Jornada de InvestigaciJornada de Investigacióón y Desarrollo Tecnoln y Desarrollo Tecnolóógico gico -- 20032003
InstituteInstitute ofof OptoelectronicOptoelectronic SystemsSystemsandand MicrotecnologyMicrotecnology
Enrique CallejaEnrique Callejawww.isom.upm.es
MICINN - JST Joint Workshop on “Nanosciences and NewMaterials for Environmental Challenges”
Barcelona,March 10th -12th, 2010
ISOM ISOM -- ETSIT ETSIT -- UPMUPM
Research activity
Magnetic SensorsM
A
NAlGaN + ZnO UV PhotodetectorsNitride-based Solar Cells and IR detectorsWhite light generation with nanoLEDs arraysAlGaN/GaN HEMTs for high frequency and powerAlGaN MEMS/SAW for μW electronics and sensors
GaAs(In,N)-based IR photodetectors (QWIPs)InAs/GaInSbN Quantum DotsInGaAsN/GaAs Heterostructures (1.5 μm)
S Simulation of Non-Metallic Materials
ISOM ISOM -- ETSIT ETSIT -- UPMUPM
UV-X detectors(Bio / Space)
Blue Laser diodes(Storage/Comms)
RF power transistors(Wireless base stations)
Illumination(White-blue-UV LEDs)
Hydrogen generation(Fuel cells)
High frequency MMICs(Wireless Broadband)
Engine Electronics(Temperature Sensors)
Energy conversion(Photovoltaics)
Switches(Display panels)
MEMS(Pressure sensors)
Wide III-Nitrides applications
Ga(Al,In)N nanorods on Si(111), Si(100), Al2O3 and SiC/Si(111) GaN/Al2O3
AlGaN/Si(111)
GaN/Si(111)
GaN/SiC/Si(111)
III / V << 1
0.5 μm
Growth of III-Nitride Nanorods on Different Substrates
1μm1μm
InN/Si(111)
GaN/Si(100)
ISOM ISOM -- ETSIT ETSIT -- UPMUPM
Nanorods alignment
Si (111)
GaN [0001]
5 nm
m904
Structural characterization (TEM)
* HRTEM: nanorods without extended structural defects.aligned along the [0001] direction (c)sidewalls are atomically sharp {1100} facets. Strain free.
* SAED: nanorods are structurally uniform and single crystalline.
A. Trampert et al. IOP Conf.Ser. No. 180, 167 (2003).
L Cerutti et al.Appl. Phys.Lett., 88, 213114 (2006).
ISOM ISOM -- ETSIT ETSIT -- UPMUPM
AlGaN/GaN/AlGaN heterostructure withGaN QDiscs
10 nm
5 nm
c9 unit cells
~46 Å
Al content ≈ 20%
nominal thickness 4 nm
abrupt interfaces
[0001]
[1-100][11-20]
J. Ristic et al., phys. stat. sol. (a), 192, 60 (2002)
J. Ristic et al., Phys. Rev. B68, 125305 (2003)
ISOM ISOM -- ETSIT ETSIT -- UPMUPM
PL of GaN QDiscs in AlGaN nanorods
AlGaN cap (∝50 nm)
5 GaN QDswith AlGaNbarriers (∝10 nm)
320 nm
190 nm
3,2 3,4 3,6 3,8 4,0 4,2 4,4
m1090(2 nm)3.763 eV
3.591 eV
3.457 eV
m1096(4 nm)
m1085(3 nm) m1077
Ref. AlGaN
3.303 eV
x5
m1079(6 nm)
4.048 eV
Ar+SHG1mW8.5K
100μm
PL In
tens
ity(a
.u.)
Energy (eV)
Blue shift with decreasing QDisc thicknessQuite broad lineshapeStrong QCSE
PL intensity quenching due to Strain ConfinementJ. Ristic et al. Phys. Rev. B72, 085330 (2005).
ISOM ISOM -- ETSIT ETSIT -- UPMUPM
Nanocavity with Bragg Reflectors
GaN
AlN
AlNAlGaN
GaN QDs
J. Ristic, et al.,Phys.Rev.Lett., 94, 146102 (2005)
Nanocolumnar Homojunctions
Au:Be upper p-type contact (150 nm)
⇒ photolitography, reactive ion etching
EL spectrum dominated by Mg- related emission
p-n junction
m979d1 λS= 500 nm @ RT
m979d1
λS=380 nm @ 8K
m979d2
Cyan
Violet
ISOM ISOM -- ETSIT ETSIT -- UPMUPM
InN Nanorods on c-plane (Si(111)) and a-plane (a-GaN/r-Al2O3)
0.57 0.60 0.63 0.66 0.69 0.72 0.75
13 K 25 K 35 K 45 K 70 K 90 K
PL
Inte
nsity
(arb
.uni
ts)
Energy (eV)0 15 30 45 60 75 90 105 120 135 150 165 180
0.0
0.5
1.0
1.5
2.0
2.5
3.0
E2
Inte
nsity
(cts
/s)
Angle (º)
InN NCs on a-plane GaN GaN template (a-plane) InN NCs grown along the c-axis
J. Grandal et al. APL 94, 221908 (2009)
ISOM ISOM -- ETSIT ETSIT -- UPMUPM
Growth selectivity V/III ratio ~ 1500Constant diameter with pulsed MOCVDS.D. Hersee et al. Nanoletters, 6, 8, 1808 (2006)
Ordered GaN and InN nanorods
SiN nanohole mask
Y. Y. NanishiNanishi et al. et al. JpnJpn. J. . J. ApplAppl. Phys. 47, 5330 . Phys. 47, 5330 (2008)(2008)
GaNGaN template patterned by FIBtemplate patterned by FIB
H. Sekiguchi et al., Appl. Phys. Express 1, 124002 (2008)
Integrated PL intensity ratio 4/300K = 81%
Phosphor-free MBE grown white NanoLEDs
Emission from InGaN/GaN nanoLEDs grown on different Ti- nanoholes (same wafer)
ISOM ISOM -- ETSIT ETSIT -- UPMUPM
Core/Shell Nanowire LEDs by MOVPE
M. Lieber et al., Nano Lett., 4, 1975 (2004)
Growth process
I-V curve of a n-GaN/InGaN/p-GaN NW. Shell is etched by FIB for electrical contact
M. Lieber et al., NanoLett., 5, 2287, (2005)
1, 10, 20, 25, 35% In
ISOM ISOM -- ETSIT ETSIT -- UPMUPM
Nanrods merging
ISOM ISOM -- ETSIT ETSIT -- UPMUPM
Nano ELOG
Z. Bougrioua et al. Journal of Crystal Growth 309, 113 (2007)
• Crystalline Si current commercial concentrators typically ~25%. CHEAP.• High efficiency (~35%) for III-V/Ge multi-junctions. EXPENSIVE.
• III-nitrides have very strong band edge absorption coefficients (105 cm-1).• Active region of few hundreds nanometers, instead of hundreds of microns for Si.• Low carrier effective mass, high mobilities, and peak/saturation velocities.• Radiation tolerance for high efficiency solar cells used in outer space. • Easy to grow as thin films or ordered nanorods on cheap Si substrates.• Possibility to grow Nitride-cells on already fabricated Si-cells.• Spontaneous and piezoelectric internal fields beneficial for PV (carrier separation).• Use of InN/InGaN Quantum Wells (QWs) as “i” regions in p-i-n structures• Theoretical efficiencies > 40% with InGaN cells (3J + concentrator) • P-doping problems in InGaN with In%>50%. Japanese activity at Ritsumeikan U.
Photovoltaics using InGaN
� The direct energy gap of InGaN covers most of the solar spectrum
Photovoltaics using InGaN
In(Ga)N Nanowires and films grown on Si by MBE
(a) InN nanowire arrays grown on Si substrate by MBE. (b) The epitaxial interfacebetween the InN nanowire and Si where an AlN buffer layer was used
GaN
InGaN
200 nm
100-400 nm
I-V and Photovoltaics in InGaN/Si Nanorods
In-situ nanoprobe I-V by AFM
100 nm
tungstenprobe
InGaN
/ GaN
Si substrate
calculated
Si substrateBand Alignementproviding a tunel junction
Prediction: high PV efficiency in a double InGaN/Si junction .
Approaches
InGaN-based solar cells on sapphireor Silicon using thin films (In)GaN-based solar cells on Si
using Nitride Nanorods(Tang. NanoLetters, 8, 12, 4191 2008)
or Si
Photovoltaics using InGaN
• Solar Energy Materials Research Group, Lawrence Berkeley National Laboratory. Prof. W. Walukiewicz
• Nanophotonics Center, Arizona State University. Dr. Y.H. Zhang• Electro-Optics and Photonics Division, Army Research Labs. Dr. G.
Wood• “Very High Efficiency Solar Cell” (VHESC) DARPA programme
• School of Science and Eng. Ritsumeikan Univ. Japan. Prof. Y. Nanishi.
Activity in the Field:
Author Year Journal Fill Factor In (%) Eff (%){Int.}Liou 2009 Jap. J. Appl. Phys. 48,72201 89.5 to 91.8 60-90 33-38
Horng 2009 IEEE Electron Dev. Lett. 30, 021414 55-80
Sheu 2009 IEEE Electron Dev. Lett. 30, 2012275 0,25 58
McCormick 2009 MRS Bulletin 30, 151
Dahal 2009 Appl. Phys. Lett. 94 30 40-60
Tang 2008 Nano Letters 8, 4191 2,7
Chen 2008 Phys. Status Solidi (a) 205, 1103 61 0-30
Neufeld 2008 Appl. Phys. Lett. 93, 143502 75 12 60% EQE @390nm
Zimmler 2007 Nano Technology
Yang 2007 Phys. Status Solidi (a) 204, 4288 57 15-18
Jani 2007 Appl. Phys. Lett. 91, 132117 4-5
Hamzaoui 2005Solar Energy Mater. & Solar Cells 87, 595
28 (2J) to 40 (6J) calculated
Jani 2005 IEEE PV Specialist Conf 20057, 40 {~20}
Yamaguchi 20032003 International Symposium on
Compound Semiconductors42 100 50
Photovoltaics using InGaN
ISOM ISOM -- ETSIT ETSIT -- UPMUPM
Japanese-Spanish Cooperation
• ISOM-UPM. Prof. E. Calleja.• Universidad Autónoma de Madrid. Prof. J.M. Calleja• Instituto Jaume Almera, Barcelona, CSIC. Prof. L. Artús• School of Science and Eng. Ritsumeikan Univ. (Japan). Prof. Y. Nanishi
Common Activities: “High efficiency InGaN heterojunction Solar Cells grown by MBE”Coordination Action within the “Strategic Japanese-Spanish Cooperative Program”MICINN, PLE2009-0023. 2009-2012.
Japanese-Spanish-German Joint Workshop on Advanced Semiconductor Opto-electronic Materials and Devices. Since 2000. Next Edition in Madrid, March 2011.
• ISOM-UPM. Prof. E. Calleja.• School of Science and Eng. Ritsumeikan Univ. Japan. Prof. Yasushi Nanishi• Sophia University, Tokyo, Japan. Prof. Katsumi Kishino• Chiba Univ. Chiba, Japan. Prof. Akihiko Yoshikawa
Common publicationsVisit of Prof. Y. Nanishi to ISOM and Jaume Almera Institute, CSIC. (2008)Visit of Prof. K. Kishino to ISOM on March 23rd (2010)