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Physique Appliquée
(71) Production(s) de l'année 2016
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Indirect excitons in AlGaN/GaN polar quantum wells.
Auteur(s): Vladimirova M., Jouault B., Fedichkin F., Guillet T., Brimont C., Valvin P., Bretagnon T., Grandjean N., Lefebvre P.
Conférence invité: 17th International Conference on Physics of Light-Matter Coupling in Nanostructures – PLMCN17. (Nara, JP, 2016-03-28)
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Terahertz Imaging with GaAs and GaN Plasma Field Effect Transistors Detectors
Auteur(s): Knap W., But D., Diakonova N., Coquillat D., Teppe F., Suszek Jaroslaw, Siemion Agnieszka M., Sypek Maciej, Szkudlarek Krzesimir, Cywinski Grzegorz, Yahniuk Ivan
Conference: PROCEEDINGS OF THE 23RD INTERNATIONAL CONFERENCE ON MIXED DESIGN OF INTEGRATED CIRCUITS AND SYSTEMS (Lodz, PL, 2016-06-23)
Ref HAL: hal-01380958_v1
WoS: WOS:000383221700011
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3 Citations
Résumé: An overview of recent results concerning THz detection related to plasma nonlinearities in nanometer field effect transistors is presented. In particular, the research on the dynamic range of these detectors is described and two different technologies GaAs and GaN are compared. As a conclusion, we will show first real world applications of the plasma field effect transistors based THz detectors: demonstrators of the imagers (cameras and linear scanners) developed for fast postal security and for nondestructive industrial quality control.
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Two-dimensional plasmons in lateral carbon nanotube network structures and their effect on the terahertz radiation detection
Auteur(s): Ryzhii V., Otsuji T., Ryzhii M., Leiman V. G., Fedorov G., Goltzman G. N., Gayduchenko I. A., Titova N., Coquillat D., But D., Knap W., Mitin V., Shur M. S.
(Article) Publié:
Journal Of Applied Physics, vol. 120 p.044501 (2016)
Texte intégral en Openaccess :
Ref HAL: hal-01375368_v1
DOI: 10.1063/1.4959215
WoS: WOS:000382405400030
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11 Citations
Résumé: We consider the carrier transport and plasmonic phenomena in the lateral carbon nanotube (CNT) networks forming the device channel with asymmetric electrodes. One electrode is the Ohmic contact to the CNT network and the other contact is the Schottky contact. These structures can serve as detectors of the terahertz (THz) radiation. We develop the device model for collective response of the lateral CNT networks which comprise a mixture of randomly oriented semiconductor CNTs (s-CNTs) and quasi-metal CNTs (m-CNTs). The proposed model includes the concept of the collective two-dimensional (2D) plasmons in relatively dense networks of randomly oriented CNTs (CNT “felt”) and predicts the detector responsivity spectral characteristics exhibiting sharp resonant peaks at the signal frequencies corresponding to the 2D plasmonic resonances. The detection mechanism is the rectification of the ac current due the nonlinearity of the Schottky contact current-voltage characteristics under the conditions of a strong enhancement of the potential drop at this contact associated with the plasmon excitation. The detector responsivity depends on the fractions of the s- and m-CNTs. The burning of the near-contact regions of the m-CNTs or destruction of these CNTs leads to a marked increase in the responsivity in agreement with our experimental data. The resonant THz detectors with sufficiently dense lateral CNT networks can compete and surpass other THz detectors using plasmonic effects at room temperatures.
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Nuclear spin warm up in bulk n-GaAs
Auteur(s): Kotur M., Dzhioev R. I., Vladimirova M., Jouault B., Korenev V. L., Kavokin K. V.
(Article) Publié:
Physical Review B, vol. 94 p.081201 (2016)
Texte intégral en Openaccess :
Ref HAL: hal-01393714_v1
DOI: 10.1103/PhysRevB.94.081201
WoS: WOS:000381889700002
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10 Citations
Résumé: We show that the spin-lattice relaxation in n-type insulating GaAs is dramatically accelerated at low magnetic fields. The origin of this effect, which cannot be explained in terms of well-known diffusion-limited hyperfine relaxation, is found in the quadrupole relaxation, induced by fluctuating donor charges. Therefore, quadrupole relaxation, which governs low field nuclear spin relaxation in semiconductor quantum dots, but was so far supposed to be harmless to bulk nuclei spins in the absence of optical pumping, can be studied and harnessed in the much simpler model environment of n-GaAs bulk crystal.
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Terahertz imaging of Landau levels in HgTe-based topological insulators
Auteur(s): Kadykov A., Torres Jeremie, Krishtopenko S., Consejo C., Ruffenach S., Marcinkiewicz M., But D., Knap W., Morozov Sergey V., Gavrilenko Vladimir I., Mikhailov Nikolai N., Dvoretsky Sergey A., Teppe F.
(Article) Publié:
Applied Physics Letters, vol. 108 p.262102 (2016)
Ref HAL: hal-01358769_v1
DOI: 10.1063/1.4955018
WoS: WOS:000379178200019
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11 Citations
Résumé: We report on sub-terahertz photoconductivity under the magnetic field of a two dimensional topologicalinsulator based on HgTe quantum wells. We perform a detailed visualization of Landau levelsby means of photoconductivity measured at different gate voltages. This technique allows oneto determine a critical magnetic field, corresponding to topological phase transition from invertedto normal band structure, even in almost gapless samples. The comparison with realistic calculationsof Landau levels reveals a smaller role of bulk inversion asymmetry in HgTe quantum wellsthan it was assumed previously.
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Room-Temperature Transport of Indirect Excitons in (Al,Ga)N/GaN Quantum Wells
Auteur(s): Fedichkin F., Guillet T., Valvin P., Jouault B., Brimont C., Bretagnon T., Lahourcade L., Grandjean N., Lefebvre P., Vladimirova M.
(Article) Publié:
Physical Review Applied, vol. 6 p.014011 (2016)
Texte intégral en Openaccess :
Ref HAL: hal-01353893_v2
DOI: 10.1103/PhysRevApplied.6.014011
WoS: WOS:000380125900001
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15 Citations
Résumé: We report on the exciton propagation in polar ðAl; GaÞN=GaN quantum wells over several micrometers and up to room temperature. The key ingredient to achieve this result is the crystalline quality of GaN quantum wells grown on GaN substrate that limits nonradiative recombination. From the comparison of the spatial and temporal dynamics of photoluminescence, we conclude that the propagation of excitons under continuous-wave excitation is assisted by efficient screening of the in-plane disorder. Modeling within drift-diffusion formalism corroborates this conclusion and suggests that exciton propagation is still limited by the exciton scattering on defects rather than by exciton-exciton scattering so that improving interface quality can boost exciton transport further. Our results pave the way towards room-temperature excitonic devices based on gate-controlled exciton transport in wide-band-gap polar heterostructures.
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Heterostructured hBN-BP-hBN Nanodetectors at Terahertz Frequencies.
Auteur(s): Viti Leonardo, Hu Jin, Coquillat D., Politano Antonio, Consejo C., Knap W., Vitiello Miriam s
(Article) Publié:
Advanced Materials, vol. p.1 (2016)
PMID 27315585
DOI: 10.1002/adma.201601736
WoS: 000383778700006
54 Citations
Résumé: By reassembling the thin isolated atomic planes of hexagonal borum nitride (hBN) with a few layer phosphorene (black phosphorus BP), hBN/BP/hBN heterostructures were mechanically stacked to devise high efficiency THz photodetectors operating in the 0.3-0.65 THz range, from 4K to 300K, with a record signal-to-noise ratio of 20000.
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