in sapphire
a carbon atom and oxygen atoms in sapphire
a carbon atom and Al atoms in sapphire
a carbon atom and Al atoms in sapphire
Interaction between
Interaction between
C-plane C-plane a-plane a-plane
Potential wellPotential wellZhou Zhou et alet al JPCC JPCC 112 15929 (200(20088))
Synthesis of Nanotubes with Controlled Orientations and Positions
Synthesis of Nanotubes with Controlled Orientations and Positions
Catalyst
Photo Resist
QuartzSapphire
Catalyst Island
Aligned NanotubesMetal Electrode
SD
G
Dielectric Layer
3-10 nanotubes microm
Aligned Nanotubes on Quartz Using Patterned CatalystAligned Nanotubes on Quartz Using Patterned Catalystcatalyst
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
(a)
Poly Si Gate
Gate Oxide
SourceDrain Electrode
(b)
NanotubeGate Dielectric
Gate
SourceDrain Electrode
Comparison between Silicon-on-insulator (SOI) and Nanotube-on-Insulator (NOI)
Comparison between SiliconComparison between Silicon--onon--insulator (SOI) and insulator (SOI) and NanotubeNanotube--onon--Insulator (NOI)Insulator (NOI)
SOISOISOI NOINOINOI
Common Features1 Active material (Si or SWNT) is all over the surface2 Many devices can be patterned anywhere on the substrate3 Unwanted silicon or SWNTs can be removed via etching4 SOI and NOI offer minimized parasitic capacitance faster switching speed
and lower dynamic power consumption
Common FeaturesCommon Features11 Active material (Si or SWNT) is all over the surfaceActive material (Si or SWNT) is all over the surface22 Many devices can be patterned anywhere on the substrateMany devices can be patterned anywhere on the substrate33 Unwanted silicon or Unwanted silicon or SWNTsSWNTs can be removed via etchingcan be removed via etching44 SOI and NOI offer minimized parasitic capacitance faster switchSOI and NOI offer minimized parasitic capacitance faster switching speed ing speed
and lower dynamic power consumptionand lower dynamic power consumption Zhou et al Nano Letters (2006)
a-Sapphire
Wafer-Scale Aligned Nanotube SynthesisWafer-Scale Aligned Nanotube Synthesis
1200
1000
800
600
400
200
Tem
pera
ture
200150100500
Time (min)
Growth Annealing
Key meticulous temperature control amp uniform growth
1μm
Quartz 1000
800
600
400
200Tem
pera
ture
6004002000
Time (min)
Growth Annealing
1μm
4 inch substrate
Gas in
Gas out
Quartz or Sapphire with patterned
catalyst
9 feet-long growth furnace with three-zone
Wafer-Scale CNT TransferWafer-Scale CNT TransferTransfer fullTransfer full--wafer of wafer of CNTsCNTs from quartz growth substrate to SiOfrom quartz growth substrate to SiO22Si fabrication Si fabrication
substrate substrate allows largeallows large--scale integrationscale integration
Nano Lett 9 189ndash197 20094
Wafer-Scale Aligned Nanotube Device FabricationWafer-Scale Aligned Nanotube Device Fabrication
Back-Gated Submicron TransistorsBack-Gated Submicron Transistors
Back-gated transistors
1 microm
L = 1 microm
1 microm
L = 075 microm
1 microm
L = 05 microm
I-Vg curves Channel length dependence
-120
-100
-80
-60
-40
-20
0
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
-60
-40
-20
0
I ds (μ
Α)
-1500Vds (V)
-1 V
-08 V
-06 V
-04 V
-02 V
Vg from -8V to 8V
15
10
05
I ds (m
A)
-10 -5 0 5 10Vg (V)
L = 05 microm L = 075 microm L = 1 microm L = 2 microm L = 5 microm L = 10 microm L = 20 microm
80
60
40
20
gm
(μ S
)
5 6 7 81
2 3 4 5 6 7 810
2
L(μm)
2
4
6810-6
2
4
6810-5
I DW
(mA
microm
) gm
Ion Ioff
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Synthesis of Aligned Nanotubes on Sapphire QuartzSynthesis of Aligned Nanotubes on Sapphire Quartz
Gas in
Gas out
Sapphire with catalyst
Substrate Sapphire quartzCatalyst FerritinTemperature 900degCGas flow rate
CH4 2000 sccmC2H4 10 sccmH2 800 sccm
Generation IIFull Wafer Production
Generation IIFull Wafer Production
50 μm
2 0
1 5
1 0
5N
umbe
r
2 01 0D iam e te r (nm)500 nm
134 plusmn 030 nm
1 All nanotubes grow normal to the c axis on a-plane sapphire2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin11 All nanotubes grow normal to the c axis on aAll nanotubes grow normal to the c axis on a--plane sapphireplane sapphire2 Narrow diameter distribution of 2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin
c axis
Aligned Nanotubes Grown on a-Plane SapphireAligned Nanotubes Grown on a-Plane Sapphire
Zhou et al JACS 127 5294 (2005)
Zhou Zhou et alet al Nano Letters Nano Letters (2006)(2006)(Top ten hot articles in 2006)
High density SWNTsUp to 40 nanotubes μmInter-nanotube spacing ~ 25 nm
Low density SWNTs
Control of Nanotube DensityControl of Nanotube Density
Zhou et al JACS 127 5294 (2005) Zhou Zhou et alet al Nano Letters (2006) Nano Letters (2006)
a-plane
Red spheres oxygen atomsBlue spheres aluminum atomsPurple plane a-plane orientation
Hypothetic Schematic Diagram of SWNT on a-Plane SapphireHypothetic Schematic Diagram of SWNT on a-Plane Sapphire
Calculation of Lennard-Jones Potential Calculation of Lennard-Jones Potential
sumsum⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
minusminus⎟
⎟
⎠
⎞
⎜⎜
⎝
⎛
minus+
⎥⎥
⎦
⎤
⎢⎢
⎣
⎡
⎟⎟⎠
⎞⎜⎜⎝
⎛
minusminus⎟
⎟⎠
⎞⎜⎜⎝
⎛
minus=
j j
CAl
j
CAlCAl
i i
CO
i
COCO rrrrrrrr
rU
612612
44)( vvvvvvvvv σσ
εσσ
ε
a carbon atom and oxygen atoms in sapphire
a carbon atom and oxygen atoms in sapphire
a carbon atom and Al atoms in sapphire
a carbon atom and Al atoms in sapphire
Interaction between
Interaction between
C-plane C-plane a-plane a-plane
Potential wellPotential wellZhou Zhou et alet al JPCC JPCC 112 15929 (200(20088))
Synthesis of Nanotubes with Controlled Orientations and Positions
Synthesis of Nanotubes with Controlled Orientations and Positions
Catalyst
Photo Resist
QuartzSapphire
Catalyst Island
Aligned NanotubesMetal Electrode
SD
G
Dielectric Layer
3-10 nanotubes microm
Aligned Nanotubes on Quartz Using Patterned CatalystAligned Nanotubes on Quartz Using Patterned Catalystcatalyst
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
(a)
Poly Si Gate
Gate Oxide
SourceDrain Electrode
(b)
NanotubeGate Dielectric
Gate
SourceDrain Electrode
Comparison between Silicon-on-insulator (SOI) and Nanotube-on-Insulator (NOI)
Comparison between SiliconComparison between Silicon--onon--insulator (SOI) and insulator (SOI) and NanotubeNanotube--onon--Insulator (NOI)Insulator (NOI)
SOISOISOI NOINOINOI
Common Features1 Active material (Si or SWNT) is all over the surface2 Many devices can be patterned anywhere on the substrate3 Unwanted silicon or SWNTs can be removed via etching4 SOI and NOI offer minimized parasitic capacitance faster switching speed
and lower dynamic power consumption
Common FeaturesCommon Features11 Active material (Si or SWNT) is all over the surfaceActive material (Si or SWNT) is all over the surface22 Many devices can be patterned anywhere on the substrateMany devices can be patterned anywhere on the substrate33 Unwanted silicon or Unwanted silicon or SWNTsSWNTs can be removed via etchingcan be removed via etching44 SOI and NOI offer minimized parasitic capacitance faster switchSOI and NOI offer minimized parasitic capacitance faster switching speed ing speed
and lower dynamic power consumptionand lower dynamic power consumption Zhou et al Nano Letters (2006)
a-Sapphire
Wafer-Scale Aligned Nanotube SynthesisWafer-Scale Aligned Nanotube Synthesis
1200
1000
800
600
400
200
Tem
pera
ture
200150100500
Time (min)
Growth Annealing
Key meticulous temperature control amp uniform growth
1μm
Quartz 1000
800
600
400
200Tem
pera
ture
6004002000
Time (min)
Growth Annealing
1μm
4 inch substrate
Gas in
Gas out
Quartz or Sapphire with patterned
catalyst
9 feet-long growth furnace with three-zone
Wafer-Scale CNT TransferWafer-Scale CNT TransferTransfer fullTransfer full--wafer of wafer of CNTsCNTs from quartz growth substrate to SiOfrom quartz growth substrate to SiO22Si fabrication Si fabrication
substrate substrate allows largeallows large--scale integrationscale integration
Nano Lett 9 189ndash197 20094
Wafer-Scale Aligned Nanotube Device FabricationWafer-Scale Aligned Nanotube Device Fabrication
Back-Gated Submicron TransistorsBack-Gated Submicron Transistors
Back-gated transistors
1 microm
L = 1 microm
1 microm
L = 075 microm
1 microm
L = 05 microm
I-Vg curves Channel length dependence
-120
-100
-80
-60
-40
-20
0
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
-60
-40
-20
0
I ds (μ
Α)
-1500Vds (V)
-1 V
-08 V
-06 V
-04 V
-02 V
Vg from -8V to 8V
15
10
05
I ds (m
A)
-10 -5 0 5 10Vg (V)
L = 05 microm L = 075 microm L = 1 microm L = 2 microm L = 5 microm L = 10 microm L = 20 microm
80
60
40
20
gm
(μ S
)
5 6 7 81
2 3 4 5 6 7 810
2
L(μm)
2
4
6810-6
2
4
6810-5
I DW
(mA
microm
) gm
Ion Ioff
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
50 μm
2 0
1 5
1 0
5N
umbe
r
2 01 0D iam e te r (nm)500 nm
134 plusmn 030 nm
1 All nanotubes grow normal to the c axis on a-plane sapphire2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin11 All nanotubes grow normal to the c axis on aAll nanotubes grow normal to the c axis on a--plane sapphireplane sapphire2 Narrow diameter distribution of 2 Narrow diameter distribution of 134 plusmn 030 nm obtained with commercial ferrtin
c axis
Aligned Nanotubes Grown on a-Plane SapphireAligned Nanotubes Grown on a-Plane Sapphire
Zhou et al JACS 127 5294 (2005)
Zhou Zhou et alet al Nano Letters Nano Letters (2006)(2006)(Top ten hot articles in 2006)
High density SWNTsUp to 40 nanotubes μmInter-nanotube spacing ~ 25 nm
Low density SWNTs
Control of Nanotube DensityControl of Nanotube Density
Zhou et al JACS 127 5294 (2005) Zhou Zhou et alet al Nano Letters (2006) Nano Letters (2006)
a-plane
Red spheres oxygen atomsBlue spheres aluminum atomsPurple plane a-plane orientation
Hypothetic Schematic Diagram of SWNT on a-Plane SapphireHypothetic Schematic Diagram of SWNT on a-Plane Sapphire
Calculation of Lennard-Jones Potential Calculation of Lennard-Jones Potential
sumsum⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
minusminus⎟
⎟
⎠
⎞
⎜⎜
⎝
⎛
minus+
⎥⎥
⎦
⎤
⎢⎢
⎣
⎡
⎟⎟⎠
⎞⎜⎜⎝
⎛
minusminus⎟
⎟⎠
⎞⎜⎜⎝
⎛
minus=
j j
CAl
j
CAlCAl
i i
CO
i
COCO rrrrrrrr
rU
612612
44)( vvvvvvvvv σσ
εσσ
ε
a carbon atom and oxygen atoms in sapphire
a carbon atom and oxygen atoms in sapphire
a carbon atom and Al atoms in sapphire
a carbon atom and Al atoms in sapphire
Interaction between
Interaction between
C-plane C-plane a-plane a-plane
Potential wellPotential wellZhou Zhou et alet al JPCC JPCC 112 15929 (200(20088))
Synthesis of Nanotubes with Controlled Orientations and Positions
Synthesis of Nanotubes with Controlled Orientations and Positions
Catalyst
Photo Resist
QuartzSapphire
Catalyst Island
Aligned NanotubesMetal Electrode
SD
G
Dielectric Layer
3-10 nanotubes microm
Aligned Nanotubes on Quartz Using Patterned CatalystAligned Nanotubes on Quartz Using Patterned Catalystcatalyst
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
(a)
Poly Si Gate
Gate Oxide
SourceDrain Electrode
(b)
NanotubeGate Dielectric
Gate
SourceDrain Electrode
Comparison between Silicon-on-insulator (SOI) and Nanotube-on-Insulator (NOI)
Comparison between SiliconComparison between Silicon--onon--insulator (SOI) and insulator (SOI) and NanotubeNanotube--onon--Insulator (NOI)Insulator (NOI)
SOISOISOI NOINOINOI
Common Features1 Active material (Si or SWNT) is all over the surface2 Many devices can be patterned anywhere on the substrate3 Unwanted silicon or SWNTs can be removed via etching4 SOI and NOI offer minimized parasitic capacitance faster switching speed
and lower dynamic power consumption
Common FeaturesCommon Features11 Active material (Si or SWNT) is all over the surfaceActive material (Si or SWNT) is all over the surface22 Many devices can be patterned anywhere on the substrateMany devices can be patterned anywhere on the substrate33 Unwanted silicon or Unwanted silicon or SWNTsSWNTs can be removed via etchingcan be removed via etching44 SOI and NOI offer minimized parasitic capacitance faster switchSOI and NOI offer minimized parasitic capacitance faster switching speed ing speed
and lower dynamic power consumptionand lower dynamic power consumption Zhou et al Nano Letters (2006)
a-Sapphire
Wafer-Scale Aligned Nanotube SynthesisWafer-Scale Aligned Nanotube Synthesis
1200
1000
800
600
400
200
Tem
pera
ture
200150100500
Time (min)
Growth Annealing
Key meticulous temperature control amp uniform growth
1μm
Quartz 1000
800
600
400
200Tem
pera
ture
6004002000
Time (min)
Growth Annealing
1μm
4 inch substrate
Gas in
Gas out
Quartz or Sapphire with patterned
catalyst
9 feet-long growth furnace with three-zone
Wafer-Scale CNT TransferWafer-Scale CNT TransferTransfer fullTransfer full--wafer of wafer of CNTsCNTs from quartz growth substrate to SiOfrom quartz growth substrate to SiO22Si fabrication Si fabrication
substrate substrate allows largeallows large--scale integrationscale integration
Nano Lett 9 189ndash197 20094
Wafer-Scale Aligned Nanotube Device FabricationWafer-Scale Aligned Nanotube Device Fabrication
Back-Gated Submicron TransistorsBack-Gated Submicron Transistors
Back-gated transistors
1 microm
L = 1 microm
1 microm
L = 075 microm
1 microm
L = 05 microm
I-Vg curves Channel length dependence
-120
-100
-80
-60
-40
-20
0
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
-60
-40
-20
0
I ds (μ
Α)
-1500Vds (V)
-1 V
-08 V
-06 V
-04 V
-02 V
Vg from -8V to 8V
15
10
05
I ds (m
A)
-10 -5 0 5 10Vg (V)
L = 05 microm L = 075 microm L = 1 microm L = 2 microm L = 5 microm L = 10 microm L = 20 microm
80
60
40
20
gm
(μ S
)
5 6 7 81
2 3 4 5 6 7 810
2
L(μm)
2
4
6810-6
2
4
6810-5
I DW
(mA
microm
) gm
Ion Ioff
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
High density SWNTsUp to 40 nanotubes μmInter-nanotube spacing ~ 25 nm
Low density SWNTs
Control of Nanotube DensityControl of Nanotube Density
Zhou et al JACS 127 5294 (2005) Zhou Zhou et alet al Nano Letters (2006) Nano Letters (2006)
a-plane
Red spheres oxygen atomsBlue spheres aluminum atomsPurple plane a-plane orientation
Hypothetic Schematic Diagram of SWNT on a-Plane SapphireHypothetic Schematic Diagram of SWNT on a-Plane Sapphire
Calculation of Lennard-Jones Potential Calculation of Lennard-Jones Potential
sumsum⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
minusminus⎟
⎟
⎠
⎞
⎜⎜
⎝
⎛
minus+
⎥⎥
⎦
⎤
⎢⎢
⎣
⎡
⎟⎟⎠
⎞⎜⎜⎝
⎛
minusminus⎟
⎟⎠
⎞⎜⎜⎝
⎛
minus=
j j
CAl
j
CAlCAl
i i
CO
i
COCO rrrrrrrr
rU
612612
44)( vvvvvvvvv σσ
εσσ
ε
a carbon atom and oxygen atoms in sapphire
a carbon atom and oxygen atoms in sapphire
a carbon atom and Al atoms in sapphire
a carbon atom and Al atoms in sapphire
Interaction between
Interaction between
C-plane C-plane a-plane a-plane
Potential wellPotential wellZhou Zhou et alet al JPCC JPCC 112 15929 (200(20088))
Synthesis of Nanotubes with Controlled Orientations and Positions
Synthesis of Nanotubes with Controlled Orientations and Positions
Catalyst
Photo Resist
QuartzSapphire
Catalyst Island
Aligned NanotubesMetal Electrode
SD
G
Dielectric Layer
3-10 nanotubes microm
Aligned Nanotubes on Quartz Using Patterned CatalystAligned Nanotubes on Quartz Using Patterned Catalystcatalyst
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
(a)
Poly Si Gate
Gate Oxide
SourceDrain Electrode
(b)
NanotubeGate Dielectric
Gate
SourceDrain Electrode
Comparison between Silicon-on-insulator (SOI) and Nanotube-on-Insulator (NOI)
Comparison between SiliconComparison between Silicon--onon--insulator (SOI) and insulator (SOI) and NanotubeNanotube--onon--Insulator (NOI)Insulator (NOI)
SOISOISOI NOINOINOI
Common Features1 Active material (Si or SWNT) is all over the surface2 Many devices can be patterned anywhere on the substrate3 Unwanted silicon or SWNTs can be removed via etching4 SOI and NOI offer minimized parasitic capacitance faster switching speed
and lower dynamic power consumption
Common FeaturesCommon Features11 Active material (Si or SWNT) is all over the surfaceActive material (Si or SWNT) is all over the surface22 Many devices can be patterned anywhere on the substrateMany devices can be patterned anywhere on the substrate33 Unwanted silicon or Unwanted silicon or SWNTsSWNTs can be removed via etchingcan be removed via etching44 SOI and NOI offer minimized parasitic capacitance faster switchSOI and NOI offer minimized parasitic capacitance faster switching speed ing speed
and lower dynamic power consumptionand lower dynamic power consumption Zhou et al Nano Letters (2006)
a-Sapphire
Wafer-Scale Aligned Nanotube SynthesisWafer-Scale Aligned Nanotube Synthesis
1200
1000
800
600
400
200
Tem
pera
ture
200150100500
Time (min)
Growth Annealing
Key meticulous temperature control amp uniform growth
1μm
Quartz 1000
800
600
400
200Tem
pera
ture
6004002000
Time (min)
Growth Annealing
1μm
4 inch substrate
Gas in
Gas out
Quartz or Sapphire with patterned
catalyst
9 feet-long growth furnace with three-zone
Wafer-Scale CNT TransferWafer-Scale CNT TransferTransfer fullTransfer full--wafer of wafer of CNTsCNTs from quartz growth substrate to SiOfrom quartz growth substrate to SiO22Si fabrication Si fabrication
substrate substrate allows largeallows large--scale integrationscale integration
Nano Lett 9 189ndash197 20094
Wafer-Scale Aligned Nanotube Device FabricationWafer-Scale Aligned Nanotube Device Fabrication
Back-Gated Submicron TransistorsBack-Gated Submicron Transistors
Back-gated transistors
1 microm
L = 1 microm
1 microm
L = 075 microm
1 microm
L = 05 microm
I-Vg curves Channel length dependence
-120
-100
-80
-60
-40
-20
0
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
-60
-40
-20
0
I ds (μ
Α)
-1500Vds (V)
-1 V
-08 V
-06 V
-04 V
-02 V
Vg from -8V to 8V
15
10
05
I ds (m
A)
-10 -5 0 5 10Vg (V)
L = 05 microm L = 075 microm L = 1 microm L = 2 microm L = 5 microm L = 10 microm L = 20 microm
80
60
40
20
gm
(μ S
)
5 6 7 81
2 3 4 5 6 7 810
2
L(μm)
2
4
6810-6
2
4
6810-5
I DW
(mA
microm
) gm
Ion Ioff
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
a-plane
Red spheres oxygen atomsBlue spheres aluminum atomsPurple plane a-plane orientation
Hypothetic Schematic Diagram of SWNT on a-Plane SapphireHypothetic Schematic Diagram of SWNT on a-Plane Sapphire
Calculation of Lennard-Jones Potential Calculation of Lennard-Jones Potential
sumsum⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
minusminus⎟
⎟
⎠
⎞
⎜⎜
⎝
⎛
minus+
⎥⎥
⎦
⎤
⎢⎢
⎣
⎡
⎟⎟⎠
⎞⎜⎜⎝
⎛
minusminus⎟
⎟⎠
⎞⎜⎜⎝
⎛
minus=
j j
CAl
j
CAlCAl
i i
CO
i
COCO rrrrrrrr
rU
612612
44)( vvvvvvvvv σσ
εσσ
ε
a carbon atom and oxygen atoms in sapphire
a carbon atom and oxygen atoms in sapphire
a carbon atom and Al atoms in sapphire
a carbon atom and Al atoms in sapphire
Interaction between
Interaction between
C-plane C-plane a-plane a-plane
Potential wellPotential wellZhou Zhou et alet al JPCC JPCC 112 15929 (200(20088))
Synthesis of Nanotubes with Controlled Orientations and Positions
Synthesis of Nanotubes with Controlled Orientations and Positions
Catalyst
Photo Resist
QuartzSapphire
Catalyst Island
Aligned NanotubesMetal Electrode
SD
G
Dielectric Layer
3-10 nanotubes microm
Aligned Nanotubes on Quartz Using Patterned CatalystAligned Nanotubes on Quartz Using Patterned Catalystcatalyst
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
(a)
Poly Si Gate
Gate Oxide
SourceDrain Electrode
(b)
NanotubeGate Dielectric
Gate
SourceDrain Electrode
Comparison between Silicon-on-insulator (SOI) and Nanotube-on-Insulator (NOI)
Comparison between SiliconComparison between Silicon--onon--insulator (SOI) and insulator (SOI) and NanotubeNanotube--onon--Insulator (NOI)Insulator (NOI)
SOISOISOI NOINOINOI
Common Features1 Active material (Si or SWNT) is all over the surface2 Many devices can be patterned anywhere on the substrate3 Unwanted silicon or SWNTs can be removed via etching4 SOI and NOI offer minimized parasitic capacitance faster switching speed
and lower dynamic power consumption
Common FeaturesCommon Features11 Active material (Si or SWNT) is all over the surfaceActive material (Si or SWNT) is all over the surface22 Many devices can be patterned anywhere on the substrateMany devices can be patterned anywhere on the substrate33 Unwanted silicon or Unwanted silicon or SWNTsSWNTs can be removed via etchingcan be removed via etching44 SOI and NOI offer minimized parasitic capacitance faster switchSOI and NOI offer minimized parasitic capacitance faster switching speed ing speed
and lower dynamic power consumptionand lower dynamic power consumption Zhou et al Nano Letters (2006)
a-Sapphire
Wafer-Scale Aligned Nanotube SynthesisWafer-Scale Aligned Nanotube Synthesis
1200
1000
800
600
400
200
Tem
pera
ture
200150100500
Time (min)
Growth Annealing
Key meticulous temperature control amp uniform growth
1μm
Quartz 1000
800
600
400
200Tem
pera
ture
6004002000
Time (min)
Growth Annealing
1μm
4 inch substrate
Gas in
Gas out
Quartz or Sapphire with patterned
catalyst
9 feet-long growth furnace with three-zone
Wafer-Scale CNT TransferWafer-Scale CNT TransferTransfer fullTransfer full--wafer of wafer of CNTsCNTs from quartz growth substrate to SiOfrom quartz growth substrate to SiO22Si fabrication Si fabrication
substrate substrate allows largeallows large--scale integrationscale integration
Nano Lett 9 189ndash197 20094
Wafer-Scale Aligned Nanotube Device FabricationWafer-Scale Aligned Nanotube Device Fabrication
Back-Gated Submicron TransistorsBack-Gated Submicron Transistors
Back-gated transistors
1 microm
L = 1 microm
1 microm
L = 075 microm
1 microm
L = 05 microm
I-Vg curves Channel length dependence
-120
-100
-80
-60
-40
-20
0
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
-60
-40
-20
0
I ds (μ
Α)
-1500Vds (V)
-1 V
-08 V
-06 V
-04 V
-02 V
Vg from -8V to 8V
15
10
05
I ds (m
A)
-10 -5 0 5 10Vg (V)
L = 05 microm L = 075 microm L = 1 microm L = 2 microm L = 5 microm L = 10 microm L = 20 microm
80
60
40
20
gm
(μ S
)
5 6 7 81
2 3 4 5 6 7 810
2
L(μm)
2
4
6810-6
2
4
6810-5
I DW
(mA
microm
) gm
Ion Ioff
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Calculation of Lennard-Jones Potential Calculation of Lennard-Jones Potential
sumsum⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
minusminus⎟
⎟
⎠
⎞
⎜⎜
⎝
⎛
minus+
⎥⎥
⎦
⎤
⎢⎢
⎣
⎡
⎟⎟⎠
⎞⎜⎜⎝
⎛
minusminus⎟
⎟⎠
⎞⎜⎜⎝
⎛
minus=
j j
CAl
j
CAlCAl
i i
CO
i
COCO rrrrrrrr
rU
612612
44)( vvvvvvvvv σσ
εσσ
ε
a carbon atom and oxygen atoms in sapphire
a carbon atom and oxygen atoms in sapphire
a carbon atom and Al atoms in sapphire
a carbon atom and Al atoms in sapphire
Interaction between
Interaction between
C-plane C-plane a-plane a-plane
Potential wellPotential wellZhou Zhou et alet al JPCC JPCC 112 15929 (200(20088))
Synthesis of Nanotubes with Controlled Orientations and Positions
Synthesis of Nanotubes with Controlled Orientations and Positions
Catalyst
Photo Resist
QuartzSapphire
Catalyst Island
Aligned NanotubesMetal Electrode
SD
G
Dielectric Layer
3-10 nanotubes microm
Aligned Nanotubes on Quartz Using Patterned CatalystAligned Nanotubes on Quartz Using Patterned Catalystcatalyst
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
(a)
Poly Si Gate
Gate Oxide
SourceDrain Electrode
(b)
NanotubeGate Dielectric
Gate
SourceDrain Electrode
Comparison between Silicon-on-insulator (SOI) and Nanotube-on-Insulator (NOI)
Comparison between SiliconComparison between Silicon--onon--insulator (SOI) and insulator (SOI) and NanotubeNanotube--onon--Insulator (NOI)Insulator (NOI)
SOISOISOI NOINOINOI
Common Features1 Active material (Si or SWNT) is all over the surface2 Many devices can be patterned anywhere on the substrate3 Unwanted silicon or SWNTs can be removed via etching4 SOI and NOI offer minimized parasitic capacitance faster switching speed
and lower dynamic power consumption
Common FeaturesCommon Features11 Active material (Si or SWNT) is all over the surfaceActive material (Si or SWNT) is all over the surface22 Many devices can be patterned anywhere on the substrateMany devices can be patterned anywhere on the substrate33 Unwanted silicon or Unwanted silicon or SWNTsSWNTs can be removed via etchingcan be removed via etching44 SOI and NOI offer minimized parasitic capacitance faster switchSOI and NOI offer minimized parasitic capacitance faster switching speed ing speed
and lower dynamic power consumptionand lower dynamic power consumption Zhou et al Nano Letters (2006)
a-Sapphire
Wafer-Scale Aligned Nanotube SynthesisWafer-Scale Aligned Nanotube Synthesis
1200
1000
800
600
400
200
Tem
pera
ture
200150100500
Time (min)
Growth Annealing
Key meticulous temperature control amp uniform growth
1μm
Quartz 1000
800
600
400
200Tem
pera
ture
6004002000
Time (min)
Growth Annealing
1μm
4 inch substrate
Gas in
Gas out
Quartz or Sapphire with patterned
catalyst
9 feet-long growth furnace with three-zone
Wafer-Scale CNT TransferWafer-Scale CNT TransferTransfer fullTransfer full--wafer of wafer of CNTsCNTs from quartz growth substrate to SiOfrom quartz growth substrate to SiO22Si fabrication Si fabrication
substrate substrate allows largeallows large--scale integrationscale integration
Nano Lett 9 189ndash197 20094
Wafer-Scale Aligned Nanotube Device FabricationWafer-Scale Aligned Nanotube Device Fabrication
Back-Gated Submicron TransistorsBack-Gated Submicron Transistors
Back-gated transistors
1 microm
L = 1 microm
1 microm
L = 075 microm
1 microm
L = 05 microm
I-Vg curves Channel length dependence
-120
-100
-80
-60
-40
-20
0
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
-60
-40
-20
0
I ds (μ
Α)
-1500Vds (V)
-1 V
-08 V
-06 V
-04 V
-02 V
Vg from -8V to 8V
15
10
05
I ds (m
A)
-10 -5 0 5 10Vg (V)
L = 05 microm L = 075 microm L = 1 microm L = 2 microm L = 5 microm L = 10 microm L = 20 microm
80
60
40
20
gm
(μ S
)
5 6 7 81
2 3 4 5 6 7 810
2
L(μm)
2
4
6810-6
2
4
6810-5
I DW
(mA
microm
) gm
Ion Ioff
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Synthesis of Nanotubes with Controlled Orientations and Positions
Synthesis of Nanotubes with Controlled Orientations and Positions
Catalyst
Photo Resist
QuartzSapphire
Catalyst Island
Aligned NanotubesMetal Electrode
SD
G
Dielectric Layer
3-10 nanotubes microm
Aligned Nanotubes on Quartz Using Patterned CatalystAligned Nanotubes on Quartz Using Patterned Catalystcatalyst
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
(a)
Poly Si Gate
Gate Oxide
SourceDrain Electrode
(b)
NanotubeGate Dielectric
Gate
SourceDrain Electrode
Comparison between Silicon-on-insulator (SOI) and Nanotube-on-Insulator (NOI)
Comparison between SiliconComparison between Silicon--onon--insulator (SOI) and insulator (SOI) and NanotubeNanotube--onon--Insulator (NOI)Insulator (NOI)
SOISOISOI NOINOINOI
Common Features1 Active material (Si or SWNT) is all over the surface2 Many devices can be patterned anywhere on the substrate3 Unwanted silicon or SWNTs can be removed via etching4 SOI and NOI offer minimized parasitic capacitance faster switching speed
and lower dynamic power consumption
Common FeaturesCommon Features11 Active material (Si or SWNT) is all over the surfaceActive material (Si or SWNT) is all over the surface22 Many devices can be patterned anywhere on the substrateMany devices can be patterned anywhere on the substrate33 Unwanted silicon or Unwanted silicon or SWNTsSWNTs can be removed via etchingcan be removed via etching44 SOI and NOI offer minimized parasitic capacitance faster switchSOI and NOI offer minimized parasitic capacitance faster switching speed ing speed
and lower dynamic power consumptionand lower dynamic power consumption Zhou et al Nano Letters (2006)
a-Sapphire
Wafer-Scale Aligned Nanotube SynthesisWafer-Scale Aligned Nanotube Synthesis
1200
1000
800
600
400
200
Tem
pera
ture
200150100500
Time (min)
Growth Annealing
Key meticulous temperature control amp uniform growth
1μm
Quartz 1000
800
600
400
200Tem
pera
ture
6004002000
Time (min)
Growth Annealing
1μm
4 inch substrate
Gas in
Gas out
Quartz or Sapphire with patterned
catalyst
9 feet-long growth furnace with three-zone
Wafer-Scale CNT TransferWafer-Scale CNT TransferTransfer fullTransfer full--wafer of wafer of CNTsCNTs from quartz growth substrate to SiOfrom quartz growth substrate to SiO22Si fabrication Si fabrication
substrate substrate allows largeallows large--scale integrationscale integration
Nano Lett 9 189ndash197 20094
Wafer-Scale Aligned Nanotube Device FabricationWafer-Scale Aligned Nanotube Device Fabrication
Back-Gated Submicron TransistorsBack-Gated Submicron Transistors
Back-gated transistors
1 microm
L = 1 microm
1 microm
L = 075 microm
1 microm
L = 05 microm
I-Vg curves Channel length dependence
-120
-100
-80
-60
-40
-20
0
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
-60
-40
-20
0
I ds (μ
Α)
-1500Vds (V)
-1 V
-08 V
-06 V
-04 V
-02 V
Vg from -8V to 8V
15
10
05
I ds (m
A)
-10 -5 0 5 10Vg (V)
L = 05 microm L = 075 microm L = 1 microm L = 2 microm L = 5 microm L = 10 microm L = 20 microm
80
60
40
20
gm
(μ S
)
5 6 7 81
2 3 4 5 6 7 810
2
L(μm)
2
4
6810-6
2
4
6810-5
I DW
(mA
microm
) gm
Ion Ioff
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
3-10 nanotubes microm
Aligned Nanotubes on Quartz Using Patterned CatalystAligned Nanotubes on Quartz Using Patterned Catalystcatalyst
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
(a)
Poly Si Gate
Gate Oxide
SourceDrain Electrode
(b)
NanotubeGate Dielectric
Gate
SourceDrain Electrode
Comparison between Silicon-on-insulator (SOI) and Nanotube-on-Insulator (NOI)
Comparison between SiliconComparison between Silicon--onon--insulator (SOI) and insulator (SOI) and NanotubeNanotube--onon--Insulator (NOI)Insulator (NOI)
SOISOISOI NOINOINOI
Common Features1 Active material (Si or SWNT) is all over the surface2 Many devices can be patterned anywhere on the substrate3 Unwanted silicon or SWNTs can be removed via etching4 SOI and NOI offer minimized parasitic capacitance faster switching speed
and lower dynamic power consumption
Common FeaturesCommon Features11 Active material (Si or SWNT) is all over the surfaceActive material (Si or SWNT) is all over the surface22 Many devices can be patterned anywhere on the substrateMany devices can be patterned anywhere on the substrate33 Unwanted silicon or Unwanted silicon or SWNTsSWNTs can be removed via etchingcan be removed via etching44 SOI and NOI offer minimized parasitic capacitance faster switchSOI and NOI offer minimized parasitic capacitance faster switching speed ing speed
and lower dynamic power consumptionand lower dynamic power consumption Zhou et al Nano Letters (2006)
a-Sapphire
Wafer-Scale Aligned Nanotube SynthesisWafer-Scale Aligned Nanotube Synthesis
1200
1000
800
600
400
200
Tem
pera
ture
200150100500
Time (min)
Growth Annealing
Key meticulous temperature control amp uniform growth
1μm
Quartz 1000
800
600
400
200Tem
pera
ture
6004002000
Time (min)
Growth Annealing
1μm
4 inch substrate
Gas in
Gas out
Quartz or Sapphire with patterned
catalyst
9 feet-long growth furnace with three-zone
Wafer-Scale CNT TransferWafer-Scale CNT TransferTransfer fullTransfer full--wafer of wafer of CNTsCNTs from quartz growth substrate to SiOfrom quartz growth substrate to SiO22Si fabrication Si fabrication
substrate substrate allows largeallows large--scale integrationscale integration
Nano Lett 9 189ndash197 20094
Wafer-Scale Aligned Nanotube Device FabricationWafer-Scale Aligned Nanotube Device Fabrication
Back-Gated Submicron TransistorsBack-Gated Submicron Transistors
Back-gated transistors
1 microm
L = 1 microm
1 microm
L = 075 microm
1 microm
L = 05 microm
I-Vg curves Channel length dependence
-120
-100
-80
-60
-40
-20
0
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
-60
-40
-20
0
I ds (μ
Α)
-1500Vds (V)
-1 V
-08 V
-06 V
-04 V
-02 V
Vg from -8V to 8V
15
10
05
I ds (m
A)
-10 -5 0 5 10Vg (V)
L = 05 microm L = 075 microm L = 1 microm L = 2 microm L = 5 microm L = 10 microm L = 20 microm
80
60
40
20
gm
(μ S
)
5 6 7 81
2 3 4 5 6 7 810
2
L(μm)
2
4
6810-6
2
4
6810-5
I DW
(mA
microm
) gm
Ion Ioff
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesTraditional Nanotube SynthesisTraditional Nanotube SynthesisAligned Nanotube SynthesisAligned Nanotube SynthesisFullFull--wafer Processing of Aligned Nanotube Electronicswafer Processing of Aligned Nanotube Electronics
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
(a)
Poly Si Gate
Gate Oxide
SourceDrain Electrode
(b)
NanotubeGate Dielectric
Gate
SourceDrain Electrode
Comparison between Silicon-on-insulator (SOI) and Nanotube-on-Insulator (NOI)
Comparison between SiliconComparison between Silicon--onon--insulator (SOI) and insulator (SOI) and NanotubeNanotube--onon--Insulator (NOI)Insulator (NOI)
SOISOISOI NOINOINOI
Common Features1 Active material (Si or SWNT) is all over the surface2 Many devices can be patterned anywhere on the substrate3 Unwanted silicon or SWNTs can be removed via etching4 SOI and NOI offer minimized parasitic capacitance faster switching speed
and lower dynamic power consumption
Common FeaturesCommon Features11 Active material (Si or SWNT) is all over the surfaceActive material (Si or SWNT) is all over the surface22 Many devices can be patterned anywhere on the substrateMany devices can be patterned anywhere on the substrate33 Unwanted silicon or Unwanted silicon or SWNTsSWNTs can be removed via etchingcan be removed via etching44 SOI and NOI offer minimized parasitic capacitance faster switchSOI and NOI offer minimized parasitic capacitance faster switching speed ing speed
and lower dynamic power consumptionand lower dynamic power consumption Zhou et al Nano Letters (2006)
a-Sapphire
Wafer-Scale Aligned Nanotube SynthesisWafer-Scale Aligned Nanotube Synthesis
1200
1000
800
600
400
200
Tem
pera
ture
200150100500
Time (min)
Growth Annealing
Key meticulous temperature control amp uniform growth
1μm
Quartz 1000
800
600
400
200Tem
pera
ture
6004002000
Time (min)
Growth Annealing
1μm
4 inch substrate
Gas in
Gas out
Quartz or Sapphire with patterned
catalyst
9 feet-long growth furnace with three-zone
Wafer-Scale CNT TransferWafer-Scale CNT TransferTransfer fullTransfer full--wafer of wafer of CNTsCNTs from quartz growth substrate to SiOfrom quartz growth substrate to SiO22Si fabrication Si fabrication
substrate substrate allows largeallows large--scale integrationscale integration
Nano Lett 9 189ndash197 20094
Wafer-Scale Aligned Nanotube Device FabricationWafer-Scale Aligned Nanotube Device Fabrication
Back-Gated Submicron TransistorsBack-Gated Submicron Transistors
Back-gated transistors
1 microm
L = 1 microm
1 microm
L = 075 microm
1 microm
L = 05 microm
I-Vg curves Channel length dependence
-120
-100
-80
-60
-40
-20
0
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
-60
-40
-20
0
I ds (μ
Α)
-1500Vds (V)
-1 V
-08 V
-06 V
-04 V
-02 V
Vg from -8V to 8V
15
10
05
I ds (m
A)
-10 -5 0 5 10Vg (V)
L = 05 microm L = 075 microm L = 1 microm L = 2 microm L = 5 microm L = 10 microm L = 20 microm
80
60
40
20
gm
(μ S
)
5 6 7 81
2 3 4 5 6 7 810
2
L(μm)
2
4
6810-6
2
4
6810-5
I DW
(mA
microm
) gm
Ion Ioff
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
(a)
Poly Si Gate
Gate Oxide
SourceDrain Electrode
(b)
NanotubeGate Dielectric
Gate
SourceDrain Electrode
Comparison between Silicon-on-insulator (SOI) and Nanotube-on-Insulator (NOI)
Comparison between SiliconComparison between Silicon--onon--insulator (SOI) and insulator (SOI) and NanotubeNanotube--onon--Insulator (NOI)Insulator (NOI)
SOISOISOI NOINOINOI
Common Features1 Active material (Si or SWNT) is all over the surface2 Many devices can be patterned anywhere on the substrate3 Unwanted silicon or SWNTs can be removed via etching4 SOI and NOI offer minimized parasitic capacitance faster switching speed
and lower dynamic power consumption
Common FeaturesCommon Features11 Active material (Si or SWNT) is all over the surfaceActive material (Si or SWNT) is all over the surface22 Many devices can be patterned anywhere on the substrateMany devices can be patterned anywhere on the substrate33 Unwanted silicon or Unwanted silicon or SWNTsSWNTs can be removed via etchingcan be removed via etching44 SOI and NOI offer minimized parasitic capacitance faster switchSOI and NOI offer minimized parasitic capacitance faster switching speed ing speed
and lower dynamic power consumptionand lower dynamic power consumption Zhou et al Nano Letters (2006)
a-Sapphire
Wafer-Scale Aligned Nanotube SynthesisWafer-Scale Aligned Nanotube Synthesis
1200
1000
800
600
400
200
Tem
pera
ture
200150100500
Time (min)
Growth Annealing
Key meticulous temperature control amp uniform growth
1μm
Quartz 1000
800
600
400
200Tem
pera
ture
6004002000
Time (min)
Growth Annealing
1μm
4 inch substrate
Gas in
Gas out
Quartz or Sapphire with patterned
catalyst
9 feet-long growth furnace with three-zone
Wafer-Scale CNT TransferWafer-Scale CNT TransferTransfer fullTransfer full--wafer of wafer of CNTsCNTs from quartz growth substrate to SiOfrom quartz growth substrate to SiO22Si fabrication Si fabrication
substrate substrate allows largeallows large--scale integrationscale integration
Nano Lett 9 189ndash197 20094
Wafer-Scale Aligned Nanotube Device FabricationWafer-Scale Aligned Nanotube Device Fabrication
Back-Gated Submicron TransistorsBack-Gated Submicron Transistors
Back-gated transistors
1 microm
L = 1 microm
1 microm
L = 075 microm
1 microm
L = 05 microm
I-Vg curves Channel length dependence
-120
-100
-80
-60
-40
-20
0
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
-60
-40
-20
0
I ds (μ
Α)
-1500Vds (V)
-1 V
-08 V
-06 V
-04 V
-02 V
Vg from -8V to 8V
15
10
05
I ds (m
A)
-10 -5 0 5 10Vg (V)
L = 05 microm L = 075 microm L = 1 microm L = 2 microm L = 5 microm L = 10 microm L = 20 microm
80
60
40
20
gm
(μ S
)
5 6 7 81
2 3 4 5 6 7 810
2
L(μm)
2
4
6810-6
2
4
6810-5
I DW
(mA
microm
) gm
Ion Ioff
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
a-Sapphire
Wafer-Scale Aligned Nanotube SynthesisWafer-Scale Aligned Nanotube Synthesis
1200
1000
800
600
400
200
Tem
pera
ture
200150100500
Time (min)
Growth Annealing
Key meticulous temperature control amp uniform growth
1μm
Quartz 1000
800
600
400
200Tem
pera
ture
6004002000
Time (min)
Growth Annealing
1μm
4 inch substrate
Gas in
Gas out
Quartz or Sapphire with patterned
catalyst
9 feet-long growth furnace with three-zone
Wafer-Scale CNT TransferWafer-Scale CNT TransferTransfer fullTransfer full--wafer of wafer of CNTsCNTs from quartz growth substrate to SiOfrom quartz growth substrate to SiO22Si fabrication Si fabrication
substrate substrate allows largeallows large--scale integrationscale integration
Nano Lett 9 189ndash197 20094
Wafer-Scale Aligned Nanotube Device FabricationWafer-Scale Aligned Nanotube Device Fabrication
Back-Gated Submicron TransistorsBack-Gated Submicron Transistors
Back-gated transistors
1 microm
L = 1 microm
1 microm
L = 075 microm
1 microm
L = 05 microm
I-Vg curves Channel length dependence
-120
-100
-80
-60
-40
-20
0
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
-60
-40
-20
0
I ds (μ
Α)
-1500Vds (V)
-1 V
-08 V
-06 V
-04 V
-02 V
Vg from -8V to 8V
15
10
05
I ds (m
A)
-10 -5 0 5 10Vg (V)
L = 05 microm L = 075 microm L = 1 microm L = 2 microm L = 5 microm L = 10 microm L = 20 microm
80
60
40
20
gm
(μ S
)
5 6 7 81
2 3 4 5 6 7 810
2
L(μm)
2
4
6810-6
2
4
6810-5
I DW
(mA
microm
) gm
Ion Ioff
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Wafer-Scale CNT TransferWafer-Scale CNT TransferTransfer fullTransfer full--wafer of wafer of CNTsCNTs from quartz growth substrate to SiOfrom quartz growth substrate to SiO22Si fabrication Si fabrication
substrate substrate allows largeallows large--scale integrationscale integration
Nano Lett 9 189ndash197 20094
Wafer-Scale Aligned Nanotube Device FabricationWafer-Scale Aligned Nanotube Device Fabrication
Back-Gated Submicron TransistorsBack-Gated Submicron Transistors
Back-gated transistors
1 microm
L = 1 microm
1 microm
L = 075 microm
1 microm
L = 05 microm
I-Vg curves Channel length dependence
-120
-100
-80
-60
-40
-20
0
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
-60
-40
-20
0
I ds (μ
Α)
-1500Vds (V)
-1 V
-08 V
-06 V
-04 V
-02 V
Vg from -8V to 8V
15
10
05
I ds (m
A)
-10 -5 0 5 10Vg (V)
L = 05 microm L = 075 microm L = 1 microm L = 2 microm L = 5 microm L = 10 microm L = 20 microm
80
60
40
20
gm
(μ S
)
5 6 7 81
2 3 4 5 6 7 810
2
L(μm)
2
4
6810-6
2
4
6810-5
I DW
(mA
microm
) gm
Ion Ioff
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Wafer-Scale Aligned Nanotube Device FabricationWafer-Scale Aligned Nanotube Device Fabrication
Back-Gated Submicron TransistorsBack-Gated Submicron Transistors
Back-gated transistors
1 microm
L = 1 microm
1 microm
L = 075 microm
1 microm
L = 05 microm
I-Vg curves Channel length dependence
-120
-100
-80
-60
-40
-20
0
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
-60
-40
-20
0
I ds (μ
Α)
-1500Vds (V)
-1 V
-08 V
-06 V
-04 V
-02 V
Vg from -8V to 8V
15
10
05
I ds (m
A)
-10 -5 0 5 10Vg (V)
L = 05 microm L = 075 microm L = 1 microm L = 2 microm L = 5 microm L = 10 microm L = 20 microm
80
60
40
20
gm
(μ S
)
5 6 7 81
2 3 4 5 6 7 810
2
L(μm)
2
4
6810-6
2
4
6810-5
I DW
(mA
microm
) gm
Ion Ioff
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Back-Gated Submicron TransistorsBack-Gated Submicron Transistors
Back-gated transistors
1 microm
L = 1 microm
1 microm
L = 075 microm
1 microm
L = 05 microm
I-Vg curves Channel length dependence
-120
-100
-80
-60
-40
-20
0
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
-60
-40
-20
0
I ds (μ
Α)
-1500Vds (V)
-1 V
-08 V
-06 V
-04 V
-02 V
Vg from -8V to 8V
15
10
05
I ds (m
A)
-10 -5 0 5 10Vg (V)
L = 05 microm L = 075 microm L = 1 microm L = 2 microm L = 5 microm L = 10 microm L = 20 microm
80
60
40
20
gm
(μ S
)
5 6 7 81
2 3 4 5 6 7 810
2
L(μm)
2
4
6810-6
2
4
6810-5
I DW
(mA
microm
) gm
Ion Ioff
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Top-gated transistors
075 μmG
S
D
Al2O3
15
10
5
0
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
10-8
10-7
10-6
10-5
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
15
10
5
0
-5
-10
-15
I ds (μ
Α)
-10 -05 00 05 10Vds (V)
I-Vg curves I-Vds curves
Top-Gated Submicron TransistorsTop-Gated Submicron Transistors
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
N-type nanotube transistorsN-type nanotube transistorsHydrazine(NHydrazine(N22HH44) doping) doping
12
10
08
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds =01 V Vds =03 V Vds =05 V Vds =07 V Vds =09 V Vds =11 V
Before
06
04
02
00
I ds (μ
Α)
-10 -5 0 5 10Vg (V)
Vds=01 VVds=03 VVds=05VVds=07 VVds=09 VVds=11 V
After
Gain asymp54
10
08
06
04
02
00
Vou
t (V)
50454035302520
Vin (V)
6
5
4
3
2
1
0
I (nA)
Vout
I
Inverter
Gain =54
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
K doping
10
8
6
4
2
I ds (μ
Α)
-4 -2 0 2 4Vg (V)
Before K doping After K doping
Gain asymp 5
p-type
n-type
15
10
05
00V
out (
V)
252015100500
Vin (V)
Gain=5
Potassium Doping and CMOS InverterPotassium Doping and CMOS Inverter
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
CMOS NAND amp NORCMOS NAND amp NORIndividual back-gated
NOR NAND
10
08
06
04
02
00
Vou
t (V
)
Gate AGate B
11
10
01
00
10 μm 10 μm10 μm
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
httpwwwfibre2fashioncom Defense Science Journal Vol 55 No 2
Flexible electronics and smart textiles
Flexible electronics and smart textiles for ubiquitous computing and sensing for daily life and battle field applications
Carbon nanotubes due to their high flexibility and superior chemical sensing performances
Nature news
Robot with sensitive skin
Soldier in the future
Oak Ridge National Laboratory
Artificial muscle
11
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
1 Au layer deposition
2 Peeling off nanotubes
3 Transferring nanotubes
4 Etch away Au layer
Nanotube Transfer for Wearable ElectronicsNanotube Transfer for Wearable Electronics
Transferring yield of nanotubes Transferring yield of nanotubes congcong 100 100
Quartz
NanotubeThermal tape
Gold film
Target substrate
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
a Perpendicular transfer on SiSiO2
1st transferred layer
2st transferred layer
b 60 degree transfer
Carbon Nanotube ldquoFabricrdquoCarbon Nanotube ldquoFabricrdquo
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
On PETOn glass rod On Fabric
SEM image of transferred aligned SWNT
On glass slide
Nanotubes can be transferred on all kinds of substrates
Transferred nanotubes
Transferred nanotubes on various subTransferred nanotubes on various sub
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Wearable Transistors Transistor on FabricWearable Transistors Transistor on Fabric-20nm Ti back gate-TiAu as SD electrode-1microm SU8 as a dielectric
-onoff ratio cong 104
-Subthreshold swing(S) cong 500mVdecade
-14
-12
-10
-8
-6
-4
-2
0
I (μ
Α)
-5 -4 -3 -2 -1 0Vds (V)
5
4
3
2
1
625
20
15
10
05
00
I (μ
Α)
-20 -10 0 10 20Vg (V)
5
4
32
1
10-11
10-9
10-7
I (μ
Α)
-20 -10 0 10 20Vg (V)
10-9
10-8
10-7
10-6
10-5
I (μ
Α)
-20 -10 0 10 20Vg (V)
Before After
Electrical breakdown I ndashVg curves I ndashVds curves
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Wearable Transistors Chemical sensingWearable Transistors Chemical sensingTNT (Trinitrotoluene) sensing
-06
-04
-02
00
ΔG
G0
14x103121086420
time(s)
015 ppm02 ppm
04 ppm
06 ppm
11 ppm
23 ppb60 ppb
8ppb
Introduce gas
UV off
UV on
Detection limit asymp below ppb
TNTBenzene NO
+lightTiPd
Fabric coated withPolyethylene
NO2 sensing
025
020
015
010
005
000Δ
GG
0160012008004000
Time (sec)
80 ppb 150 ppb 125 ppm 25 ppm 5 ppm
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire TransistorsNanowire Transistors
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
SnO2
InP
Fe3O4
2 μm
InN
GaN
ZnO In2O3
CdO
Si
Adv Mat 15 143 (2003)Adv Mat 15 1754 (2003)APL 82 1950 (2003)
APL 88 133109 (2006) Nature Nanotech 2 378 (2007)Nano Letters 8 997 (2008)
Synthesis of Novel Nanowires
Nano Letters 4 1241 (2004)Nano Letters 4 2151 (2004)Adv Mat 17 1548 (2005)JACS 127 6 (2005)
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Evolution of Display technologies
1st
CRTInorganic ELElectron-Gun
PDP LCD
PlasmaColor FilterBack light
OLEDOrganic EL
Self-emitting
4th
FTNDFlexible amp Transparent
Display
Cutting-Edge Technology RequiredGenerations of Display Technologies
2nd 3rd
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Flexible Electronics
Portable and flexibleRigid heavy and breakable -gt Light unbreakable and flexible
Applications
WristbandDisplays
RollableNewspapers
Transparent Electronics
TransparentNontransparent -gt Transparent Easy-to-read
Applications
Head-up Displays
Transparent Monitors
Transparent Televisions
Windshields of cars
W i N d O W S
Paper Computers
Rollable Displays
Why Transparent and Flexible
Need New Materials to Achieve This Goal
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
α-Si TFTs - High Reliability- Presently used in LCDs- High Reliability- Presently used in LCDs
Poly-Si TFTs - High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs- High mobilities (~ gt150 cm2Vsec)- Presently used in AMOLEDs
Nanowires Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Overcome from (a) to (e)- High mobilities (~500-4000 cm2Vsec)- Low temperature processing can use on plastic substrate
Displays Advantage
- Low temperature processingcan use on plastic substrates
- Low temperature processingcan use on plastic substrates
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(a) High temperature processingdifficult to use on plastic
(b) Low mobilities (μ le 1 cm2Vsec)
(c) High temperature processingdifficult to use on plastic substrates
(c) High temperature processingdifficult to use on plastic substrates
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
No Current Development (High Risk)- Nanowire alignmentassembly- Uniformity- Yield
ChallengeRequired Solution
(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity(d) Low mobilities (μ le 1 cm2Vsec)(e) Temperature and moisture sensitivity
ldquoNew Display Concepts using Hybrid Organic-Nanowire Structuresrdquo
Includes all advantages of current flat panel displays (LCD PDP AMOLED) and overcomes conventional displayrsquos limitations
Why Nanowires
OTFTs
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Synthesis of In2O3 Nanowires Laser AblationSynthesis of In2O3 Nanowires Laser Ablation
AFM image of Au clusters on SiSiO2
2 μm
InAs Target
In2O3 nanowires
Length 3 ndash 5 μm
Zhou et al Adv Mat 15 143 (2003)
Growth conditionT 770 oC
Pressure 100 ndash 700 Torr
Gas Ar + O2
LaserGas
Substrate with Au clusters
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
In2O3 Nanowires Material AnalysisIn2O3 Nanowires Material Analysis
XRD TEM highXRD TEM high--resolution TEMresolution TEM
Cubic crystal structure a = 101 nmGrowth direction [110]Advantage no amorphous coating reliable electrical contacts and operation
072nm
[110]
100 nm
[110]
AuIn Particle
Inte
nsity
(a u
)
60504030202 theta (degree)
In2O3 (222)
In2O3 (400)
In2O3 (440)
Au (111) Au (200)
In2O3 (622)
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
In2O3 Nanowire TransistorIn2O3 Nanowire Transistor
1 N-type semiconductor due to oxygen vacancies and In interstitials2 On off ratio 11 times 105
1000
500
0
-500
-1000
I (nA
)
-10 -05 00 05 10Vds (V)
10 V
V g = 15 V
7 V 0 V
-7 V
-10 V
600
400
200
0I (
nA)
1050-5-10Vg (V)
Vds = 032 V300 K
APL 82 112 (2003)
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Fully transparent transistor using oxide nanowiresFully transparent transistor using oxide nanowires
15 um
ITO S
ITO D
IZO G
In2O3 NWDiameter ~20 nm
In2O3 nanowire as transparent transistor active channel
bull Highly transparent (intrinsic transparency amp small dimension)
bull Low temperature processbull High mobility (single crystal)
In2O3 NWALD Al2O3ltDevice structuregt
Nature Nanotechnology 2007
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
High performance transistorHigh performance transistor
Mobility 514 to 300 cm2VsSubthreshold 160 mVdecOnoff ratio 106
Transmittance ~82 (including substrate)
Nature Nanotechnology 2007
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Transparent amp flexible transistorsTransparent amp flexible transistors
Device on PET
Mobility 120 to 167 cm2VsSubthreshold 900 mVdecOnoff ratio 105
Nature Nanotechnology 2007
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Application of transparent transistors for AMOLED circuitApplication of transparent transistors for AMOLED circuit
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
Scan
T1T3
Data (Vg2)
Cst
(Vg1)
T2
Vdd
OLED
(a) (b) (c)
Highlights of Recent Results Initial Circuit Demonstration (Green AM OLED Display)
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Chemical Sensing Based on In2O3 NanowiresChemical Sensing Based on In2O3 Nanowires
ON
In
In2O3nanowire
SiSiO2 back gate
TiAu electrodes
Advantage of In2O3 nanowires1 Single crystal 2 No amorphous coating (as compared to Si NWs with amorphous SiO2)3 High surface-to-volume ratio
Operation principle NO2 molecules withdraw electrons from In2O3Operation principle NO2 molecules withdraw electrons from In2O3
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
A UV light illumination to recover the deviceB turn off UV C 20ppb NO2Ar
20ppb NO2 in air can be detectableDetect limit can be pushed to 5ppb NO2 in Ar
NO2 Sensing Based on In2O3 NanowiresNO2 Sensing Based on In2O3 NanowiresReal time detection and recovery using UV illumination
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
In2O3 Nanowire Sensors with Integrated HeatersIn2O3 Nanowire Sensors with Integrated Heaters
80
60
40
20
0
Nor
mal
ized
Con
duct
ance
()
4003002001000Time (s)
50 ppm20 ppm10 ppm1 ppm
Advantages
Ethanol Alcohol
Sensitive to hydrocarbonsFaster recoveryPotential to achieve good selectivity
heater
SiN membrane
sensor
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
OUTLINEOUTLINEIntroductionIntroduction
Carbon NanotubesCarbon NanotubesCarbon Nanotube InverterCarbon Nanotube InverterAligned Growth and NanotubeAligned Growth and Nanotube--onon--Insulator (NOI) Insulator (NOI) ApproachApproach
NanowiresNanowiresNanowire SynthesisNanowire SynthesisNanowire Transistors and MemoriesNanowire Transistors and Memories
ApplicationsApplicationsBiosensingBiosensingEnergy ConversionEnergy Conversion
ConclusionConclusion
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Nano-Biosensor and Nano-DiagnosisNano-Biosensor and Nano-Diagnosis
AdvantagesSmall nanoscale in-vivoSelectiveSensitive No amplification neededCheap disposableVersatileintegratable
ElectrodeNanowire Nanotube
Si Substrate
SiO2
Antigen
Antibody
Linker
Structure and PrincipleNanowire nanotube functionalized with linking moleculesProbe molecules (ss-DNA antibody) anchored to the surface via linkersSelective attachment of target molecules leads to a chemical gating effectResistance of the nanowire nanotube used as read-out
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Detection of Prostate Specific Antigen (PSA)Detection of Prostate Specific Antigen (PSA)
Si
AuTi
SiO2
PSA
PSAantibody
Linker
PSA
NWSWNT
(a)
NO O
OP
O O
O O
OP
O O
H O O
OP
O O
H N O
In2O3 NWi iiiii
(b)
O
O
NO
O
O
H N
SWNT iv v
(c)
PSA is a bio marker for the presence of prostate cancer which is the most frequently diagnosed cancer among
men in the US
Standard PSA
Probability of cancer
0-2 ngmL 12-4 ngmL 154-10 ngmL 25gt10 ngmL gt50
In2O3 Nanowire functionalization
Carbon Nanotube functionalization
In collaboration with Richard Cote of USC Center for Cancer ResearchIn collaboration with Richard Cote of USC Center for Cancer Research
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Selective Detection of Selective Detection of PSA PSA in PBS Bufferin PBS Buffer
Buffer BSA PSA
(a)
390
385
380
I (n
A)
5004003002001000Time (s)
252
248
244
240
I (μΑ
)
3000200010000Time (s)
BSA PSABuffer
(b)
Carbon Nanotube Mat Carbon Nanotube Mat Reduced ConductionReduced Conduction
Individual InIndividual In22OO33 Nanowire Nanowire Enhanced ConductionEnhanced Conduction
11 No response when BSA was addedNo response when BSA was added22 Detection of PSA down to 5 Detection of PSA down to 5 ngmLngmL achieved in PBS bufferachieved in PBS buffer
RealReal--time detection of PSA in aqueous environmenttime detection of PSA in aqueous environment
J Am Chem Soc 2005 127(36) 12484
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Integration of nanobiosensor and advanced microfluidics toward multiplexed sensingIntegration of nanobiosensor and advanced microfluidics toward multiplexed sensing
Microfabricatedvalves
Device region
functionalize nanobiosensor selectively using microfluidics system
Ab 1 Ab 2 Ab 3
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Integrated sensor and microfluidicsIntegrated sensor and microfluidics
source
drain
valves
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
-Higher Flexibility than ITO
-Transparent
-Most abundant element in nature
-Tunable eletronic properties
using Chemical treatment and enhanced carrier injection
CNT films as transparent conductive electrodes for Solar cell
Carbon Carbon NNanotubes for anotubes for EEnergy nergy CConversion onversion ((Solar cellSolar cell))
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Fabrication of CNT films
On Glass On Plastic Sub
CNT films on Filter membrane
Filter
PDMS
New Sub
PDMS
Dissolve arc discharge nanotubes In 1 SDS DI water (1mgml) using probesonicatorbullDilute by 30times with DI waterbullFiltration of this solution
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Application in Solar cell
AbsorptionExciton DiffusionCharge Separation
Exciton DissociationCharge Transport
Charge CollectionCathode (Electron)Anode (Hole) E
(eV
)
Evac = 0 eV
TCE CuPc C60 BCP
Al
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Plastic
CNT films
CuPc(donor)
C60 (acceptor)
BCP(Buffer)
Al
Application in Solar cell
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Device Structure Jsc (mAcm-2) Voc (V) FFEfficiency
()
PlasticITOOrganicAl 20 0410 051 037
PlasticSWNTHigh TransOrganicAl 22 0397 044 032
PlasticSWNTLow TransOrganicAl 14 0365 043 019
PEDOTPSSCuPcC60BCP
-04 -02 00 02 04 06
-2
-1
0
1
2 SWNTHigh Trans Dark SWNTHigh Trans Light SWNTLow Trans Dark SWNTLow Trans Light ITO Dark ITO Light
Voltage (V)
Cur
rent
den
sity
(mA
cm-2)
400 500 600 700 800 900 1000 1100
0
10
20
30
40
50
60
70
80
90Tr
ansm
ittan
ce (
)
Wavelength (nm)
PlasticSWNTHigh Trans
PlasticSWNTLow Trans
PlasticITO
In spite of the low SWNT transmittance this is comparable to the 20 mAcm-2 Jsc and 037 efficiency obtained from an identical device based on a 71 transmissive plasticIn2O3Sn electrode which underscores the prospect for improving OPVs by utilizing SWNT electrodes
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
Summary
1 Built one of the first integrated carbon nanotube inverter
2 Demonstrated growth of aligned single-walled carbon nanotubes and developed a nanotube-on-insulator approach
3 Developed a laser ablation approach for the synthesis of metal oxide nanowires
4 Demonstrated In2O3 nanowire transistor multilevel memory and chemical sensors
5 Nanotubes and nanowires have been used for complementary sensing of PSA
6 Nanotubes have been used as transparent conductive electrodes for solar cell
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu
THANK YOU THANK YOU
httphttpnanolabuscedunanolabuscedu