Upload
others
View
9
Download
0
Embed Size (px)
Citation preview
©
Using Nanoelectrical Solutions to expand the capability of AFM Dr. Peter De Wolf [email protected]
mailto:[email protected]
©
Atomic Force Microscopy (AFM)
3/29/2018 2
• Microscopy technique based on raster-scanning and small tip-sample force interactions
• Resolution
© ©
Electrical Property Measurements with AFM
3/29/2018 3
Conductivity & Resistivity: C-AFM, TUNA, SSRM
Electric Fields, Charge: EFM, KPFM
Surface Potential / Workfunction: KPFM
Impedance: sMIM
Carrier density: SCM, SSRM, sMIM
Piezoelectric properties: PFM
Other: Scanning Gate, Pyro-Electric AFM, Photoconductive AFM,…
Bruker Webinar
© ©
Electrical Property Measurements with AFM
3/29/2018 4
Carbon NTs (4x2 µm)
Height
TUNA Current
InP nanowire (2x1 µm)
KPFM Potential
Height
Si DMOSFET (1x0.7 µm)
SCM dC/dV Height
Capacitor references (60x40 µm)
sMIM Capacitance Height
Pt nanoparticles in solution
Height
TUNA Current
SECM Current
Bruker Webinar
© ©
Imaging & Spectroscopy
3/29/2018 5
Height (nm) Current (pA) I-V Spectra
+
+ +
+
+
+ +
+
Tunneling AFM (TUNA) on a carpet of ‘standing’ carbon nanotubes (1x1 µm scan)
Bruker Webinar
© ©
Expand the Capability on 3 levels:
• Capture electrical spectra in every pixel
• Correlate electrical & mechanical properties
• Eliminate contact mode limitations, and expand to soft & fragile samples
3/29/2018 6 Bruker Webinar
© ©
Expand the Capability on 3 levels:
• Capture electrical spectra in every pixel
• Correlate electrical & mechanical properties
• Eliminate contact mode limitations, and expand to soft & fragile samples
3/29/2018 7
PeakForce Tapping
Height Adhesion Current
PeakForce TUNA on P3HT:CNT blends (700x700 nm scan)
Collaboration with Ph. Leclere, Uni Mons, Belgium See also: Nanoscale 4, no. 8 (2012), 2705.
Bruker Webinar
© ©
DataCubes
3/29/2018 8 Bruker Webinar
© ©
DataCubes Electrical Characterization Principle
• Fast Force Volume imaging: a force-distance spectrum in every pixel
• Insert a ‘hold segment’ (= ‘dwell time’) and perform an electrical measurement during the hold segment: electrical spectrum in every pixel
3/29/2018 9
DC Sample
Voltage
Electrical Channel
Z Force
Bruker Webinar
© ©
DCUBE-TUNA (Tunneling AFM) on Maghemite (γ-Fe2O3) • Force-distance & I-V spectrum in every
pixel (110 ms/pixel)
• TUNA current ‘slices’ shown as movie
3/29/2018 10
(movie)
Bruker Webinar
© ©
DCUBE-TUNA (Tunneling AFM) on Maghemite (γ-Fe2O3) • The datacube can be analyzed as current ‘slice’ data
• The datacube can be analyzed as I-V spectra
3/29/2018 11 Bruker Webinar
© ©
DataCubes Electrical Characterization Principle
3/29/2018 12
MECHANICAL
Force Volume DCUBE-TUNA DCUBE-SSRM DCUBE-SCM DCUBE-sMIM DCUBE-PFM
Ramp
ParameterDistance VDC VDC
VDC
VAC
fAC Phase
VDC
VAC
fAC Phase
VDC
VAC
fAC Phase
Output
Channel
Force
→ Stiffness
→ Adhesion
→ Modulus
Current log(Resistance)dC/dV Amplitude
dC/dV Phase
dC/dV Amplitude
dC/dV Phase
sMIM-C
sMIM-R
PFM Amplitude
PFM Phase
Example
Spectra
ELECTRICAL
Bruker Webinar
© ©
Capture electrical spectra in every pixel
3/29/2018 13
More information than other electrical AFM modes
Access previously inaccessible material properties and device data
Bruker Webinar
© ©
DCUBE-TUNA (Tunneling AFM) on Maghemite (γ-Fe2O3)
3/29/2018 14
𝑉𝑏+ = −ln(𝑎)
𝑏 > 0
Ohmic
No Conduction
• Using Matlab export/import functions, one can perform custom analysis: Here we fit all I-V spectra to extract potential barriers:
• Data processing by N. Chevalier & D. Mariolle at Uni. Grenoble Alpes, CEA, LETI
𝑦 = 𝑎𝑒𝑏𝑥 + 𝑐𝑒𝑑𝑥
(movie)
Bruker Webinar
© ©
DCUBE-SCM (Scanning Capacitance Microscopy) on SRAM Transistors
3/29/2018 15
• Sample voltage ramp from -2V to 2V
• 128x128 pixels, 2x2 µm scan
• 100 ms/pixel (27 min/cube)
• Data courtesy: N. Chevalier & D. Mariolle at Uni. Grenoble Alpes, CEA, LETI, France
-1.6V -1.2V -0.8V -0.4V
p n p p n p
dC/dV Amplitude
(movie)
Bruker Webinar
© ©
DCUBE-SCM (Scanning Capacitance Microscopy) on SRAM Transistors
• Sample voltage (VDC) ramp from -2V to 2V in every pixel
• Slices through the datacube show how the pnp junction profile changes with VDC
• Data courtesy: N. Chevalier & D. Mariolle at Uni. Grenoble Alpes, CEA, LETI, France
3/29/2018 16
p n p
p n p
X
Y
Y
VDC VDC
slice at fixed VDC slice at fixed Y position
dC/dV Amplitude DataCube
Bruker Webinar
© ©
DCUBE-sMIM (Microwave Impedance Microscopy) on Doped Si Device
3/29/2018 17
sMIM-C dC/dV Amplitude dC/dV Phase
• C-V and dC/dV-V spectra (-2V to +2V) in every pixel
-2.0V -1.5V -1.0V -0.5V 0.0V 0.5V 1.0V 1.5V 2.0V
Bruker Webinar
© ©
DCUBE-sMIM (Microwave Impedance Microscopy) on Si with staircase carrier profile
3/29/2018 18
• Sample voltage ramp from -2V to 2V in every pixel results in C-V spectra
• Sample source: Infineon Munich, DOI: 10.1016/j.microrel.2014.07.024
-1V
+1V
sMIM-R vs. time
sMIM-C vs. time
p-type n-type
+ +
+ +
Bruker Webinar
© ©
Practical Aspect: Speed?
3/29/2018 19
20 ms 100 ms 200 ms
64x64 1.4 6.8 13.7
128x128 5.5 27.3 54.6
256x256 21.8 109.2 218.5
Time per pixel
Pixels
Time per Image (min)
200 ms
100 ms
50 ms
25 ms
12 ms
sMIM C-V spectra on Si sample, collected at different speeds
Typ. time (ms)
Force-Distance Spectrum 10-100
Electrical spectrum 10-100
Total 20-200
Mode Bandwidth (kHz)
TUNA 15
sMIM 300
SCM 1-10
PFM 1-10
*fAC and LIA BW dependent
Bruker Webinar
© ©
DCUBE-PFM (Piezoresponse Force Microscopy) on BFO
3/29/2018 20
Amplitude
Phase
• PFM Amplitude and PFM Phase data slices
• Domains switch as voltage is increased. Different domains switch at different voltages
-6V -5V -4V -3V -2V -1V 0V
Bruker Webinar
© ©
DCUBE-PFM (Piezoresponse Force Microscopy) on BFO
• Amplitude spectra along one line are shown
• The images represent the PFM amplitude & phase vs. voltage along the line
3/29/2018 21
Sample
Bias
(V)
X
X
0
-1
-2
-3
-4
-5
-6
0
-1
-2
-3
-4
-5
-6
Bruker Webinar
© ©
Correlate electrical & mechanical properties
3/29/2018 22 Bruker Webinar
© ©
DCUBE-TUNA (Tunneling AFM) on Battery Cathode
3/29/2018 23
• Modulus, Adhesion, Stiffness & conductivity from -4V to +4V
• The data allow one to identify all elements (Li metal oxide, binder & carbon nanoparticles) and study differences between different metal oxide grains
-3.5V -2.5V -1.5V -0.5V +0.25V
+1V +1.75V +2.5V +3.25V +4V
Carbon black
Li metal-oxide
Polymer binder
Bruker Webinar
© ©
DCUBE-TUNA (Tunneling AFM) on Battery Cathode
3/29/2018 24
-500
-100
50
200
• Modulus, Adhesion, Stiffness & conductivity from -4V to +4V
• All I-V spectra in selected area displayed
+3V -3V
Bruker Webinar
© ©
DCUBE-sMIM (Microwave Impedance Microscopy) on Maghemite (γ-Fe2O3)
3/29/2018 25
• During a short hold segment, the DC bias was kept constant (no spectra)
• Mechanical properties (Adhesion shown) acquired simultaneously
• sMIM-C vs. time spectra shown for 5 positions
sMIM-C sMIM-R
Bruker Webinar
© ©
DCUBE-CR-PFM (Contact Resonance PFM) on LiTaO3
3/29/2018 26
(movie)
Bruker Webinar
© ©
Eliminate contact mode limitations
3/29/2018 27
Longer tip lifetime
Characterize soft & fragile samples
Better spatial resolution
Bruker Webinar
© ©
DCUBE-TUNA (Tunneling AFM) on Battery Cathode
3/29/2018 28
-4.0V -3.0V -1.0V
+1V +2.0V +3.0V +4.0V
Bruker Webinar
© ©
Peakforce-TUNA (Tunneling AFM) on P3HT Organic conductive nanowires
3/29/2018 29
• +3V sample voltage, 3x3 µm scan
Height (nm) Adhesion (nN) Current (pA)
Bruker Webinar
© ©
Summary
Combining Fast Force Volume imaging with Electrical modes generates Datacubes – enhancing the capabilities of conventional electrical AFM modes:
• Capture electrical spectra in every pixel
• Correlate electrical & mechanical properties
• Eliminate contact mode limitations & expand to soft & fragile samples
3/29/2018 30
Height Modulus Current
(movie)
Bruker Webinar
©
© Copyright Bruker Corporation. All rights reserved.
www.bruker.com
© Copyright Bruker Corporation. All rights reserved.