Title: A Three Terminal Carbon Nanotube Relay
1A Three TerminalCarbon Nanotube Relay
Experiment
- S. W. Lee (1,2)
- M. Sveningsson (2)
- Y. W. Park (1)
- E. E. B. Campbell (2)
- J. Kinaret (2)
- M. Jonsson (2)
Theory
1 School of Physics and Nano Systems
Institute-National Core Research Center,
Seoul National University, Seoul 151-747,
Korea 2 Department of Physics, Göteborg
University, SE-41296 Göteborg, Sweden
2Outline
- Motivation
- Fabrication method of CNT relay structure
- Electromechanical measurements
- (1) Contact mode
- (2) Non contact mode
- Summary and future prospect
3Motivation
- CNT based Nano electromechanical system (NEMS)
CNT based rotational actuator
Conductance changes according to strain
Nature 424, 408 (2003)
PRL 90, 156401 (2003)
Tunable CNT electromechanical oscillator
CNT tweezers
Science 286, 2148 (1999)
Nature 431, 284 (2004)
4- CNT based nano relay New NEMS
Kinaret et. al, APL 82, 1287 (2003)
5Equation of motion
Cantilever deflection
Electrostatic force
Van der Waals force
Short range interaction
Kinaret et. al, APL 82, 1287 (2003) first
theoretical modeling of nano relay
6Fabrication method ofCNT relay structure
(a)
(e)
(b)
(d)
(c)
10?m
AC
Acid free method to make suspended structure S.
W. Lee et. al Appl. Phys. A 78, 283 (2004)
7SEM images of CNT relay structures
8Relation between diameter and suspended length of
CNT
9Critical point dry after lift off process
Liquid effect due to surface tension of water
After critical point dry process
10Force-distance measurement of relay structure
10nN of mechanical force is necessary to push
CNT down to the drain electrode
S. W. Lee et al. Nano Lett. 4, 2027 (2004)
11Estimating electrostatic voltage to make 10nN of
force for dragging CNT
d
x
Approximation parallel plate capacitor
where C0 ?0A/d 10-18 F
Height from the substrate 80 nm
Voltage to make 10nN of dragging force 30V
12I-Vg characteristics of relay structures (contact
mode)
VSD500mV
contact
S. W. Lee et al. Nano Lett. 4, 2027 (2004)
13S. W. Lee et al. Nano Lett. 4, 2027 (2004)
14Theoretical calculation for non contact mode of
relay structure
M. Jonsson, lic. Thesis (2004)
15I-V characteristics of relay structures
(non-contact mode)
No hysteresis
Studied for shorter structures where contact with
the drain electrode cannot occur
Qualitative agreement with theory
Current modulation with gate voltage
M. Sveningsson, S. W. Lee, E. E. B. Campbell
16Summary Future Prospect
- Controllable arrays of 3-terminal CNT relay
structures were made using ac dielectrophoresis
method and E-beam lithography processes. - The force-distance measurement was done.? The
mechanical force to pull CNT down to the
substrate was estimated. - Electromechanical properties of relay structures
measured. - (both contact and non-contact mode were observed
from transport measurement) - High frequency measurement to observe resonance
of relay and switching time is on going
17Acknowledgements
- This work was supported by the Swedish Foundation
for Strategic Research (SSF CMOS integrated
carbon-based nanoelectromechanical systems) and
EC FP6 funding (contract no. FP6-2004-IST-003673,
CANEL). - The Korean co-authors were supported by a STINT
collaboration project between Göteborg University
and Seoul National University and the Nano
Systems Institute - National Core Research Center
(NSI-NCRC) program of KOSEF and BK21 of MOE, KOREA
18Critical point dryer (CPD 030, BAL-TEC Co.)
- Processes of critical point dry method
- After lift off with acetone, the sample was
transferred to an acetone filled critical point
dryer (CPD 030, BAL-TEC Co.) chamber. - The chamber was cooled down below 10?C. By
injecting liquid phase CO2 and discharging the
media in chamber for several times, CO2 was
substituted for acetone. - Then the temperature and pressure of chamber was
increased simultaneously up to critical point of
CO2 (T 31?C and P 73bar). - At this point the phase change from liquid to gas
was occurred without density change in the
chamber. - The drying process was completed when pressure
was decreased isothermally down to the
atmospheric.