lukas worschechlukas worschech technische physik ... summer school 2011...model for explanation...
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Energy harvesting in nanoelectronic devices Lukas WorschechLukas Worschech
Technische Physik, Universität Würzburg, Germany
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Energy harvesting with nanoelectronics
• Energy harvesting: Energy provider+Transducer+Rectifier
• Nonlinearities in nanoelectronics: Quantum effects, reduced screening, many devices, bits per volumeUlt i i t i d i it S ll i l t• Ultra-miniaturized circuits: Small signal-to-noise ratios (SNR) & feedback between different devices are unavoidable
• Is it possible to exploit ambient noise and• Is it possible to exploit ambient noise and feedback action for electronic applications
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Outline• Nanoelectronic semiconductor electronic
devices– Technologygy– Nonlinear nanoelectronic transport
• Magnetic field asymmetry in quantum wire• Magnetic field asymmetry in quantum wire• SR in a YBS as B field sensor• Y-branch as logic gate and GHz rectifier• Logic stochastic resonance in RTDsg
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
semiconductors
• Electronics: frequencies Hz – THz• Optoelectronics: wavelengths 0.2 – 100 µmp g µ
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Some electronic devices
• Transistors and memories
bitlinewordline
bitline
FET
today FLASHcapacitorDRAM
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Electrostatics of FETs with nearby charges
g CQV
gq
Wq
g
Wq
gqWTg
CC
CC
CVVV
1)(
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Heterostructures: Band gap engineering
Combination of different semiconductors with atomic precision
Growth techniques: e g Molecular beam epitaxy (MBE) Growth techniques: e.g. Molecular beam epitaxy (MBE)
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
GaAs/AlGaAs HEMT
Modulation-doped GaAs/AlGaAs heterostruktur (HEMT)
Mean free path: ~10µms @ 4,2K / 50 – 200nm @ RT
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Structuring
Top-down route: lithography, etching,…
Bottom-up route: self-assembly, seeded growth,…p y, g ,
Different geometries: wires, dots, rings, splitters…Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Characteristic lengths• De Broglie wavelength: phldeBroglie /
• Fermi wavelength:FEEdeBroglieF ll |
kk • Mean free path: ek
me
ek
mpvlm
• Phase coherence length: mkThl 2/
L
a)
a) Diffusive
W
b)
)
)b) Coherentc) Ballistic
Wc)
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Linear mesoscopic transportp p
• Conductance quantization in 1D wires1D wires
III LRRLT
22
TffEEdEhe
eVf
RL
Dv D
**/1*2
)(~ 1
eV )(~
TheVIG
22/
• Multi-terminal conductor:
h
Landauer-Büttiker formula
jijii TeI 2
jj
ijii Th
I
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
What is nano? A comparison: metals vs semiconductor
Metal:Gold film
H. Ohnishi et al., Nature 395, 780-782 (1998).
n = 2.3 x 1015/cm2
lF = 0.52 nm, EF=5.5 eVl ~ 1 10 nmlm ~ 1-10 nml~ 1-100 m
Semiconductor:2 dimensional electron gas (2DEG)
11 2n = 3.0 x 1011/cm2
lF = 46 nm, EF= 11 meVlm ~ 1-100 m T < 4 Km l~ 1-100 m
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Quantum wire
• Electron wave propagation: each occupied subband t ib t ith 2 2/h t th d t contributes with 2e2/h to the conductance
conductance quantization7
8
3
4
5
6
G (2
e2 /h)
0
1
2
3
0,5 1,0 1,5-1
Vg (V)
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Outline• Nanoelectronic semiconductor electronic
devices– Technologygy– Nonlinear nanoelectronic transport
• Magnetic field asymmetry in quantum wire• Magnetic field asymmetry in quantum wire• SR in a YBS as B field sensor• Y-branch as logic gate and GHz rectifier• Logic stochastic resonance in RTDsg
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Asymmetric scattering
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Deterministic asymmetry
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Outline• Nanoelectronic semiconductor electronic
devices– Technologygy– Nonlinear nanoelectronic transport
• Magnetic field asymmetry in quantum wire• Magnetic field asymmetry in quantum wire• SR in a YBS as B field sensor• Y-branch as logic gate and GHz rectifier• Logic stochastic resonance in RTDsg
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Stochastic resonance
SR k i l b• SR: weak signals can be amplified by fluctuations
• SR conditionsSR conditions– non-linear system (threshold)– Subthreshold signal– noise
• SR was introduced as model for explanation ofmodel for explanation of the periodic ocurrence of ice ages: Benzi, Parisi, SSutera, Vulpiani
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Dynamical gate operation in a YBS
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Bistable selfswitching:Bistable selfswitching: depends on the bias voltage
YBS as amplifier and rectier logic operation
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
SR: Working principle
• self-gating leads to a bistableg gtransfer characteristic• the input and the working point
lt t t bi t blvoltages were set to bistableswitching controlled by noise • all measurements @ 20Kall measurements @ 20K
)sin()( 0, tVVtV ggg Input signal:
ggg
Weak periodic signal:
mVV 31 mVVg 3.1
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
SR: Signal traces
f = 0.1 Hz
f = 1 Hz
f = 1.8 Hz
At f = 1 Hz the noise dynamics follow directly the frequency of the external input forcing and a maximum synchronization is found.
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Recording SR: Residence Time
For the unmodulated system with f = 0 Hz the residence time distribution decays exponentially with the inverse of thetime distribution decays exponentially with the inverse of the Kramer‘s rate
0.2
)exp()(,K
HL TTTN
(s)
KT0.1
NL
(T)
From fitting:
0 1 2 3 4 50.0
T (s)sTK )044.0502.0(
g
T (s)
KTT 2Time matching condition of SR: KTT 2Time matching condition of SR:
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Recording SR: Residence Time
0.20.2f = 0.6 Hzf = 0.1 Hz• For f < fSR the residence time
0 1 2 30.0
0.1
0 2 4 60.0
0.1 distribution is strongly controlled by the noise
0.40.4
0 1 2 3T (s)
0 2 4 6
f = 2.4 Hzf = 1.8 Hz
T (s)
0.0
0.2
0.0
0.2 • For f > fSR odd multiples of the periodic forcing Tω occur:
0 1 2 30.0
T (s)0 1 2 3
0.0T (s)2/)12( TnTn
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Recording SR: Residence Time
At the optimum frequency f = 1 Hz the residence time f fdistribution is almost perfectly restricted to the first peak.
0.4
(s)
0.2
NL
(T)
0 1 2 30.0
T (s)T (s)
The time scale condition of SR is fulfilled by tuning solely the frequency of the periodic forcingfrequency of the periodic forcing.
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
SR: Residence Time Distribution
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Application: Magnetic field sensor
• Set the detector inSet the detector in the strongly noise activated regime• Magnetic field applied perpendicular to the motion ofto the motion of electrons either in or out of the plane
LHn
TT,1
p
ii
iLH
LHLH T
nT
1,
,,
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Application: Magnetic field sensor
0.700.75
Vbr,th • V decreases down
0 00.550.600.65
Vbarrier (V) -0,520 -0 514r
(V)
• Vbr decreases down to a magnetic field threshold Bth
• Transitions between
0 350.400.450.50
B
0,514 -0,508 -0,502 -0,496 -0,490
Vb
B
the two states occur between ∆B
1 5
0.0 0.5 1.0 1.5 2.0 2.5 3.00.35 B ,
B (T)
Bth
0.62
0.64
0 5
1.0
1.5
r,th
(V)
Bth
(T)The magnetic-field induced
switching is associated with
-0.52 -0.51 -0.50 -0.49
0.600.0
0.5V
br
B
a scattering asymmetry at the boundaries
Vbarrier (V)
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Application: Magnetic field sensor
3 0
s)2.53.0
ime
(s
1.52.0 TH TL
ence
ti
0 51.0
resi
de
0.00.5
mea
n r
0 10 20 30 40 50 60
m
B (mT)B (mT)
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Application: Magnetic field sensor
1.5 Measurement
0 51.01.5 Measurement
Simulation
)
Linear Fit• Output is a linear function of B around ∆T = 0 s
0 50.00.5
T
(s)
• Target signal independent iti it
-1.0-0.5 sensitivity
0 10 20 30 40 50 60-1.5
B ( T)
cBTBT 0)(B (mT)
cBTBS
)(B
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Outline• Nanoelectronic semiconductor electronic
devices– Technologygy– Nonlinear nanoelectronic transport
• Magnetic field asymmetry in quantum wire• Magnetic field asymmetry in quantum wire• SR in a YBS as B field sensor• Y-branch as logic gate and GHz rectifier• Logic stochastic resonance in RTDsg
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Y-branch as ballistic rectificationRectification due to junctions:
• pn-junction• pn junction
• Metal-semiconductor junction
Y-branch junction: no geometrical asymmetry!
V (Y)r
0 05
0,00
V (X)l V (X AND Y)s-0,10
-0,05
Vs (V
)
V r
V s-0,15
Experiment Theory:
diffusive ballistic
V l-0,4 -0,2 0,0 0,2 0,4
Vxy (V)
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Y-branch as ballistic rectification
V Vdiffusive Transport
Vl Vr
-0,05
0,00
-0,10
Vs (V
)
V s
Quasi-ballistic Transport
-0,4 0,0 0,4
-0,15 diffusive ballistic
, , ,Vxy (V)
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
YBS nonlinearity used for a compact adder
Half-Adder: binary addition with carry bit
h bl
y y
S h
X Y Z C
Truth table
X & = AND
Scheme
X Y Z C
H H L H
&XY C
= XOR=
H L H L
L H H L
Z=
L L L L> 10 FETs + i t tinterconnects
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Nanoelectronic Half-Adder
• planar Half-Adder is basedon ballistic Y-junctionson ballistic Y junctions
• Inputs: x and y x g
• Outputs: c and z
Working point: s
lv sr• Working point: s
• Control: v
yc z
100 nm
L. Worschech et al., Appl. Phys. Lett. 83, 2462 (2003)
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
ModelModel
control of Vz via Vc: gate
a) Injection of electronsc zc
sl r
b) Gating
N t l t !
c zz
VVVs
R
c
No external gate!
Self induced switching
VzVc Vdg
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
0.1s
gate
l r
0.0 Vs = 0.1 V
Vz (V
)c zz
VVVs
R=10M
c
0 1 V
-0.1Vd = 0.1 V
VzVc Vd
-0.1 V -0.3 V -0.2 V
-0.4 -0.2 0.0 0.2 0.4Vc (V)
• Self switching N-shaped Vz (Vc)-characteristics
• Definition of the working point via Vsg p s
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
y c zy
x
Vx
c
s
gate
l r
0 10Vs = -0.3 V
VZ
(L H)(H H)(H L)
VC y c zy z
VzVc Vd
VsVy
R
c
0.05
0.10
V)
Z
0.1C
V)
d
0.00
Vz (
V
0.0
Vou
t (V
-0.05• Push-Pull-Mode:Vx + Vy= 0.3 V
• Push-Pull-Mode:Vx + Vy= 0.3 V
1 50 0 75 0 00 0 75 1 50
-0.1
-0.6 -0.3 0.0 0.3Vc (V)
• Rectification: Vc < (Vx + Vy)/2 • Self induced Switching: M shaped V characteristic
• Rectification: Vc < (Vx + Vy)/2 • Self induced Switching: M shaped V characteristic
-1.50-0.75 0.00 0.75 1.50Vx -Vy (V)
M-shaped Vz-characteristicM-shaped Vz-characteristic
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
V g Demonstration of logic function at RT:
T = 4.2 K T = 50 K T = 300 Ky c zy
x
z
Vx
Vs
c
s
g
l r
e o s a o o og c u c o a
0,00
0,10
z (V
)
y c zy zVz
Vc
V
Vy
R
c
-0,10
Vz
0 00
Vd
-0,50
-0,25
0,00
Vc (
V) X Y Z C
H H L HH L H L
(LL)
(HL)
(LH
)(H
H)
(HH
)(L
H)
(HL)
(LL)
(HH
)(L
H)
(HL)
(LL)
-0,75
H L H LL H H LL L L L Logic inputs (XY)L L L L
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Dynamic properties of rectification
0,0
room temperature
V)
-0,5
VS (
V
1 1 1 AND Address Level
)
-1,0-1
01 -1-1 1
-1 -1
VS (
V)
-1,0 -0,5 0,0 0,5 1,0
V (V)
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Microwave rectification: energy harvesting
2VV 2VcVs f
assuming3T ballistic cavity
)2
sin( 1~ tfVV
with
yA. N. Jordan, Markus Büttiker, PRB 2009 2
)2cos( 122 tfVcVcV ec 1~ )2
cos(22 ~~ tVVVs
F
c2
~
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
High Frequency SetupHigh Frequency Setup
S-Parameter
2at detectedpower microwaveS1 into injectedpower microwave
de ec edpowec ow ve21 S
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Frequency doubling
-70 f2 = 100 MHz
Bm)Injection Detection
-70
-90
-80P 2 (dB
IS
V = 0S
IS
V = 0S
j
-80
P 2 (dB
m) -1,0 -0,5 0,0
V (V)
V o V-V /2o V o V-V /2o
f2 = 2f1f1
P
-902nd harmonic
0 5 10 15 20
2nd harmonic
f2 (GHz)f
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Microwave generates a DC current
10-3
10-2
T = 300 Kf = 10 GHz0,4
f1 = 10 GHz) 10-5
10-4
VC = -1 V
f = 10 GHz
)
0,2 10 dBm 8 dBm 6 dBm no microwave
I S (A
10-7
10-6
I S(A)
0,0 10-9
10-8
-0,1 0,0 0,1
V (V)-5 0 5 10 15
10-10VC = 0.3 V
P(dBm)V (V) P(dBm)
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Outline• Nanoelectronic semiconductor electronic
devices– Technologygy– Nonlinear nanoelectronic transport
• Magnetic field asymmetry in quantum wire• Magnetic field asymmetry in quantum wire• SR in a YBS as B field sensor• Y-branch as logic gate and GHz rectifier• Logic stochastic resonance in RTDsg
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Resonant-tunneling diode
fast operation TH● fast operation ~THz● negative differential resistance
ballistic operation at room temperature● ballistic operation at room temperatureLukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
RTD operation
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Logic operation with RTD mesas
200
050
100150200
V (m
V) split RTDdiameter: 600nm
0,00 0,25 0,50 0,75 1,00 1,25 1,50Vdc (V)
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
No thermal transconductance limit ultra small switching voltagesNo thermal transconductance limit ultra small switching voltages
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Logic RTD gates
Vac = 23 mV Vac = 25 mVVac = 24.5 mV
V1 = V2 = 0 mV == Log. input I = I1+I2=0+0=0
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Logic RTD gates
Vac = 25 mV Vac = 26.5 mVVac = 26 mV
V1 = 0,2 V2 = 2,0 mV == Log. input I = I1+I2=1+0=0+1=1
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Logic RTD gates
Vac = 26.5 mV Vac = 29 mVVac = 27.5 mV
V1 = V2 = 2 mV == Log. input I = I1+I2=1+1=2
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Logic RTD gates
NOR
0 0 | 1NAND
0 0 | 10 0 | 11 0 | 00 1 | 0
0 0 | 11 0 | 10 1 | 1
1 1 | 0
transition from NOR to NAND opertation for
1 1 | 0
transition from NOR to NAND opertation for amplitude changes smaller than 1 mV
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Logic stochastic resonance
Murali, K. , Sinha, S. , Ditto, W. , Bulsara, A. Phys. Rev. Lett. 102, 104101 (2009).
Murali, K., Rajamohamed, I. , Sinha, S. , Ditto, W. , and Bulsara, A. , Appl. Phys. L tt 95 194102 (2009)Lett. 95, 194102 (2009).
L. W., F. Hartmann,T. Y. Kim,S. Höfling,M. Kamp A Forchel J Ahopelto 2I Neri AKamp,A. Forchel,J. Ahopelto,2I. Neri,A. Dari, L. Gammaitoni, APL 2010
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
RTD as light sensor and light-programmable LSR
120 P=0nW P=0.1 nWGaussian Fit
60
80
100
Cou
nts
Gaussian Fit
91 90 89 88 87 86 85 840
20
40
-91 -90 -89 -88 -87 -86 -85 -84<VS> (mV)
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
SummarySu a y
• Introduction into different nanoelectronicdevices
• Nonlinear transport: rectification, bistableswitching
• Noise-induced switching, logic stochastic resonanceRoutes for energy harvesting in nanoelectronics• Routes for energy harvesting in nanoelectronics
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
For important contributions many thanks to
Transport:F H t S K li S Gö f t A D i LF. Hartmann, S. Kremling, S. Göpfert, A. Dari, L. Gammaitoni
Technology:M. Emmerling, S. Kuhn, T. Steinl, G. Heller, M. Kamp
III-V samples:C. Schneider, S. Höfling, A. Forchel
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011
Acknowledgement
• Support via EU: SUBTLE & NANOPOWER
• Many thanks for your attention!Many thanks for your attention!
Lukas Worschech, NiPS summer school 2011, Perugia, 01.-05.08.2011