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KNAP Wojciech
Organisme : CNRS
Directeur de Recherche (HDR)
Directeur(trice) de thèse de :
BUT D.,
Autre(s) thème(s) de recherche ou rattachement(s) : - Spectroscopie Térahertz
Wojciek.Knap
univ-montp2.fr
0467143217 (ou 4295)
Bureau: 14.1, Etg: 2, Bât: 21 - Site : Campus Triolet
Domaines de Recherche: - Physique/Matière Condensée/Science des matériaux
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Dernieres productions scientifiques :
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Ultrahigh sensitive terahertz detection by asymmetric dual-grating gate HEMT structure 
Auteur(s): KURITA Y., Ducournau G., Kobayashi K., Meziani Y., Popov V., KNAP W., Otsuji T.
Conference: International Workshop on Terahertz Science and Technology, OTST 2013 (Kyoto, JP, 2013)
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Terahertz detection using Si-SiGe MODFETs
Auteur(s): Meziani Y.m, Velazquez-perez J.e, COQUILLAT D., DIAKONOVA N., KNAP W., Grigelionis I, Garcia-garcia E, Fobelets K
Conference: Spanish Conference on Electron Devices (CDE), 2013 (Valladolid, ES, 2013-02-12)
Actes de conférence: Electron Devices (CDE), 2013 Spanish Conference on, vol. p.167 (2013)
Ref HAL: hal-00816915_v1
DOI: 10.1109/CDE.2013.6481369
Résumé: We report on resonant and non-resonant (broad-band) detection of terahertz (THz) radiation using Strained-Si MODFETs. The devices were excited at room temperature by two types of THz sources at 0.292 THz and at 1.5 THz. Non-resonant response with maxima around the threshold voltage was observed. Shubnikov-de Haas along with photoresponse measurements were performed simultaneously to demonstrate that the observed response is related to the plasma waves oscillation in the channel. The device was cooled down to 4.2 K and resonant signature could be observed.
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Sub-threshold Attenuation of Terahertz Detection by Asymmetric Dual-Grating Gate HEMT Structures
Auteur(s): COQUILLAT D. , Kurita K, Kobayashi K, TEPPE F., DIAKONOVA N., BUT D., Tohme L, Nouvel P, Blin S, Torres J, Pénarier A, Otsuji T, KNAP W.
Conference: International Workshop on Optical Terahertz Science and Technology (Kyoto, JP, 2013-04-01)
Actes de conférence: Extended Abstracts OTST 2013, vol. p.217 (2013)
Ref HAL: hal-00816663_v1
Résumé: The nonresonant detection of terahertz detectors based on asymmetric dual-grating-gate (A-DGG) high electron mobility transistors has been reported at both terahertz and sub-terahertz frequencies in several papers; but its behavior could not be fully understood in the range of the gate voltages close to and below the threshold voltage Vth. Two different contributions can attenuate the photoresponse u in the sub-threshold voltage region. The model developed in Ref. 3 showed that the gate leakage current suppresses the detector terahertz photoresponse in the sub-threshold region, leading to a nonresonant maximum in photoresponse versus gate dependence. While, in the model of Ref. 4, the detector loading effects were considered as responsible for the signal drop in the sub-threshold range. These effects are related to the voltage divider formed by input impedance of the measurement apparatus and the channel resistance of the detector which is exponentially increasing below threshold [4]. In the framework of the ANR-JST WITH project, we performed detailed studies of both the voltage u and the current i photoresponse of A-DGG devices. The photoresponse i was determined using the transfer characteristics measured with and without applied terahertz radiation. The measurements were carried out as a function of gate voltage and temperature (4 - 300 K), for incoming radiation frequencies of 292 and 655 GHz. As a result, we show that both effects are important and their relative contributions depend on gate voltage and temperature. We determine the separate contributions of the gate leakage current and the loading effect to the terahertz rectification signal in the sub-threshold region.
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Terahertz Rectification as Probe of quantum phenomena in Graphene
Auteur(s): COQUILLAT D., DIAKONOVA N., Ribeiro R, Goiran M, Poumirol J.M., Escoffier W., Raquet B, BUT D., BUZATU P., CONSEJO C., TEPPE F., KNAP W.
Conference: International Workshop on Optical Terahertz Science and Technology (Kyoto, JP, 2013-04-01)
Actes de conférence: Extended Abstracts OTST 2013, vol. p.144 (2013)
Ref HAL: hal-00816650_v1
Résumé: In this work, we undertake detailed studies of the mesoscopic rectification of an ac current at THz frequency induced by the incoming radiation for back-gated graphene field effect transistors. Using THz detection as a probe, we explore the nonlinear behavior of the quantum fluctuations and weak localization.
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Room-temperature nanowire terahertz photodetectors
Auteur(s): Romeo Lorenzo, COQUILLAT D., Viti Leonardo, Ercolani Daniele, Sorba Lucia, KNAP W., Tredicucci Alessandro, Vitiello Miriam
Conference: Quantum Sensing and Nanophotonic Devices X (, US, 2013-02-02)
Actes de conférence: Proceedings SPIE, 8631, Quantum Sensing and Nanophotonic Devices X, vol. 8631 p.86312E (2013)
Ref HAL: hal-00816617_v1
DOI: 10.1117/12.2004193
Résumé: Semiconductor nanowires (NWs) represent an ideal building block for implementing rectifying diodes or plasma wave detectors that could operate well into the THz, thanks to the typical attofarad-order capacitance. Despite the strong effort in developing these nanostructures for a new generation of complementary metal-oxide semi conductors (CMOS), memory and photonic devices, their potential as radiation sensors into the Terahertz is just starting to be explored. We report on the development of NW-based field effect transistors operating as high sensitivity THz detectors in the 0.3 - 2.8 THz range. By feeding the radiation field of either an electronic THz source or a quantum cascade laser (QCL) at the gate-source electrodes by means of a wide band dipole antenna, we measured a photovoltage signal corresponding to responsivity values up to 100 V IW, with impressive noise equivalent power levels < 6 x 10-11W/Hz at room temperature and a > 300kHz modulation bandwidth. The potential scalability to even higher frequencies and the technological feasibility of realizing multi-pixel arrays coupled with QCL sources make the proposed technology highly competitive for a future generation of THz detection systems.
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