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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 l.jpg

Physical Phenomenafor TeraHertzElectronic Devices

  • Jérémi TORRES

  • Institute of Electronics of the South

  • University Montpellier

  • France


Outline l.jpg

Outline

  • TeraHertz : Generalities

  • Physical phenomena

    • Plasma-waves

    • Optical-phonon resonance

    • Conclusions


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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


Slide4 l.jpg

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 l.jpg

Power vs frequency

Proc. of IEEE 23, 10 (2005)


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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


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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


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Main Features of THz Radiation

  • Non ionizing

  • Strong interaction with molecules

  • Transmitted through many materials

  • Higher resolution than microwaves


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Applications in Spectroscopy

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


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Applications in Spectroscopy

Chemistry: chemical reactions, combustion, pollution, environment control

(Grischkowski, Oklahoma State Univ.)


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Applications in Spectroscopy

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


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Applications in Telecommunications

TeraHertz antennas, wireless communication

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


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Applications in Art

http://www.spiegel.de


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Applications in Imaging (T-Ray)

Inspection materials/devices/systems

Industry

(Planken, Univ. Delft)


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Applications in Imaging (T-Ray)

Medicine

Tooth decay

(TeraView)


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Applications in Imaging (T-Ray)

Medicine

Dermatology

(Teraview)


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Applications in Imaging (T-Ray)

Security

Courtesy of Teraview


1 thz nanotransistors l.jpg

1. THz Nanotransistors

  • … exploiting plasma waves


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Experiments on InGaAs HEMTs

Origin of the peaks?

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


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THz oscillations from plasma-waves

3D plasma oscillations

Analogy : harmonic oscillator

Tunable frequency with Vg

Practical applications :

High Electron Mobility Transistor


Travelling plasma waves l.jpg

vdrift-vplasma

Travelling plasma waves

vdrift+vplasma


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Travelling plasma waves

Mascaret over the Dordogne river

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


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Stationary plasma waves

n = 1 f = 0.9 THz

n = 3 f = 2.7 THz


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Plasma waves in HEMTs


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Plasma synchronization by optical beating

THz

beating

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


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Frequency (GHz)

Detection of THz beating + THz generation

Experiments

(detection)

Simulation

(generation+detection)

δ VDS

⟨VDS⟩

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


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5f0

3f0

f0

Resonant frequency vs swing voltage

Provides frequency tuning

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


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Enhancing detection

Simulation

Experiments

Modeling

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


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THz imaging with HEMT

Non resonant detection

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


Summary of plasma waves nanotransistors l.jpg

Summary of plasma waves nanotransistors


2 terahertz maser l.jpg

2. TeraHertz MASER

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


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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)


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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 l.jpg

Advantages of nitrides

Stronger electron-phonon coupling

Much sharper threshold

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


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InN,

T=10 K


Slide36 l.jpg

InN,

T=10 K


Slide37 l.jpg

InN,

T=10 K


Slide38 l.jpg

InN,

T=10 K


Summary of amplification bands l.jpg

Summary of amplification bands

Phys. Rev. B 76, 045333 (2007)


Design of a cavity and emitted power l.jpg

Design of a cavity and emitted power

low E

large E

Gain depends on the electric field


Summary of terahertz maser l.jpg

Summary of TeraHertz MASER


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Conclusions

  • Exciting field for theory and experiments

  • Junction electronics/optics

  • New phenomena, materials, devices, systems


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Sujet de stage

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


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