1. Physical Phenomena for TeraHertz Electronic Devices
Jérémi TORRES
Institute of Electronics of the South
University Montpellier
France

2. Outline TeraHertz : Generalities Physical phenomena Plasma-waves
Optical-phonon resonance
Conclusions

3. 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

4. The TeraHertz “gap” Electronics Photonics Low cost Compact
f = 1012 Hz, 300 GHz - 10 THz, λ = 1 mm - 30 μm
Electronics
Photonics
Low cost
Compact
Room temperature
Continuous-wave
Tunable
Integration

5. Power vs frequency Proc. of IEEE 23, 10 (2005)
2005 survey of THz source performance, courtesy of Dr. J. Hesler,Virginia Diode Inc., Charlottesville, VA.
Terahertz Frequency Sensing and Imaging:A Time of Reckoning Future Applications?DWIGHT L. WOOLARD, FELLOW, IEEE, ELLIOTT R. BROWN, FELLOW, IEEE,MICHAEL PEPPER, AND MICHAEL KEMP, MEMBER, IEEE
PROCEEDINGS OF THE IEEE, VOL. 93, NO. 10, OCTOBER 2005
For example, a very recent surveyof the output power performance of the leading electronicsource technology is given in Fig. 2, which clearly shows thepersisting limitations within the THz gap, and it should benoted that the power efficiencies (i.e., which are not shown)are also very low, which is a problem for many practicalapplications. Furthermore, while it is true that there has beennoteworthy progress in very recent years (see discussionbelow), there was almost no commercially available THztechnology to speak of during the last century and what wasavailable could only be obtained at extremely high costs.
Proc. of IEEE 23, 10 (2005)

6. complexity, cost, magnetic field, maintenance, temperature
Optical THz Devices
Indirect
Laser Beating + photoconductor
Femtosecond laser + nonlinear cristal
Direct
Gas laser
Free electron laser
p-Ge laser
Quantum cascade laser
Difficulties:
complexity, cost, magnetic field, maintenance, temperature

7. 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

8. Main Features of THz Radiation
Non ionizing
Strong interaction with molecules
Transmitted through many materials
Higher resolution than microwaves

9. Applications in Spectroscopy
Physics: THz Time Domain Spectroscopy, dynamics of electrons, holes, phonons

10. Applications in Spectroscopy
Chemistry: chemical reactions, combustion, pollution, environment control
(Grischkowski, Oklahoma State Univ.)

11. Applications in Spectroscopy
Astronomy: atmospheric window, detection of molecules, atoms, ionized gas

12. Applications in Telecommunications
TeraHertz antennas, wireless communication
Terahertz fields and applicationsD. Dragoman, M. DragomanProgress in Quantum Electronics 28 (2004) 1–66
THz antennas. (a)–(d) broadside antennas: (a) dipole, (b) single-folded slot, (c) double-folded slot,(d) bowtie; (e)–(h) endfire antennas: (e) Vivaldi, (f) slot V antenna, (g, h) tapered slot.
Depending on the antenna thickness it ispossible that a large part of the radiated power (more than 90% in some situations)is trapped into the substrate. Therefore, small losses can only be obtained when THzantennas and propagating structures working at THz are patterned on very thinsubstrates.
Progr. Quant. Electr. 28, 1 (2004)

13. Applications in Art http://www.spiegel.de
FIG. 1. Top view ~not to scale! of the applied THz device structure ~a! cross
section of the TFMS line using gold for the signal lines and benzocyclobutene
~BCB! as a low-k dielectric material ~b!, and enlarged top view of
the band-pass filter ~c!, w516mm and l585mm.
Integrated THz technology for label-free genetic diagnostics
M. Nagel,a) P. Haring Bolivar, M. Brucherseifer, and H. Kurz
Institut fu¨r Halbleitertechnik, RWTH Aachen, Sommerfeldstr. 24, D Aachen, Germany
A. Bosserhoff and R. Bu¨ ttner
Institut fu¨r Pathologie, RWTH Aachen, Pauwelstr. 30, D Aachen, Germany
~Received 24 May 2001; accepted for publication 30 October 2001!
We report on a promising approach for the label-free analysis of DNA molecules using direct
probing of the binding state of DNA with electromagnetic waves at THz frequencies. Passive THz
resonator devices based on planar waveguides are used as sample carriers and transducers for THz
transmission analysis. In comparison to a formerly used free-space detection scheme, this method
provides a drastically enhanced sensitivity enabling analysis down to femtomol levels. We examine
the potential of our approach on biologically relevant DNA samples and demonstrate the detection
of single base mutations on DNA molecules.
APL VOLUME 80, NUMBER 1 7 JANUARY 2002
IG. 2. Magnitude of the transmission parameter S21 of the band-pass filtersloaded with denatured or hybridized DNA films on top ~5.4 kb vectorpcDNA3!. In comparison, the measured and simulated reference data of theunloaded filter.

14. Applications in Imaging (T-Ray)
Inspection materials/devices/systems
Industry
(Planken, Univ. Delft)

15. Applications in Imaging (T-Ray)
Medicine
Fig. 7. THz reflection image of a circular burned region on a tissue sample(chicken breast). The false color scale corresponds to the reflected THzamplitude in the frequency range 0:5–1:0 THz. Darker shades indicate lessreflected radiation
Tooth decay
(TeraView)

16. Applications in Imaging (T-Ray)
Medicine
Dermatology
(Teraview)

17. Applications in Imaging (T-Ray)
Security
eraView has worked closely with government and academic laboratories in the US and Europe to supply our Terahertz spectrometer (spectra series) and imaging (imaga series) products for detecting and identifying explosives and improvised explosive devices (IED) at stand-off distances of up to 1 m. Teraview has an expanding customer base in the instrumentation market and has focused considerable resource on supporting existing customers in these applications.
TeraView has worked with UK and US government agencies and commercial partners to demonstrate the capabilities of terahertz for non metallic weapons and explosives detection on people.The ability of the technology to spectrally identify explosives through clothing has led to the first successful proof of principle experiments at stand off distances for potential applications in building security, airports and defense. The imaging ability of the technology has led to proof of principle demonstrations of shoe scanning, as well as the world’s first practical terahertz system, based on a hand held wand that operates much like a metal detector, but capable of detecting non metallic weapons and certain explosives. The Company supports defense and government agencies, as well as commercial partners, who wish to further explore this technology.
Courtesy of Teraview

18. … exploiting plasma waves
1. THz Nanotransistors
… exploiting plasma waves

19. Experiments on InGaAs HEMTs
Origin of the peaks?
Appl. Phys. Lett. 80, 3433 (2002)

20. THz oscillations from plasma-waves
3D plasma oscillations
Analogy : harmonic oscillator
Tunable frequency with Vg
Practical applications :
High Electron Mobility Transistor

21. Travelling plasma waves
vdrift-vplasma
vdrift+vplasma

22. Travelling plasma waves
Mascaret over the Dordogne river

23. Stationary plasma waves
n = 1 f = 0.9 THz
n = 3 f = 2.7 THz
n\lambda=4L\Longleftrightarrow f=n\frac{\nu_{plasma}}{4L}

24. Plasma waves in HEMTs

25. Plasma synchronization by optical beating
THz
beating
Appl. Phys. Lett. 89, (2006)

26. Detection of THz beating + THz generation
Experiments
(detection)
Simulation
(generation+detection)
Frequency (GHz)
δ VDS
⟨VDS⟩
Appl. Phys. Lett. 89, (2006)

27. Resonant frequency vs swing voltage
Provides frequency tuning
IEEE J. Sel. Top. Quant. Electron. 14, 491 (2008)

28. Enhancing detection Simulation Experiments Modeling
Journ. Appl. Phys. 106, (2009)

29. Non resonant detection
THz imaging with HEMT
Non resonant detection
F. Teppe et al., to be published (2009)

30. Summary of plasma waves nanotransistors
Detector/Emitter
Room temperature
Frequency tuning
Integration
Emission mechanism?
Power?

31. … or exploiting the optical-phonon transit-time resonance in nitrides
2. TeraHertz MASER
… or exploiting the optical-phonon transit-time resonance in nitrides

32. Scattering rates in GaN at T=10 K
\tau^-\ll\tau^E\ll\tau^+
low energies: acoustic and impurity scattering
high energies: optical phonon emission
J. Appl. Phys. 89, 1161 (2001)

33. The optical-phonon transit-time resonance
Energy
acceleration τE
optical
phonon
Scattering rate
τ -
τ +
τ- : Average relaxation time
τE : Carrier transit time
τ+ : Time for optical phonon emission

34. Advantages of nitrides
Stronger electron-phonon coupling
Much sharper threshold
J. Appl. Phys. 89, 1161 (2001)

35. InN,
T=10 K

36. InN,
T=10 K

37. InN,
T=10 K

38. InN,
T=10 K

39. Summary of amplification bands
Phys. Rev. B 76, (2007)

40. Design of a cavity and emitted power
low E
large E
Gain depends on the electric field

41. Summary of TeraHertz MASER
Simple
Frequency tuning
High amplification
No magnetic field
77 K
High quality material
High field

42. Conclusions Exciting field for theory and experiments
Junction electronics/optics
New phenomena, materials, devices, systems

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