Energy harvesting in nanoelectronic devices. Technische Physik, Universität Würzburg, Germany

Transcription

1 Energy harvesting in nanoelectronic devices Lukas Worschech Technische Physik, Universität Würzburg, Germany

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3 Energy harvesting with nanoelectronics Energy harvesting: Energy provider+transducer+rectifier Nonlinearities in nanoelectronics: Quantum effects, reduced screening, many devices, bits per volume Ultra-miniaturized i t i circuits: it Small signal-tonoise ratios (SNR) & feedback between different devices are unavoidable Is it possible to exploit ambient noise and feedback action for electronic applications

4 Outline Nanoelectronic semiconductor electronic devices Technology Nonlinear nanoelectronic transport 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 RTDs

5 semiconductors Electronics: frequencies Hz THz Optoelectronics: wavelengths µm

6 Some electronic devices Transistors and memories wordline bitline FET today capacitor DRAM FLASH

7 Electrostatics of FETs with nearby charges ( V g V T ) V W Q Vg Cgq CWq C 1 C C g Wq gq

8 Heterostructures: Band gap engineering Combination of different semiconductors with atomic precision Growth techniques: e.g. Molecular beam epitaxy (MBE)

9 GaAs/AlGaAs HEMT Modulation-doped GaAs/AlGaAs heterostruktur (HEMT) Mean free path: 4,2K / 50 RT

10 Structuring Top-down route: lithography, etching, Bottom-up route: self-assembly, seeded growth, Different geometries: wires, dots, rings, splitters

11 Characteristic lengths De Broglie wavelength: l debroglie h / p Fermi wavelength: l F l debroglie E E F p k k e k k Mean free path: l m v m e m e Phase coherence length: l h / 2mkT L a) Diffusive b) Coherent c) Ballistic a) b) c) W

12 Linear mesoscopic transport p p Conductance quantization in 1D wires 1D wires I I I L R R L T 2 2 T f f E E de h e ev f R L D v D * * *1/ 2 ) ( ~ 1 ev ) ( ~ T h e V I G 2 2 / Multi-terminal conductor: h Landauer-Büttiker formula j ij i i T e I 2 j j ij i i T h I

13 What is nano? A comparison: metals vs semiconductor H. Ohnishi et al., Nature 395, (1998). Metal: Gold film n = 2.3 x /cm 2 l F = 0.52 nm, E F =5.5 ev l m ~ nm l ~ m Semiconductor: 2 dimensional electron gas (2DEG) n = 3.0 x /cm 2 l F = 46 nm, E F = 11 mev l m ~ m T < 4 K l ~ m

14 Quantum wire Electron wave propagation: each occupied subband contributes with 2e 2 /h to the conductance 8 conductance quantization G (2e 2 /h) ,5 1,0 1,5 V g (V)

15 Outline Nanoelectronic semiconductor electronic devices Technology Nonlinear nanoelectronic transport 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 RTDs

16 Asymmetric scattering

17 Deterministic asymmetry

18 Outline Nanoelectronic semiconductor electronic devices Technology Nonlinear nanoelectronic transport 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 RTDs

19 Stochastic resonance SR: weak signals can be amplified by fluctuations SR conditions non-linear system (threshold) Subthreshold signal noise SR was introduced as model for explanation of the periodic ocurrence of ice ages: Benzi, Parisi, Sutera, Vulpiani

20 Dynamical gate operation in a YBS

21 Bistable selfswitching: depends on the bias voltage YBS as amplifier and rectier logic operation

22 SR: Working principle self-gating g leads to a bistable transfer characteristic the input and the working point voltages were set to bistable bl switching controlled by noise all 20K Input signal: V g ( t) V g 0 V sin( ), g t Weak periodic signal: V g mV

23 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.

24 Recording SR: Residence Time For the unmodulated system with f = 0 Hz the residence time distribution decays exponentially with the inverse of the Kramer s rate N L, H ( T ) From fitting: exp( T T T K T K ( )s ) (s) N L (T) T(s) Time matching condition of SR: T 2T K

25 Recording SR: Residence Time For f < f SR the residence time distribution is strongly controlled by the noise For f > f SR odd multiples of the periodic forcing T ω occur: T n ( 2n 1) T / f = 0.1 Hz f = 0.6 Hz T (s) 0.4 f = 1.8 Hz T (s) 0.4 f = 2.4 Hz T (s) T (s)

26 Recording SR: Residence Time At the optimum frequency f = 1 Hz the residence time distribution is almost perfectly restricted to the first peak. 0.4 (s) N L (T) T(s) The time scale condition of SR is fulfilled by tuning solely the frequency of the periodic forcing.

27 SR: Residence Time Distribution

28 Application: Magnetic field sensor Set the detector in the strongly noise activated regime Magnetic field applied perpendicular to the motion of electrons either in or out of the plane T H, L 1 n H, L n L H, i1 T H i, L i

29 r (V) Vb B Application: Magnetic field sensor V br,th V br decreases down Vbarrier (V) to a magnetic field threshold B th Transitions between B th -0,520-0,514-0,508-0,502-0,496-0, B (T) The magnetic-field induced switching is associated with a scattering asymmetry at the boundaries the two states occur between B Vbr r,th (V) Vbarrier (V) Bth B (T)

30 Application: Magnetic field sensor mean reside ence ti ime (s s) TH TL B (mt)

31 Application: Magnetic field sensor T (s) 1.5 Measurement 1.0 Simulation Linear Fit Output is a linear function of B around T = 0 s Target signal independent -0.5 sensitivity B( (mt) T ( B) T0 S ( B) T BB cb c

32 Outline Nanoelectronic semiconductor electronic devices Technology Nonlinear nanoelectronic transport 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 RTDs

33 Y-branch as ballistic rectification Rectification due to junctions: pn-junction Metal-semiconductor junction Y-branch junction: no geometrical asymmetry! V (Y) r 0,00 V l (X) V s (X AND Y) V r V s (V) -0, ,10 V s -0,15 Experiment Theory: diffusive ballistic -0,4-0,2 0,0 0,2 0,4 V l V xy (V)

34 Y-branch as ballistic rectification diffusive Transport V l V r 0,00-0,05 V s (V) -0,10 Quasi-ballistic Transport -0,15 diffusive ballistic V s -0,4 0,0 0,4 V xy (V)

35 YBS nonlinearity used for a compact adder Half-Adder: binary addition with carry bit Truth table X Y Z C H H L H Sh Scheme X & = AND Y & C = = XOR H L H L L H H L = Z L L L L > 10 FETs + interconnects t

36 Nanoelectronic Half-Adder planar Half-Adder is based on ballistic Y-junctions Inputs: x and y x g Outputs: c and z Working point: s Control: v v y c l z r 100 nm s L. Worschech et al., Appl. Phys. Lett. 83, 2462 (2003)

37 Model control of V z via V c : gate a) Injection of electrons l r s b) Gating No external gate! V c c R z V s V z Self induced switching V d

38 gate l r s 0.1 c z R=10M V s V z (V) 0.0 V s = 0.1 V 01V -0.2 V -0.3 V V -0.1 V c V V d V z -0.1 V d = 0.1 V V c (V) Self switching N-shaped V z (V c )-characteristics Definition of the working gpoint via V s

39 V out (V V) (H L) (H H) (L H) V Z Z V x l V C y c z V y x y c z gate V s R V c V d d r s V z V z (V V) V s = -0.3 V V x -V y (V) Push-Pull-Mode: V x + V y = 0.3 V Rectification: V c < (V x + V y )/2 Self induced Switching: M-shaped V z -characteristic V c (V)

40 V g Demonstration o of logic ogc function at RT: V x x V y y c z y c z V c l R V d r V z s V s z (V) V z 0,10 0,00 T = 4.2 K T = 50 K T = 300 K -0,10 X Y Z C H H L H H L H L L H H L V c (V) 000 0,00-0,25-0,50-0,75 (HH) (LH) (HL) (LL) (HH) (LH) (HL) (LL) L L L L Logic inputs (XY) (HH) (LH) (HL) (LL)

41 Dynamic properties of rectification 0,0 room temperature V S (V V) -0,5 1 AND Address Level 1 1-1,0 V S (V) ,0-0,5 0,0 0,5 1,0 V (V)

42 Microwave rectification: energy harvesting assuming V c V s 2 3T ballistic cavity A. N. Jordan, Markus Büttiker, PRB 2009 c with V f V sin( 1 t) ~ 2 1 e c 2 c 2 2 f1 ~ V s V~ V~ cos( t ) F

43 High Frequency Setup S-Parameter S 21 microwave cowvepower detected ec ed at 2 microwave power injected into 1

44 -V /2 o IS V S = 0 V o V Frequency doubling Injection Detection -70 P 2 (db Bm) -70 f = 100 MHz P f1 f 2 = 2f 1 P 2 (dbm) -80-1,0-0,5 0,0 V (V) f -90 2nd harmonic f 2 (GHz)

45 Microwave generates a DC current 10-2 T = 300 K I S (A 0,4 = 10 GHz )f1 10 dbm 0,2 8 dbm 6 dbm no microwave I S (A) f=10ghz 10-4 V C = -1 V 0,0-0,1 0,0 0,1 V(V) V C = 0.3 V P(dBm)

46 Outline Nanoelectronic semiconductor electronic devices Technology Nonlinear nanoelectronic transport 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 RTDs

47 Resonant-tunneling diode fast operation ~THz negative differential resistance ballistic operation at room temperature

48 RTD operation

49 Logic operation with RTD mesas V (mv) split RTD diameter: 600nm 0,00 0,25 0,50 0,75 1,00 1,25 1,50 V dc (V)

50 No thermal transconductance limit ultra small switching voltages

51 Logic RTD gates V ac = 23 mv V ac = 24.5 mv V ac = 25 mv V 1 = V 2 = 0 mv == Log. input I = I 1 +I 2 =0+0=0

52 Logic RTD gates V ac = 25 mv V ac = 26 mv V ac = 26.5 mv V 1 = 0,2 V 2 = 2,0 mv == Log. input I = I 1 +I 2 =1+0=0+1=1

53 Logic RTD gates V ac = 26.5 mv V ac = 27.5 mv V ac = 29 mv V 1 = V 2 = 2 mv == Log. input I = I 1 +I 2 =1+1=2

54 Logic RTD gates NOR NAND transition from NOR to NAND opertation for amplitude changes smaller than 1 mv

55 Logic stochastic resonance Murali, K., Sinha, S., Ditto, W., Bulsara, A. Phys. Rev. Lett. 102, (2009). Murali, K., Rajamohamed, I., Sinha, S., Ditto, W., and Bulsara, A., Appl. Phys. Lett. 95, (2009). L. W., F. Hartmann,T. Y. Kim,S. Höfling,M. Kamp,A. Forchel,J. Ahopelto,2I. Neri,A. Dari, L. Gammaitoni, APL 2010

56 RTD as light sensor and light-programmable LSR Counts P=0nW P=0.1 nw Gaussian Fit <VS> (mv)

57 Summary Introduction into different nanoelectronic devices Nonlinear transport: rectification, bistable switching Noise-induced switching, logic stochastic resonance Routes for energy harvesting in nanoelectronics

58 For important contributions many thanks to Transport: FH F. Hartmann, SK S. Kremling, S. SGöpfert, tad A. Dari, il. Gammaitoni Technology: M. Emmerling, S. Kuhn, T. Steinl, G. Heller, M. Kamp III-V samples: C. Schneider, S. Höfling, A. Forchel

59 Acknowledgement Support via EU: SUBTLE & NANOPOWER Many thanks for your attention!