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27 results on '"Y. Roelens"'

1. High Breakdown Voltage GaN Schottky Diodes for THz Frequency Multipliers

Author

G. Di Gioia, E. Frayssinet, M. Samnouni, V. Chinni, P. Mondal, J. Treuttel, X. Wallart, M. Zegaoui, G. Ducournau, Y. Roelens, Y. Cordier, M. Zaknoune, Advanced NanOmeter DEvices - IEMN (ANODE - IEMN), Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Centrale Lille-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-JUNIA (JUNIA), Université catholique de Lille (UCL)-Université catholique de Lille (UCL)-Centrale Lille-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-JUNIA (JUNIA), Université catholique de Lille (UCL)-Université catholique de Lille (UCL), Centre de recherche sur l'hétéroepitaxie et ses applications (CRHEA), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA), EPItaxie et PHYsique des hétérostructures - IEMN (EPIPHY - IEMN), LERMA Cergy (LERMA), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), Photonique THz - IEMN (PHOTONIQUE THZ - IEMN), This work was supported by the French ANR (Agence Nationale de la Recherche), under the CE24 ‘SchoGAN’ project. This work was also supported by the CPER 'Photonics for Society', the CPER 'WAVETECH', and the Hauts de France Regional Council and the French Network RENATECH, Renatech Network, and ANR-17-CE24-0034,SchoGaN,Diodes Schottky GaN pour la génération de signaux THz(2017)

Subjects
wide band gap semiconductor, Materials Chemistry, Schottky diode, frequency multipliers, THz, Electrical and Electronic Engineering, Condensed Matter Physics, Electronic, Optical and Magnetic Materials, GaN, [SPI.TRON]Engineering Sciences [physics]/Electronics
Abstract

International audience; Quasi-vertical gallium nitride (GaN) Schottky diodes on silicon carbide (SiC) substrates were fabricated for frequency multiplier applications. The epitaxial structure employed had an n− layer of 590 nm with doping 6.6 × 1016 cm−3, while the n+ layer was 950 nm thick, with doping 2 × 1019 cm−3. Potassium hydroxide (KOH) chemical surface treatment before Schottky contact metallization was employed to study its effect in improving the diode parameters. The KOH-treated diode demonstrated a breakdown voltage of − 27.5 V, which is the highest reported for this type of diode. Cut-off frequencies around 500 GHz were obtained at high reverse bias (− 25 V) in spite of high series resistance. The result obtained in breakdown voltage value warrants further research in surface treatment and post-annealing of the Schottky contact optimization in order to decrease the series resistance.

Published
2023
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2. Comprehensive model for ideal reverse leakage current components in Schottky barrier diodes tested in GaN-on-SiC samples

Author

B. Orfao, G. Di Gioia, B. G. Vasallo, S. Pérez, J. Mateos, Y. Roelens, E. Frayssinet, Y. Cordier, M. Zaknoune, T. González, Universidad de Salamanca, Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Centrale Lille-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-JUNIA (JUNIA), Université catholique de Lille (UCL)-Université catholique de Lille (UCL), Advanced NanOmeter DEvices - IEMN (ANODE - IEMN), Université catholique de Lille (UCL)-Université catholique de Lille (UCL)-Centrale Lille-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-JUNIA (JUNIA), Departamento de Fisica Aplicada [Salamanca], Centre de recherche sur l'hétéroepitaxie et ses applications (CRHEA), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA), This work has been partially supported through Grant No. PID2020-115842RB-I00 funded by No. MCIN/AEI/10.13039/501100011033. B. Orfao acknowledges the Ph.D. contract from the Junta de Castilla y León. This work was also supported by the French ANR (Agence National de la Recherche) through the project SchoGaN (No. ANR-17-CE24-0034), the 'Investissements d’Avenir' program GaNeX (No. ANR-11-LABX-0014), and the French network Renatech., Renatech Network, CMNF, ANR-11-LABX-0014,GANEX,Réseau national sur GaN(2011), and ANR-17-CE24-0034,SchoGaN,Diodes Schottky GaN pour la génération de signaux THz(2017)

Subjects
Schottky barrier diode, [SPI]Engineering Sciences [physics], Semiconductor structures, Electrical properties and parameters, General Physics and Astronomy, Current-voltage characteristic, Thermionic emission
Abstract

International audience; A model to predict the ideal reverse leakage currents in Schottky barrier diodes, namely, thermionic emission and tunneling components, has been developed and tested by means of current–voltage–temperature measurements in GaN-on-SiC devices. The model addresses both current components and both forward and reverse polarities in a unified way and with the same set of parameters. The values of the main parameters (barrier height, series resistance, and ideality factor) are extracted from the fitting of the forward-bias I–V curves and then used to predict the reverse-bias behavior without any further adjustment. An excellent agreement with the I–V curves measured in the forward bias in the GaN diode under analysis has been achieved in a wide range of temperatures (275–475 K). In reverse bias, at temperatures higher than 425 K, a quasi-ideal behavior is found, but additional mechanisms (most likely trap-assisted tunneling) lead to an excess of leakage current at lower temperatures. We demonstrate the importance of the inclusion of image-charge effects in the model in order to correctly predict the values of the reverse leakage current. Relevant physical information, like the energy range at which most of the tunnel injection takes place or the distance from the interface at which tunneled electrons emerge, is also provided by the model.

Published
2022
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3. Ballistic nanodevices for terahertz data processing: Monte Carlo simulations

Author

Y. Roelens, Alain Cappy, Daniel Pardo, Beatriz G. Vasallo, Tomas Gonzalez, J.S. Galloo, Javier Mateos, and Sylvain Bollaert

Subjects
Materials science, Condensed matter physics, business.industry, Terahertz radiation, Mechanical Engineering, Monte Carlo method, Bioengineering, General Chemistry, Electron, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, Multiplexer, Space charge, Mechanics of Materials, Ballistic conduction, Optoelectronics, General Materials Science, Electric potential, Electrical and Electronic Engineering, business, Diode
Abstract

By using a semi-classical two-dimensional Monte Carlo simulation, simple devices (T-branch junctions (TBJs) and rectifying diodes) based on AlInAs/InGaAs ballistic channels are analysed. Initially, the model is validated by means of Hall-effect measurements of mobility and electron concentration in long (diffusive) channels. Then, quasi-ballistic transport at room temperature is confirmed in a 100 nm channel. Our simulations qualitatively reproduce the experimental results of electric potential measured in a TBJ appearing as a result of electron ballistic transport, and in close relation with the presence of space charge inside the structure. As examples of devices exploiting the ballistic transport of electrons, preliminary simulations of a multiplexor/demultiplexor and a rectifying diode are presented, demonstrating their capability for terahertz operation.

Published
2003
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4. Terahertz emission induced by optical beating in nanometer-length field-effect transistors

Author

Luca Varani, Y. Roelens, Stéphane Blin, Jérémi Torres, Pavel Shiktorov, Viktoras Gruzinskis, T. Laurent, Andrey Shchepetov, Sylvain Bollaert, Frederic Teppe, Christophe Palermo, Hugues Marinchio, E. Starikov, Philippe Nouvel, Institut d’Electronique et des Systèmes (IES), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM), Térahertz, hyperfréquence et optique (TéHO), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM), Institut d’Électronique, de Microélectronique et de Nanotechnologie (IEMN) - UMR 8520 (IEMN), Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Université Polytechnique Hauts-de-France (UPHF)-Ecole Centrale de Lille-Université Polytechnique Hauts-de-France (UPHF)-Institut supérieur de l'électronique et du numérique (ISEN), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Charles Coulomb (L2C), Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), and Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)

Subjects
010302 applied physics, [PHYS]Physics [physics], Materials science, business.industry, Terahertz radiation, Transistor, Induced high electron mobility transistor, General Physics and Astronomy, 02 engineering and technology, Plasma, 021001 nanoscience & nanotechnology, 01 natural sciences, law.invention, Computer Science::Hardware Architecture, Quality (physics), law, 0103 physical sciences, Optoelectronics, Field-effect transistor, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, 0210 nano-technology, business, Fermi gas, Spectral purity
Abstract

International audience; We report on photo-induced terahertz radiation with a high spectral purity generated by a submicron sized InGaAs-based high-electron-mobility transistor. The emission peak is due to the electron-hole pairs photocreated in the transistor channel at the frequency of the beating of two cw- laser sources. The radiation frequency corresponds to the lowest fundamental plasma mode in the gated region of the transistor channel. The observed high emission quality factor at 200K is interpreted as a result of stream-plasma instability in the two-dimensional electron gas whose appearance is emphasized by the reduction of the velocity relaxation rate with the temperature.

Published
2012
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5. Evidence of surface charge effects in T-branch nanojunctions using microsecond-pulse testing

Author

Ignacio Iniguez-de-la-Torre, Tomas Gonzalez, C. Gardès, Javier Mateos, Y. Roelens, Sylvain Bollaert, Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), and Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)

Subjects
Ballistic transport, Materials science, Bioengineering, Nanotechnology, 02 engineering and technology, 01 natural sciences, Ballistic conduction, 0103 physical sciences, General Materials Science, Surface charge, 22 Física, Electrical and Electronic Engineering, Nanodevices, Surface states, 010302 applied physics, business.industry, Mechanical Engineering, General Chemistry, 021001 nanoscience & nanotechnology, 3. Good health, Pulse (physics), Monte Carlo method, Microsecond, Mechanics of Materials, Optoelectronics, Pulsed measurements, 0210 nano-technology, business, Ultrashort pulse, Pulse-width modulation, Voltage
Abstract

The understanding of the influence of surface charge effects on the electrical properties of nanostructures is a key aspect for the forthcoming generations of electronic devices. In this work, by using an ultrafast electrical pulse characterization technique, we report on the room-temperature time response of a T-branch nanojunction which allows identifying the signature of surface states. Different pulse widths from 500 ns to 100 µs were applied to the device. For a given pulse width, the stem voltage is measured and compared with the DC result. The output value in the stem is found to depend on the pulse width and to be related to the characteristic charging time of the interface states. As expected, the results show that the well-know nonlinear response of T-branch junctions is more pronounced for long pulses, beyond such a characteristic time., ROOTHz (FP7-243845)

Published
2011
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6. 100mV noise performances of Te-doped Sb-HEMT

Author

Ludovic Desplanque, A. Olivier, A. Noudeviwa, N. Wichmann, Sylvain Bollaert, Xavier Wallart, Y. Roelens, N. Waldhoff, Francois Danneville, Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), and Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)

Subjects
Materials science, Noise measurement, business.industry, 020208 electrical & electronic engineering, Transistor, Doping, Electrical engineering, chemistry.chemical_element, 020206 networking & telecommunications, 02 engineering and technology, High-electron-mobility transistor, Temperature measurement, Noise (electronics), law.invention, chemistry, law, 0202 electrical engineering, electronic engineering, information engineering, Optoelectronics, Tellurium, business, DC bias
Abstract

In this paper, we present the noise measurement results of InAs/AlSb HEMTs at room temperature under very low drain bias (100mV) at 30GHz. Under these dc bias conditions the transistor exhibit NF min =1.56 dB and G ass =5.3dB @30 GHz for P dc = 7.3µW/µm. These results are compared to our previous work and the great improvements observed open up the possibility to develop a 100mV electronics at room temperature.

Published
2010
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7. Tellurium δ-doped 120nm AlSb/InAs HEMTs: towards sub-100mV electronics

Author

Xavier Wallart, N. Wichmann, Sylvain Bollaert, A. Olivier, Y. Roelens, Francois Danneville, Ludovic Desplanque, and A. Noudeviwa

Subjects
010302 applied physics, Materials science, Condensed matter physics, business.industry, Transconductance, Doping, Biasing, 02 engineering and technology, High-electron-mobility transistor, 021001 nanoscience & nanotechnology, Noise figure, 01 natural sciences, Noise (electronics), Cutoff frequency, 0103 physical sciences, Optoelectronics, 0210 nano-technology, business, Ohmic contact
Abstract

In this paper, we have investigated f T variations under ultra low drain bias conditions of state of the art 120nm gate length AlSb/InAs HEMT featuring a f T / f max of 303GHz /227GHz under high bias conditions and a f T of 143GHz at 100mV drain bias voltage. A nearly linear dependence of f T versus V ds up to 100mV was observed and explained. This dependence means that f T could be easily tailored with V ds for a given application. Some points should now be investigated like the dependence of noise parameters under these low bias conditions. Unpublished studies on previous devices let us expected to obtain equal or better minimum Noise Figure NF min (1.56dB) and associated Gain G ass (5.32dB) at 30 GHz for a 100mV drain bias.

Published
2010
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8. Fabrication and characterization of 200-nm self-aligned In0.53Ga0.47As MOSFET

Author

A. Olivier, M. P. Chauvat, Xavier Wallart, Gilles Dambrine, Pierre Ruterana, Yi Wang, N. Wichmann, Francois Danneville, Jiongjiong Mo, Y. Roelens, Sylvain Bollaert, A. Noudeviwa, O. Desplats, Jérôme Saint-Martin, Hassan Maher, F. Martin, Ming Shi, and Ludovic Desplanque

Subjects
010302 applied physics, Fabrication, Materials science, Silicon, business.industry, Transconductance, chemistry.chemical_element, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Atomic layer deposition, chemistry.chemical_compound, Ion implantation, Silicon nitride, chemistry, Gate oxide, 0103 physical sciences, MOSFET, Optoelectronics, 0210 nano-technology, business
Abstract

In this paper, a 200 nm n-channel inversion-type self-aligned In 0.53 Ga 0.47 As MOSFET with a Al 2 O 3 gate oxide deposited by Atomic Layer Deposition (ALD) is demonstrated. Two ion implantation processes using silicon nitride side-wall are performed for the fabrication of the n-type source and drain regions. The 200 nm gate-length MOSFET with a gate oxide thickness of 8 nm features the transconductance of 70 mS/mm and the maximum drain current of 200 mA/mm.

Published
2010
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9. Technological bricks and concepts for THz remote sensing

Author

Pierre Legagneux, Daniel Dolfi, A. De Rossi, J. P. Schnell, Jérémi Torres, P. Guiset, G. Pillet, Sylvain Bollaert, Laurent Chusseau, Hugues Marinchio, Y. Roelens, R. Czarny L. Morvan, Philippe Nouvel, Luca Varani, S. Megtert, J-F. Lampin, Thales Research and Technology [Palaiseau], THALES, Thales Research and Technologies [Orsay] (TRT), Unité mixte de physique CNRS/Thales (UMPhy CNRS/THALES), Centre National de la Recherche Scientifique (CNRS)-THALES, Institut d’Electronique et des Systèmes (IES), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Térahertz, hyperfréquence et optique (TéHO), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Radiations et composants (RADIAC), Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF), THALES [France], and THALES [France]-Centre National de la Recherche Scientifique (CNRS)

Subjects
Terahertz radiation, Computer science, Amplifier, Local oscillator, Vacuum tube, Detector, Physics::Optics, 02 engineering and technology, 021001 nanoscience & nanotechnology, proceedings, 7. Clean energy, 01 natural sciences, law.invention, Semiconductor laser theory, law, 0103 physical sciences, Hardware_INTEGRATEDCIRCUITS, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, 010306 general physics, 0210 nano-technology, Realization (systems), ComputingMilieux_MISCELLANEOUS, Remote sensing, Common emitter
Abstract

We present technological bricks and concepts under study which could permit build up of future THz remote sensing systems. Critical issues regarding such systems mainly rely on the availability of sensitive and compact detectors together with powerful and versatile sources. Potential use of plasma waves in nano-transistor is presented which can be exploited for the realization of an efficient mixer operating at THz frequencies to be implemented in a coherent detection scheme. In such a scheme the necessary local oscillator is obtained from a solid state dual frequency laser whose architecture is also detailed. On the emitter side, the preliminary realization of sub-millimeter wave to THz amplifier based an vacuum tube technology, including carbon nano-tubes is also presented.

Published
2010

10. Efficient terahertz mixer from plasma wave downconversion in InGaAs HEMT

Author

Laurent Chusseau, Luca Varani, Philippe Nouvel, J.F. Lampin, Y. Roelens, H. Marinchio, Sylvain Bollaert, Jérémi Torres, Daniel Dolfi, Institut d’Electronique et des Systèmes (IES), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Térahertz, hyperfréquence et optique (TéHO), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF), Thales Research and Technology [Palaiseau], THALES [France], and THALES

Subjects
010302 applied physics, Physics, Terahertz radiation, business.industry, Waves in plasmas, Biasing, 02 engineering and technology, Plasma, High-electron-mobility transistor, 021001 nanoscience & nanotechnology, Plasma oscillation, 01 natural sciences, [SPI.TRON]Engineering Sciences [physics]/Electronics, chemistry.chemical_compound, Optics, chemistry, 0103 physical sciences, Field-effect transistor, 0210 nano-technology, business, Indium gallium arsenide, ComputingMilieux_MISCELLANEOUS
Abstract

Two-dimensional (2D) plasma waves in field effect transistors are well known since the pioneer work of Dyakonov and Shur. The application to terahertz (THz) detection was proven recently both at cryogenic and room temperatures. Aside from these experiments, we used the interband photoexcitation brought by the difference-frequency component of a photomixed laser beam to excite very efficiently plasma waves in HEMT channel at room temperature. Owing to a specific experimental setup avoiding unwanted high-frequency electrical oscillations of the HEMTs, we obtained the spectral profiles of THz 2D plasma waves resonances of InGaAs HEMTs for many experimental conditions. The effect of geometrical HEMTs parameters (lengths of the gate and surrounding regions) as well as biasing conditions (drain and gate voltages) was evaluated on both plasma oscillations frequencies and amplitudes. Simultaneously, a numerical approach, based on hydrodynamic equations coupled to a pseudo-2D Poisson solver, was developed that compares well with experiments. Using this unique combination of experiments and numerical simulations, a comprehensive spectroscopy of plasma waves in HEMTs is thus obtained. It provides a deeper insight into the physical processes involved in plasma wave excitation and allows predicting for mixer operation at THz frequency only using the plasma wave nonlinearity. Mixing experiments are under progress.

Published
2010
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11. Oblique modes effect on terahertz plasma wave resonant detection in InGaAs/InAlAs multichannel transistors

Author

Andrey Shchepetov, Y. Roelens, S. Boubanga-Tombet, Dalius Seliuta, H. Videlier, S. Nadar, Dominique Coquillat, C. Gardès, Nina Dyakonova, Sylvain Bollaert, R. Vadoklis, Gintaras Valušis, A. Cappy, Wojciech Knap, Frederic Teppe, Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), and Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)

Subjects
010302 applied physics, Materials science, Physics and Astronomy (miscellaneous), business.industry, Waves in plasmas, Terahertz radiation, Transistor, Oblique case, 02 engineering and technology, Plasma, 021001 nanoscience & nanotechnology, 01 natural sciences, law.invention, Gallium arsenide, Laser linewidth, chemistry.chemical_compound, chemistry, law, 0103 physical sciences, Optoelectronics, Ingaas inalas, 0210 nano-technology, business
Abstract

We report on the demonstration of narrow terahertz plasma wave resonant detection at low temperature in 200nm gate length InGaAs∕InAlAs multichannel high electron mobility transistors. We observe that the resonant detection linewidth is smaller than in full channel high electron mobility transistors. We interpret this shrinking by the effect of multichannel geometry that does not allow oblique plasma mode propagation along the channel.

Published
2008
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12. Plasma oscillations in nanotransistors for room temperature detection and emission of terahertz radiation

Author

Didier Theron, A. El Fatimy, R. Tauk, Wojciech Knap, S. Boubanga, C. Gaquiere, Alain Cappy, Erwan Morvan, N. Dyakonova, Y. Roelens, Taiichi Otsuji, J. Lyonnet, M.A. Poisson, Sylvain Bollaert, Frederic Teppe, Andrey Shchepetov, Y. M. Meziani, Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), and Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)

Subjects
010302 applied physics, Physics, Waves in plasmas, Terahertz radiation, business.industry, Transistor, 02 engineering and technology, High-electron-mobility transistor, Electron, Plasma, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Plasma oscillation, 01 natural sciences, 7. Clean energy, law.invention, law, 0103 physical sciences, Optoelectronics, Emission spectrum, 0210 nano-technology, business
Abstract

In this work we present experimental results on room temperature terahertz (THz) detection/emission from nanotransistors as well as double grating gates structures. It shows that the emission spectra from GaN/AlGaN HEMT transistor can be successfully interpreted in the frame of the Dyakonov-Shur model which predicts that by heating/accelerating the electrons up to velocities comparable with plasma wave velocity can lead to instability and generation of plasma waves in the transistor channel. Studies of the current dependence of THz detection by InGaAs based HEMT is also presented. It is shown that in realistic transistor structures the room temperature resonant THz detection can be observed only upon applying a current high enough to produce fast/hot electrons. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Published
2008
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13. Current driven resonant plasma wave detection of terahertz radiation : toward the Dyakonov-Shur instability

Author

S. Nadar, Andrey Shchepetov, Y. Roelens, Dalius Seliuta, Gintaras Valušis, Wojciech Knap, S. Boubanga-Tombet, Sylvain Bollaert, C. Gardès, R. Vadoklis, Dominique Coquillat, H. Videlier, Frederic Teppe, Nina Dyakonova, Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), and Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)

Subjects
010302 applied physics, Physics, Physics and Astronomy (miscellaneous), Waves in plasmas, business.industry, Terahertz radiation, Transistor, Bolometer, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Instability, law.invention, Gallium arsenide, chemistry.chemical_compound, chemistry, law, 0103 physical sciences, Optoelectronics, Electromagnetic electron wave, Current (fluid), 0210 nano-technology, business
Abstract

The experiments on the dc current influence on resonant terahertz plasma wave detection in InGaAs∕InAlAs multichannel high electron mobility transistors are reported. We observed the line width shrinking when a dc current is applied. We show that this line width decrease is due to the current induced reduction of plasma wave damping and takes place because the current drives the system toward the Dyakonov-Shur plasma wave instability.

Published
2008
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14. Experimental and theoretical investigation of terahertz optical-beating detection by plasma waves in high electron mobility transistors

Author

Andrey Shchepetov, Christophe Palermo, Viktoras Gruzinskis, Luca Varani, Hugues Marinchio, G. Sabatini, Y. Roelens, Sylvain Bollaert, Pavel Shiktorov, Philippe Nouvel, Frederic Teppe, Laurent Chusseau, E. Starikov, Jérémi Torres, Institut d’Electronique et des Systèmes (IES), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM), Térahertz, hyperfréquence et optique (TéHO), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM), Radiations et composants (RADIAC), Institut d’Électronique, de Microélectronique et de Nanotechnologie (IEMN) - UMR 8520 (IEMN), Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Université Polytechnique Hauts-de-France (UPHF)-Ecole Centrale de Lille-Université Polytechnique Hauts-de-France (UPHF)-Institut supérieur de l'électronique et du numérique (ISEN), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Groupe d'étude des semiconducteurs (GES), Université Montpellier 2 - Sciences et Techniques (UM2)-Centre National de la Recherche Scientifique (CNRS), Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF), and Centre National de la Recherche Scientifique (CNRS)-Université Montpellier 2 - Sciences et Techniques (UM2)

Subjects
[PHYS]Physics [physics], business.industry, Terahertz radiation, Chemistry, Physics::Optics, 02 engineering and technology, Plasma, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Plasma oscillation, Laser, 01 natural sciences, [SPI.TRON]Engineering Sciences [physics]/Electronics, law.invention, Photoexcitation, Optics, law, Harmonics, 0103 physical sciences, Poisson's equation, 010306 general physics, 0210 nano-technology, business, Excitation
Abstract

International audience; A photomixed laser beam of two 1.55 μm lasers is used to obtain interband photoexcitation at the difference frequency and at room temperature in suvmicron gate length INAIA/InGaAs transistors. Results show the clear excitation of plasma oscillation modes in the transistors channel Fundamental plasma resonant frequency and its add harmonics can be tuned with the applied gate voltage. Numerical simulation have also been performed using a hydrodynamic approach coupled to a pseudo-2D Poisson equation. Numerical results are in qualitative agreement with experiments and confirm optical beatin detection at terahertz frequencies.

Published
2008
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15. Ballistic nano-devices for high frequency applications

Author

Alain Cappy, Sylvain Bollaert, Javier Mateos, Beatriz G. Vasallo, Xavier Wallart, Tomas Gonzalez, J.S. Galloo, C. Gardes, Z. Teukam, Y. Roelens, L. Berdnarz, Isabelle Huynen, Benoît Hackens, Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), and Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)

Subjects
010302 applied physics, Limiting factor, Materials science, Nano devices, business.industry, Terahertz radiation, Monte Carlo method, Metals and Alloys, 02 engineering and technology, Surfaces and Interfaces, 021001 nanoscience & nanotechnology, 01 natural sciences, Multiplexer, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, High impedance, 0103 physical sciences, Materials Chemistry, Optoelectronics, 0210 nano-technology, business
Abstract

In this paper, we present a study on three-terminal ballistic junction and their applications to rectifiers and MUX/DEMUX. Rectifying effect is observed up to 94 GHz at room temperature. Although THz frequency performance has been demonstrated by Monte Carlo simulation, the high impedance of the nano-device combined with the parasitic capacitances is a limiting factor. (c) 2006 Published by Elsevier B.V.

Published
2007
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16. Characterization of superconductor coplanar resonators deposited on different substrates by thermal coevaporation

Author

G. Alquié, D. Seron, J.C. Carru, N.E. Bourzgui, Hamid Kokabi, Y. Roelens, Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF), Laboratoire d'Etude des Matériaux et des Composants pour l'Electronique (LEMCEL), and Université du Littoral Côte d'Opale (ULCO)

Subjects
010302 applied physics, High-temperature superconductivity, Materials science, Barium oxide, Scanning electron microscope, Analytical chemistry, Condensed Matter Physics, Microstructure, 01 natural sciences, Electronic, Optical and Magnetic Materials, law.invention, Surface conductivity, chemistry.chemical_compound, [SPI]Engineering Sciences [physics], chemistry, law, 0103 physical sciences, Thin film, 010306 general physics, Microwave, Sheet resistance
Abstract

This study is based on two commercially available YBCO thin films deposited by the thermal coevaporation method on different substrates (MgO and LaAlO3). Those films should be optimized for microwave applications. The structure and microstructure of the film deposited on LaAlO3 have been investigated, respectively by XRD and SEM. These characterizations showed the high quality of the films concerning the c-axis orientation and the smooth and homogenous morphology. The films have then been etched into two different coplanar line resonators by ionic method (YBCO/LaAlO3) and chemical one (YBCO/MgO) and their microwave properties have been characterized in two different cryogenic experimental set-ups. Despite the differences between these coplanar resonators, we have obtained the same intrinsic parameters (λ0 = 190 nm, Tc=87 K with γ = 3) corresponding to the data provided by THEVA and a very low surface resistance (Rs=0.4 m Ω at 31 K and 10 GHz).

Published
2006
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17. InP based ballistic nanodevices

Author

Y. Roelens, Wojciech Knap, Sylvain Bollaert, Alain Cappy, Tomas Gonzalez, J.S. Galloo, Javier Mateos, Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), and Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)

Subjects
010302 applied physics, Electron mobility, Materials science, business.industry, Waves in plasmas, Transistor, Physics::Optics, Nanotechnology, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, 01 natural sciences, law.invention, Gallium arsenide, Condensed Matter::Materials Science, chemistry.chemical_compound, Nanoelectronics, chemistry, law, Ballistic conduction, 0103 physical sciences, Indium phosphide, Optoelectronics, Nanometre, 010306 general physics, business
Abstract

The paper presents the state of the art and the future trends in the field of AlInAs/GaInAs/InP based nanometre devices, in particular ballistic T junctions and plasma wave transistors.

Published
2005

18. Voltage tuneable terahertz emission from a ballistic nanometer InGaAs/InAlAs transistor

Author

Nina Dyakonova, Y. Roelens, Alain Cappy, Javier Mateos, Tomas Gonzalez, Sylvain Bollaert, J. Lusakowski, Wojciech Knap, Krzysztof Karpierz, Luca Varani, Groupe d'étude des semiconducteurs (GES), Centre National de la Recherche Scientifique (CNRS)-Université Montpellier 2 - Sciences et Techniques (UM2), Centre d'Electronique et de Micro-optoélectronique de Montpellier (CEM2), Université Montpellier 2 - Sciences et Techniques (UM2)-Centre National de la Recherche Scientifique (CNRS), Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), and Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)

Subjects
010302 applied physics, Materials science, business.industry, Terahertz radiation, Transistor, General Physics and Astronomy, 02 engineering and technology, Electron, 021001 nanoscience & nanotechnology, 01 natural sciences, Instability, Spectral line, Gallium arsenide, law.invention, [SPI.TRON]Engineering Sciences [physics]/Electronics, chemistry.chemical_compound, chemistry, law, Ballistic conduction, 0103 physical sciences, Optoelectronics, 0210 nano-technology, business, ComputingMilieux_MISCELLANEOUS, Voltage
Abstract

Terahertz emission from InGaAs∕InAlAs lattice-matched high electron mobility transistors was observed. The emission appears in a threshold-like manner when the applied drain-to-source voltage UDS is larger than a threshold value UTH. The spectrum of the emitted signal consists of two maxima. The spectral position of the lower-frequency maximum (around 1 THz) is sensitive to UDS and UGS, while that of the higher frequency one (around 5 THz) is not. The lower-frequency maximum is interpreted as resulting from the Dyakonov–Shur instability of the gated two-dimensional electron fluid, while the higher frequency is supposed to result from current-driven plasma instability in the ungated part of the channel. The experimental results are confirmed by and discussed within Monte Carlo calculations of the high-frequency current noise spectra.

Published
2005
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19. Ballistic GaInAs/AlInAs devices technology and characterization at room temperature

Author

E. Pichonat, Y. Roelens, Alain Cappy, J. Mateos, Xavier Wallart, T. Gonzales, J.S. Galloo, Sylvain Bollaert, Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF), and Universidad de Salamanca

Subjects
Materials science, Nanolithography, Nanotechnology, 02 engineering and technology, Indium phosphide, Gallium arsenide, chemistry.chemical_compound, [SPI]Engineering Sciences [physics], Ballistic conduction, 0202 electrical engineering, electronic engineering, information engineering, business.industry, Temperature, Schottky diode, 020206 networking & telecommunications, Semiconductor device, Frequency, Bit rate, 021001 nanoscience & nanotechnology, Active devices, Characterization (materials science), Resists, Data processing, chemistry, Wet etching, Optoelectronics, 0210 nano-technology, business, Indium gallium arsenide, Hydrogen
Abstract

International audience; We have developed technology based on GaInAs/AlInAs for building ballistic devices working at room temperature. We first present here processes for passive and active devices (T-branch junctions (TBJs), Y-branch junctions (YBJs) and TBJs with Schottky gates. Then, we present DC characterization of TBJs to prove the ballistic behaviour and new results for YBJs.

Published
2004
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20. Nanoscaled double Y-Branch junction operating as room temperature RF to DC rectifier

Author

J.S. Galloo, E. Pichonat, Vincent Bayot, Rashmi, Isabelle Huynen, H. Boutry, Y. Roelens, Benoît Hackens, Sylvain Bollaert, Lukasz Bednarz, Alain Cappy, Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF), CeRMiN, Research Center in Micro and Nanoscopic Materials and Electronic Devices, and Université Catholique de Louvain = Catholic University of Louvain (UCL)

Subjects
Materials science, Electrons, 02 engineering and technology, 7. Clean energy, Capacitance, Gallium arsenide, Crosstalk, Degradation, [SPI]Engineering Sciences [physics], chemistry.chemical_compound, Radio frequency, Broadband, 0202 electrical engineering, electronic engineering, information engineering, Temperature measurement, Rectifiers, business.industry, Energy conversion efficiency, Equivalent circuits, Voltage, 020206 networking & telecommunications, 021001 nanoscience & nanotechnology, Coplanar waveguides, Electric variables measurement, chemistry, Nanoelectronics, Optoelectronics, Equivalent circuit, 0210 nano-technology, business, Hafnium
Abstract

International audience; Room temperature DC and broadband HF measurements of a double Y-branch junction are presented and discussed. Nonlinear DC characteristics of the devices at room temperature are observed and HF to DC conversion up to 20 GHz at room temperature is presented. Small-signal equivalent circuit of YBJ is proposed. The HF to DC conversion efficiency degradation is found to be due to parasitic crosstalk capacitance between the 2DEG access reservoirs of the device.

Published
2004
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21. Effects of substrate preparation on properties of YBaCuO thin films

Author

J.C. Carru, M. Achani, Maryline Guilloux-Viry, E. Caristan, Alain J. Kreisler, Annick F. Dégardin, X. Castel, A. Perrin, Y. Roelens, Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), and Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)

Subjects
Microwave surface resistance, Materials science, Annealing (metallurgy), Energy Engineering and Power Technology, 02 engineering and technology, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Electronic, Optical and Magnetic Materials, Microwave conductivity, Surface conductivity, 0103 physical sciences, Electrical and Electronic Engineering, Thin film, Composite material, 010306 general physics, 0210 nano-technology
Abstract

The influence of MgO substrate thermal annealing prior to YBaCuO deposition has been studied. An improvement in the crystalline quality as well as better critical temperature and microwave surface resistance values have been observed for films sputtered onto annealed (vs unannealed) substrates.

Published
2000
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22. Influence of the surface charge on the operation of ballistic T-branch junctions: a self-consistent model for Monte Carlo simulations.

Author

I I, J Mateos, T Gonz, D Pardo, J S Galloo, S Bollaert, Y Roelens, and A Cappy

Subjects
HETEROJUNCTIONS, MONTE Carlo method, ELECTRIC charge, CHARGE transfer
Abstract

We analyse the influence of the surface charge on the operation of ballistic T-branch junctions by means of a semi-classical 2D Monte Carlo simulator. We propose a new self-consistent model in which the local value of the surface charge is dynamically adjusted depending on the surrounding carrier density. The well-known parabolic behaviour of the central branch potential VCwhen biasing right and left branches in a push-pull fashion is found to be much influenced by the value of the surface charge in both the horizontal and vertical branches. With the help of experimental measurements performed in real devices, the influence of the width of the central branch on the values of VCand its relation to surface charge effects are also studied. [ABSTRACT FROM AUTHOR]

Published
2007

23. Room-temperature terahertz emission from nanometer field-effect transistors

Author

Andrey Shchepetov, Y. Roelens, Alain Cappy, Nina Dyakonova, C. Gaquiere, Erwan Morvan, Michel Dyakonov, M.A. Poisson, Wojciech Knap, Didier Theron, J. Lusakowskil, Sylvain Bollaert, A. El Fatimy, Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF), Groupe d'étude des semiconducteurs (GES), Centre National de la Recherche Scientifique (CNRS)-Université Montpellier 2 - Sciences et Techniques (UM2), Laboratoire de Physique Théorique et Astroparticules (LPTA), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Université Montpellier 2 - Sciences et Techniques (UM2)-Centre National de la Recherche Scientifique (CNRS)

Subjects
III-V semiconductors, Materials science, ndium compounds, Physics and Astronomy (miscellaneous), Terahertz radiation, Astrophysics::High Energy Astrophysical Phenomena, 02 engineering and technology, Radiation, 01 natural sciences, 7. Clean energy, Gallium arsenide, law.invention, Condensed Matter::Materials Science, chemistry.chemical_compound, law, 0103 physical sciences, 010306 general physics, Terahertz time-domain spectroscopy, 84.40.-x, 010302 applied physics, wide band gap semiconductors, business.industry, Transistor, Wide-bandgap semiconductor, submillimetre wave transistors, aluminium compounds, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, 021001 nanoscience & nanotechnology, high electron mobility transistors, 85.30.Tv – 84.40.-x, gallium arsenide, submillimetre wave generation PACS: 85.30.Tv, Nanoelectronics, chemistry, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Optoelectronics, Nanometre, Field-effect transistor, gallium compounds, 0210 nano-technology, business, Voltage
Abstract

International audience; Room-temperature generation of terahertz radiation in nanometer gate length InAlAs/InGaAs and AlGaN/GaN high-mobility transistors is reported. A well-defined source-drain voltage threshold for the emission exists, which depends on the gate bias. Spectral analysis of the emitted radiation is presented. The highest emission power emitted from a single device reached 0.1 µW.

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24. Plasma wave HEMTs for THz applications

Author

Andrey Shchepetov, A. Ei Fatimy, J. Lusakowski, Michel Dyakonov, Frederic Teppe, Sylvain Bollaert, Y. Roelens, Alain Cappy, Nina Dyakonova, Wojciech Knap, Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), and Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)

Subjects
010302 applied physics, Materials science, business.industry, Terahertz radiation, Waves in plasmas, Detector, Physics::Optics, Biasing, 02 engineering and technology, Plasma, High-electron-mobility transistor, 021001 nanoscience & nanotechnology, Plasma oscillation, 7. Clean energy, 01 natural sciences, Capacitance, 0103 physical sciences, Optoelectronics, 0210 nano-technology, business
Abstract

New THz chip solid-state detectors and sources are waited for many applications. The idea of new sources and detectors, based on the oscillations of bidimensional plasma, was theoretically and experimentally demonstrated. We present technological process of nanometric devices dedicated to THz emission. In this structure, a MIM gate-source capacitance is integrated to HEMT to achieve the boundary condition of plasma wave generation and to keep possible the gate biasing, necessary for frequency tuning. High electron mobility material like InAlAs/GaInAs heterostructure is used otherwise the plasma wave is dumped by electron scattering. Electrical and THz measurements are realized.

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25. 100 nm AlSb/InAs HEMT for ultra-low-power consumption, low-noise applications.

Author

Gardès C, Bagumako S, Desplanque L, Wichmann N, Bollaert S, Danneville F, Wallart X, and Roelens Y

Subjects
Electric Power Supplies trends, Electrons, Transistors, Electronic trends
Abstract

We report on high frequency (HF) and noise performances of AlSb/InAs high electron mobility transistor (HEMT) with 100 nm gate length at room temperature in low-power regime. Extrinsic cut-off frequencies fT/f max of 100/125 GHz together with minimum noise figure NF(min) = 0.5 dB and associated gain G(ass) = 12 dB at 12 GHz have been obtained at drain bias of only 80 mV, corresponding to 4 mW/mm DC power dissipation. This demonstrates the great ability of AlSb/InAs HEMT for high-frequency operation combined with low-noise performances in ultra-low-power regime.

Published
2014
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26. Evidence of surface charge effects in T-branch nanojunctions using microsecond-pulse testing.

Author

Iñiguez-de-la-Torre I, Mateos J, Roelens Y, Gardès C, Bollaert S, and González T

Abstract

The understanding of the influence of surface charge effects on the electrical properties of nanostructures is a key aspect for the forthcoming generations of electronic devices. In this paper, by using an ultrafast electrical pulse characterization technique, we report on the room-temperature time response of a T-branch nanojunction which allows us to identify the signature of surface states. Different pulse widths from 500 ns to 100 µs were applied to the device. For a given pulse width, the stem voltage is measured and compared with the DC result. The output value in the stem is found to depend on the pulse width and to be related to the characteristic charging time of the interface states. As expected, the results show that the well-known nonlinear response of T-branch junctions is more pronounced for long pulses, beyond such a characteristic time.

Published
2011
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27. Concurrent use of lamotrigine and electroconvulsive therapy.

Author

Sienaert P, Roelens Y, Demunter H, Vansteelandt K, Peuskens J, and Van Heeringen C

Subjects
Adult, Aged, Anticonvulsants therapeutic use, Combined Modality Therapy, Female, Humans, Lamotrigine, Male, Middle Aged, Retrospective Studies, Seizures drug therapy, Time Factors, Electroconvulsive Therapy, Seizures etiology, Seizures therapy, Triazines therapeutic use
Abstract

Objective: : To evaluate the effect of lamotrigine (LMT) on electroconvulsive therapy (ECT)-induced seizures., Methods: : Charts of all patients receiving LMT while undergoing an ECT course from July 2001 through May 2009 were reviewed. Apart from demographic variables, data collection consisted of diagnosis, indication for ECT, index or continuation ECT, electrode placement, stimulus dose, motor and electroencephalographic seizure duration, LMT dose, and number of restimulations. The stimulus dose and the seizure duration of ECT treatments with concurrent LMT (≥200 mg/d) were compared with the stimulus dose and seizure duration of ECT treatments without concurrent LMT., Results: : Lamotrigine was used by 19 patients (16 women, 3 men) during 289 treatment sessions. Eleven patients had ECT treatments with and without LMT, of which 8 were at a dosage of 200 mg/d or higher. Analyses did not reveal a significant difference in seizure duration and stimulus dose. Missed seizures, however, occurred more frequently during ECT treatments with concurrent LMT., Conclusions: : In all patients, seizures of adequate duration could be elicited. The combination was well tolerated. Therapeutic doses of LMT do not seem to have a clinically significant influence on the length of ECT-induced seizures nor on the stimulus dose.

Published
2011
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