Izaro LaresgoitiLow dimensional systems

Quantum tunnelingResonant tunneling RTD

StructureHow does it work?Materials

ApplicationsConclusions

α decay:Polonium -212 (alpha particle 8,78MeV)

LkC eT 22−∝

0.287eV

0.0807eV

0.287eV0.0807eV

χ21sin4)1( 22

LRRL

RL

RRRR

TTT+−

=

RLka ρρχ ++= 2

nπχ 2=

22 )(4

)1( RL

RL

LR

RLPK TT

TTRR

TTTT+

≈−

==

The condition for resonant states!

Assuming that TL and TR are small:

Near the resonance (TL and TR<<1)12

211)(

−

⎥⎥⎥⎥

⎦

⎤

⎢⎢⎢⎢

⎣

⎡

⎟⎟⎟⎟

⎠

⎞

⎜⎜⎜⎜

⎝

⎛

Γ

−+= pk

pk

EETET Breit-Wigner

1 2 3 4ã

0.2

0.4

0.6

0.8

1

T€€€€€€€€€€Tpk

Γ

Er

Scape rate

TL=TR=0.8

TL=TR=0.2

Regions (12-25nm)I-V: Emitter/collector(heavily doped(~108cm-3)

small bandgap, GaAs)II-IV: Q barrier(~0.23eV):larger bangap

(AlGaAs).III : QW: smaller bandgap

I

IIIIIIV

V

Important performance parameter:1.Peak current density (Jp)2.Valley current density (Jv)3.Peak to valley ratio (PVR): Jp/Jv

NDR

jp

jv

1. E1: Resonant energy2. E2: phonon

absorption3. E3: phonon emission 4. E4:Thermoionic

emission5. Non resonant

tunneling

Valley current

To obtain the better performance1. Maximize Ip

high frequency (>104

A/cm 2)

2. Minimize Ivreduce lekege current and hence the power consumtion.

3. Maximize PVR allow an

appropriate memory with a reasonable noise margin

4. Minimize RCt

NDR

Real current curve

To increase Ip: (increases f)1. Decrease the

thickness of the barrier

2. Increase the doping in the emitters

However:Increases also the IVDecreases the PVR

Trade off between high speed and power consumption!!

Small device (12-25nm/conventional device

~100nm)

Extremely high switching speed (e.g., 1 ps

switch, fmax~1 THz/215GHz conventional)

Low power consumption

Work at room temperature

Flexible design

NDR characteristics(Intrinsic bistability ,

incfrease functionality)

Type III-V (Eg. GaAs, InP)Good PVR and current density Ip~500kA/cm2

PVR ~52Good for high frequency switching applicationsCMOS incompatible and high cost

Si basedCMOS compatibleRTD Not good properties (NDR at low temp, PVR ~1.2-2.4)RITD

RITD type III-VRITD based in Si

Compatible with CMOSNDR at room TPVR~4Ip~2kA/cm2

Microwave oscillatorsNDR compensate the R

Ideal oscillator

Real oscillator

RTD avoid the amplitude decay

Novel digital logic circuits.(PVR=10 enough)Static memory (computer)

RTD more stable (NDR), bistability.Reduced the number of devices

The simplest configuration

Due to the continuous development of computer industry is inevitable the use of quantum based devices because they provide:

Low footprint and high device density.High switching speed(high computation capacity)Low power consumption

Due to their high switching velocity and the NDR RTDs are very useful for very high frequency oscillator circuits.

Books:

“The Physics and Applications of Resonant Tunnelling Diodes”. by Hiroshi Mizuta, Tomonori Tanoue. (Cambridge Studies in Semiconductor Physics and Microelectronic Engineering).

“Nanoelectronics and Information Technology: Advanced Electronic Materials and Novel Devices” by Rainer Waser

“The Physics of Low-dimensional Semiconductors: An Introduction” by John H. Davies

Papers and talks:

L.L. Chang, L. Esaki, and R. Tsu. “Resonant tunneling in semiconductor double barriers”, Appl. Phys. Lett. 24, 593 (1974).

S.L. Rommel, T.E. Dillon, M.W. Dashiell, H. Feng, J. Kolodzey, P.R. Berger, P.E. Thompson, K.D. Hobart, R. Lake, A.C. Seabaugh, G. Klimeck, and D.K. Blanks, “Room Temperature Operation of Epitaxially Grown Si/Si0.5Ge0.5/Si Resonant Interband Tunneling Diodes “, Appl. Phy. Lett, 73, 2191 (1998).

“Resonant Tunneling Diodes: Theory of Operation and Applications”. Johnny Ling, University of Rochester, Rochester , NY 14627

“Brief overview of nanoelectronic devices”, James C. Ellenbogen. Government Microelectronics Applications Conference (GOMAC98).

“Resonant Tunneling Transistor Characteristics Using a Fabry-Pariot Resonator”. Chomsik Lee. Journ. Korean Physic. Soc, vol 31

“Long journey into tunneling”. Leo Esaki. Nobel Lecture, December 12, 1973

“Confined Electrons and Photons. New Physics and Application”. Elias Burstein and Claude weisbuch

“Extending CMOS: Quantum functional Circuits Using Si-Based Resonant Interband Tunneling Diodes”. Paul R. Berger. March 11, 2005

“Resonant Tunneling Diodes”. Ni, Man. Advanced Electronic Devices. April 26. 2005

“ Quantum Wells, Wires, Dots; Quantum Coherent Devices”, Stephen Goodnick. IEEE Nanotechnology Conference in 2003

nanoHUB: online simulations and more: https://www.nanohub.org/tools/rtd/ (Simulate 1D resonant tunneling devices and other heterostructures via ballistic quantum transport)