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Physical Phenomena for TeraHertz Electronic Devices. Jérémi TORRES Institute of Electronics of the South University Montpellier France. Outline. TeraHertz : Generalities Physical phenomena Plasma-waves Optical-phonon resonance Conclusions. The High-Frequency Investigation Group.

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Physical Phenomena for TeraHertz Electronic Devices

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Physical Phenomenafor TeraHertzElectronic Devices

  • Jérémi TORRES

  • Institute of Electronics of the South

  • University Montpellier

  • France


Outline

  • TeraHertz : Generalities

  • Physical phenomena

    • Plasma-waves

    • Optical-phonon resonance

    • Conclusions


The High-Frequency Investigation Group

Microwaves

Antennas/Radars

EM Compatibility

RFID

Theory

Monte Carlo

Hydrodynamic

Drift-Diffusion

Experiments

Photoexcitation

THz devices

Near-field

EM cartography


The TeraHertz “gap”

f = 1012 Hz, 300 GHz - 10 THz, λ = 1 mm - 30 μm

Electronics

Photonics

Low cost

Compact

Room temperature

Continuous-wave

Tunable

Integration


Power vs frequency

Proc. of IEEE 23, 10 (2005)


Optical THz Devices

  • Direct

    • Gas laser

    • Free electron laser

    • p-Ge laser

    • Quantum cascade laser

Indirect

  • Laser Beating + photoconductor

  • Femtosecond laser + nonlinear cristal

Difficulties:

complexity, cost, magnetic field, maintenance, temperature


Electronic THz Devices

  • Direct

    • Gunn, RTD, Impatt diodes

    • Schottky, varactor diodes

    • Magnetron, Carcinotron

    • FETs, HEMTs

Indirect

  • Multiplication

  • Nonlinearities

Difficulties:

current, temperature, contact resistance, efficiency, noise


Main Features of THz Radiation

  • Non ionizing

  • Strong interaction with molecules

  • Transmitted through many materials

  • Higher resolution than microwaves


Applications in Spectroscopy

Physics: THz Time Domain Spectroscopy, dynamics of electrons, holes, phonons


Applications in Spectroscopy

Chemistry: chemical reactions, combustion, pollution, environment control

(Grischkowski, Oklahoma State Univ.)


Applications in Spectroscopy

Astronomy: atmospheric window, detection of molecules, atoms, ionized gas


Applications in Telecommunications

TeraHertz antennas, wireless communication

Progr. Quant. Electr. 28, 1 (2004)


Applications in Art

http://www.spiegel.de


Applications in Imaging (T-Ray)

Inspection materials/devices/systems

Industry

(Planken, Univ. Delft)


Applications in Imaging (T-Ray)

Medicine

Tooth decay

(TeraView)


Applications in Imaging (T-Ray)

Medicine

Dermatology

(Teraview)


Applications in Imaging (T-Ray)

Security

Courtesy of Teraview


1. THz Nanotransistors

  • … exploiting plasma waves


Experiments on InGaAs HEMTs

Origin of the peaks?

Appl. Phys. Lett. 80, 3433 (2002)


THz oscillations from plasma-waves

3D plasma oscillations

Analogy : harmonic oscillator

Tunable frequency with Vg

Practical applications :

High Electron Mobility Transistor


vdrift-vplasma

Travelling plasma waves

vdrift+vplasma


Travelling plasma waves

Mascaret over the Dordogne river

http://www.archaero.com/mascaret.htm


Stationary plasma waves

n = 1 f = 0.9 THz

n = 3 f = 2.7 THz


Plasma waves in HEMTs


Plasma synchronization by optical beating

THz

beating

Appl. Phys. Lett. 89, 201101 (2006)


Frequency (GHz)

Detection of THz beating + THz generation

Experiments

(detection)

Simulation

(generation+detection)

δ VDS

⟨VDS⟩

Appl. Phys. Lett. 89, 201101 (2006)


5f0

3f0

f0

Resonant frequency vs swing voltage

Provides frequency tuning

IEEE J. Sel. Top. Quant. Electron. 14, 491 (2008)


Enhancing detection

Simulation

Experiments

Modeling

Journ. Appl. Phys. 106, 013717 (2009)


THz imaging with HEMT

Non resonant detection

F. Teppe et al., to be published (2009)


Summary of plasma waves nanotransistors


2. TeraHertz MASER

  • … or exploiting the optical-phonon transit-time resonance in nitrides


Scattering rates in GaN at T=10 K

low energies: acoustic and impurity scattering

high energies: optical phonon emission

J. Appl. Phys. 89, 1161 (2001)


The optical-phonon transit-time resonance

τ -

τ +

Scattering rate

optical

phonon

acceleration τE

Energy

τ- : Average relaxation time

τE : Carrier transit time

τ+ : Time for optical phonon emission


Advantages of nitrides

Stronger electron-phonon coupling

Much sharper threshold

J. Appl. Phys. 89, 1161 (2001)


InN,

T=10 K


InN,

T=10 K


InN,

T=10 K


InN,

T=10 K


Summary of amplification bands

Phys. Rev. B 76, 045333 (2007)


Design of a cavity and emitted power

low E

large E

Gain depends on the electric field


Summary of TeraHertz MASER


Conclusions

  • Exciting field for theory and experiments

  • Junction electronics/optics

  • New phenomena, materials, devices, systems


Sujet de stage

« Etude expérimentale des oscillations Gunn et de plasma téraHertz dans des composants de la micro-électronique »


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