(Microsoft PowerPoint - \351coleaNW_ayari2.ppt) - IEMN
(Microsoft PowerPoint - \351coleaNW_ayari2.ppt) - IEMN
(Microsoft PowerPoint - \351coleaNW_ayari2.ppt) - IEMN
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
Introduction to nano-electromechanical<br />
systems<br />
Anthony Ayari, Pascal Vincent, Sorin Perisanu, May<br />
Choueib, Vincent Gouttenoire, Steve Purcell<br />
Laboratoire de Physique de la Matière Condensée et<br />
Nanostructures, Université Lyon 1<br />
Mikhael Bechelany, Arnaud Brioude,<br />
David Cornu<br />
Laboratoire de Multimatériaux et Interfaces,<br />
Université Lyon 1
Outline<br />
1)NEMS<br />
definition<br />
materials<br />
scaling<br />
experimental method<br />
2)New effects in nanomechanics<br />
oscillator<br />
non linear effect, hysteresis<br />
frequency tuning<br />
Casimir forces<br />
quantum/ thermal regime<br />
3)state of the art<br />
-performances : frequency range, quality factor<br />
-nanobalance<br />
-Self oscillations in nanomechanics
Electro Mechanical Systems<br />
What is is ? How it works ?<br />
Signal IN(ω)<br />
x<br />
External Perturbation<br />
Signal OUT(ω)
At the micron scale<br />
Detector<br />
Accelerometer for airbag<br />
Mechanical springs<br />
Width 50nm<br />
1 µm<br />
Electrostatic combs<br />
Gap width 150nm<br />
Actuator<br />
Digital micromirror device in video projector
materials<br />
Si, SiN, GaAs<br />
standard in<br />
microelectronic<br />
Nanowire Pt, SiC<br />
AlN, ZnO piezo-<br />
electric<br />
carbone nanotubes<br />
300 nm<br />
Pt<br />
SiN<br />
J.A.P. 99,124304(2006)<br />
A.P.L. 83,1240(2003)
Scaling<br />
Mass (< 10 -15<br />
g) m eff ~ L 3<br />
Resonant frequency (10 MHz à 1GHz) ~ L -1<br />
Amplitude (
Nano Electro Mechanical Systems<br />
ISSUES :<br />
Low OUTPUT signal<br />
Low Q factor<br />
Crosstalk<br />
Signal IN(ω)<br />
x<br />
External Perturbation<br />
CROSS TALK<br />
Signal OUT(ω)
Detection/actuation<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
Magnetomotive<br />
Optical : laser<br />
Capacitive<br />
SEM<br />
Field emission<br />
AFM<br />
STM<br />
F=I*L^B<br />
Laplace Force<br />
Need high magnetic field
Optical coupling<br />
2µm<br />
Need flat surface, good reflexion<br />
APL 86 193114 (2005)
capacitive<br />
Low signal and large band pass<br />
Impedance mismatch with 50 Ω
SEM<br />
SiC<br />
Nanowire<br />
rest fundamental harmonics<br />
PRB 66 073406 (2002)
Field emission<br />
Experimental set up, out of the resonance<br />
Nanowire<br />
Tungsten tip<br />
Anode<br />
V A<br />
-<br />
+<br />
Anode<br />
∼ V s<br />
e -
Field emission<br />
Experimental set up at the resonance<br />
Nanowire<br />
Tungstene tip<br />
Anode<br />
V A<br />
-<br />
+<br />
Anode<br />
∼ V s<br />
e -<br />
Amplification of the vibration amplitude by<br />
projection
Why nano ?<br />
Lower size<br />
Lower power consumption<br />
Faster mechanically and thermally<br />
Mass sensing : single molecule/atom, nano<br />
bio<br />
New forces/phenomena/paradigm
What’s new?<br />
Non-linearity<br />
Frequency tuning<br />
Casimir force surface
Non-linear<br />
effects<br />
Amplitude<br />
∆f<br />
Fréquence<br />
Lorentzien shape,<br />
quality factor :<br />
Q=f/<br />
f/∆f<br />
ẍ+ω 0 ẋ/Q+ /Q+ω 2 0 x =F(t)/m eff
Non-linear<br />
effects<br />
Amplitude<br />
Frequency (Hz)<br />
Hysteresis, , jumps,<br />
memory<br />
ẍ+ω 0 ẋ/Q+ /Q+ω 2 0 x +ax 3 + … =F(t)/m eff
Non-linear<br />
effects<br />
Amplitude<br />
Frequency (Hz)<br />
Need to reduce<br />
excitation<br />
Critical amplitude:
Role of Electric Field<br />
Electrostatiques Forces :<br />
– T L ≈ (ε 0 /2).πr 2 . F 2 ≡ γ 2 β 2 V 2 APP<br />
Tuning like music intrument
Frequency tuning<br />
Nanofil<br />
4.0<br />
MWNT<br />
Pointe en tungstène<br />
Anode<br />
3.0<br />
V A<br />
-<br />
+<br />
Anode<br />
e -<br />
2.0<br />
1.0<br />
∼ V s<br />
0.0<br />
400 500 600 700 800 900 1000<br />
Tension (Volt)<br />
PRL 89, 276103 (2002)<br />
linear variation of the resonant<br />
frequency with tension<br />
tunable resonator
Casimir forces<br />
PRL 87, 211801 (2001)<br />
Science 291, 1941 (2001)<br />
Quantum fluctuations of vacuum<br />
H=ħω n (p+1/2) with p=0<br />
Confinement effect ω n inside < outside
Thermal vibration<br />
E thermal =k B T ⇒<br />
∆x thermal = L -0.5<br />
Observed in CNTs<br />
dominates excitation<br />
for low L (∆x(<br />
lin ~ L)<br />
P.R.B. 58,14013(1998)<br />
Nature 381, 678 (1996)<br />
Nanoletters 3,1577(2003)
Quantum limit<br />
H=½mv<br />
2 + ½kx<br />
2 ⇒ H=hν(a<br />
+ a+1/2)
Macroscopic quantum oscillator<br />
NEMS coupled to an SET<br />
∆x quantique = L -1 , n=58<br />
Resolution ∆x x = 114 fm<br />
1GHz=50 mK<br />
Quantum computing, Heisenberg<br />
science 304,74 (2004)<br />
PRL 94 030402 (2005)<br />
, Heisenberg inequality
Performances<br />
Damping<br />
Mass sensing<br />
Self-oscillation
Quality factor<br />
Log(Q)=.3*log(vol(mm 3 ))+6
Nanobalance<br />
nano letters 6, 583 (2006)<br />
Résolution<br />
δm=2m* m=2m*δν/ν=2m/Q<br />
⇒ 7 zg (10 -21<br />
g) soit 30 atomes
GHz NEMS<br />
Nature 421,496 (2003)<br />
New Journal of Physics 7 (2005) 247
Self-oscillations<br />
What is self oscillation?<br />
– Self oscillator: constant input generates periodic<br />
output<br />
=Driven oscillator: periodic input generates periodic<br />
output<br />
Observed in many fields:<br />
– Oscillating chemical reaction<br />
– heart beat<br />
– Rayleigh - Bénard<br />
thermal convection<br />
– Gunn diode: negative differential resistance<br />
electrical device<br />
Is it possible in NEMS ?
Self-oscillation in UHV<br />
<br />
<br />
Widening of the field<br />
emission pattern without<br />
AC signal<br />
Jump and hysteresis in IV<br />
curve
SEM Experiments<br />
Ayari et al., Nano Letters Vol.7, Issue 8, 2252, (2007)
Self-oscillations in SEM
Why did it work ?<br />
V<br />
R, k<br />
C, k Y , m eff , γ<br />
es<br />
x<br />
U, I FN
Why did it work ?<br />
V<br />
C, k R, k<br />
es<br />
Y , m eff , γ<br />
U, I<br />
x<br />
FN<br />
⇒ Similar to the physics of the garden<br />
hose
Why did it work ?<br />
Mechanical equation<br />
&& x<br />
2<br />
+ γ x&<br />
+ ( ω + pU ) x =<br />
0<br />
2<br />
0<br />
k Y m eff , γ k es (U)<br />
x
Why did it work ?<br />
<br />
Electrical equation<br />
d<br />
dt<br />
VDC −U<br />
( CU ) = − I<br />
FN<br />
,<br />
R<br />
( U x)<br />
Wire apex<br />
C(x)<br />
V<br />
R I FN (U, x)<br />
tip<br />
U
Why did it work ?<br />
Mechanical equation<br />
&& x<br />
Electrical equation<br />
d<br />
dt<br />
2<br />
+ γ x&<br />
+ ( ω + pU ) x =<br />
0<br />
VDC −U<br />
( CU ) = − I<br />
FN<br />
,<br />
R<br />
2<br />
0<br />
( U x)<br />
huge R<br />
Coupled equations<br />
Low damping (Perisanu et al. APL 2007, 90, 043113)<br />
x dependence in FN current<br />
Non linear terms
Numerical simulations and semianalytical<br />
calculation<br />
•Good qualitative agreement<br />
•hysteresis
Summary<br />
First observation of self–oscillation in a fully<br />
electrical NEMS<br />
DC-AC converter 50 %<br />
Nano AC generator<br />
Solution against cross talk
Conclusion<br />
NEMS : mechanical oscillators at the<br />
nanoscale<br />
Difficult to actuate and detect, high<br />
damping<br />
Applications in mass sensing, high<br />
frequency communication