Download Novel characterization technique: transport-STM

Structural and electronic characterization
of single-wall nanotube DNA hybrids
Lolita Rotkina, Stacy E. Snyder,
Slava V. Rotkin
Physics Department &
Center for Advanced Materials and Nanotechnology
Lehigh University
Tight-binding results
Self-consistent solution for the
charge density of semiconductor
[7,0] zigzag NT under DNA wrap
perturbation
Tight-binding results
Self-consistent solution for the
charge density of semiconductor
[7,0] zigzag NT under DNA wrap
perturbation
Polarization interaction:
for [7,0] NT and {6:1 | 4e} wrap the
cohesion energy due to the NT pi-e-
system polarization de ~ 0.47 eV/b.p.
interaction with the
image charge
overestimates C.E.
image charge for
semiconductor
Randomize DNA potential
100
80
60
40
20
0
0
5
10
15
20
25
Scaling results: Gaps in S- M-NTs
Scaling results: Gaps in S- M-NTs
Eg
2
20
-0.1
-0.2
-0.3
-0.4
40
60
80
100
120
140
Q2
Scaling results: Gaps in S- M-NTs
Novel STM-TEM facility
STM-TEM Nanofactory stage
To be installed inside JEOL 2200FS FEG-TEM
STM-TEM Nanofactory stage by Gatan
All images courtesy Gatan (unless author specified)
STM-TEM Nanofactory stage
Nanofactory controller
Side entry TEM sample
holder is equipped with a
full power STM
TEM-STM Stage
Computerized control
STM-TEM Nanofactory stage
Inertial slider-driven
coarse movement
Piezo-driven fine
movement
Interchangeable
sample holders
STM-TEM Nanofactory stage
< 1 mm – 1 mm
Sample holder
Inertial slider-driven
coarse movement
Piezo-driven fine
movement
< 0,1 Å – 2,5 mm
< 1 Å – 20 mm
In-situ Characterization STM -TEM
Si whiskers
Characterization (1)
Novel characterization technique: transportSTM-TEM combined tool
sample holder
contact pads
and mirror pads
membrane
spring ring
bottom view
Characterization (1)
Novel characterization technique: transportSTM-TEM combined tool
Characterization (1)
Novel characterization technique: transportSTM-TEM combined tool
Characterization (1)
Novel characterization technique: transportSTM-TEM combined tool
5 nm
20 nm
HR-TEM Cs aberration corrected
dedicated TEM/STEM (Kiely)
20 nm
Charge Trapping and
Memory Effects
Characterization (2)
Liquid crystal
placement for
FET/sensor
fabrication
(Jagota)
Novel femtosecond characterization
technique: fast photoelectric response
(Biaggio, COT, Lehigh)
Characterization (2)
Keithley Semiconductor Characterization Station 4200 with pA preamplifier.
Custom made low-current low-noise photo-electric probe station (Biaggio, Rotkin)
Photoresponse of Polymer-NT FET
sample 3
Id/Vd, mA/V
1.18
1.17
-1.5 V
-1.0 V
1.16
-0.5 V
1.15
1.5 V
1.0 V
1.14
Vd = 0.5 V
0
25
50
75
100
125
150
t, sec
Photoconductance Id/Vd vs time of the light pulse.
Amplitude is independent of Vd (and Vg)
175
Photoresponse of Polymer-NT FET
sample 3
Qg, nC
Ig /Vg, nA/V
5
7
6
4
5
3
4
3
2
2
1
1
t, sec
0
50
100
150
Total photocurrent pulse = trapped charge
200
0
Photoresponse of Polymer-NT FET
Id/Vd / (Idmax/Vdmax), a.u.
sample 3
sample 6
1.03
1.025
1.02
1.015
1.01
1.005
1
20
40
60
80
100
120
140
t, sec
Photoresponse is similar for two different polymer substrates.
Hysteresis in SWNT-array Transistors
Experiment: Laminated Device, CVD Tubes
0
-20
-40
ID (mA)
-60
-80
-100
-120
VD= -20V
-140
-160
-30
decreasing scan rate
decreasing scan rate
-20
-10
0
10
20
30
VG (volts)
Courtesy J.Rogers
Robert-Peillard, Rotkin, 2005
Single NT FET
Physics of current
hysteresis in NT FETs:
• Gate voltage controls the
charge of the channel
source @ ground
drain @ Vd
1D channel
• In addition to the charge
stored in the gate (gate
capacitance), strong
electric field generates
charges at the interfaces
(add.capacitances)
• This shifts the threshold
voltage (and changes
mobility)
• The field is selfconsistent with the charge
insulator
gate @ Vg