Records |
Author |
Smirnov, K. V.; Ptitsina, N. G.; Vakhtomin, Y. B.; Verevkin, A. A.; Gol’tsman, G. N.; Gershenzon, E. M. |
Title |
Energy relaxation of two-dimensional electrons in the quantum Hall effect regime |
Type |
Journal Article |
Year |
2000 |
Publication |
JETP Lett. |
Abbreviated Journal |
JETP Lett. |
Volume |
71 |
Issue |
1 |
Pages |
31-34 |
Keywords |
2DEG, GaAs/AlGaAs heterostructures |
Abstract |
The mm-wave spectroscopy with high temporal resolution is used to measure the energy relaxation times τe of 2D electrons in GaAs/AlGaAs heterostructures in magnetic fields B=0–4 T under quasi-equilibrium conditions at T=4.2 K. With increasing B, a considerable increase in τe from 0.9 to 25 ns is observed. For high B and low values of the filling factor ν, the energy relaxation rate τ −1e oscillates. The depth of these oscillations and the positions of maxima depend on the filling factor ν. For ν>5, the relaxation rate τ −1e is maximum when the Fermi level lies in the region of the localized states between the Landau levels. For lower values of ν, the relaxation rate is maximum at half-integer values of τ −1e when the Fermi level is coincident with the Landau level. The characteristic features of the dependence τ −1e (B) are explained by different contributions of the intralevel and interlevel electron-phonon transitions to the process of the energy relaxation of 2D electrons. |
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0021-3640 |
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http://jetpletters.ru/ps/899/article_13838.shtml (“Энергетическая релаксация двумерных электронов в области квантового эффекта Холла”) |
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Call Number |
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Serial |
1559 |
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Author |
Gerecht, E.; Musante, C. F.; Zhuang, Y.; Yngvesson, K. S.; Gol’tsman, G. N.; Voronov, B. M.; Gershenzon, E. M. |
Title |
NbN hot electron bolometric mixerss—a new technology for low-noise THz receivers |
Type |
Journal Article |
Year |
1999 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
Volume |
47 |
Issue |
12 |
Pages |
2519-2527 |
Keywords |
NbN HEB mixers |
Abstract |
New advances in hot electron bolometer (HEB) mixers have recently resulted in record-low receiver noise temperatures at terahertz frequencies. We have developed quasi-optically coupled NbN HEB mixers and measured noise temperatures up to 2.24 THz, as described in this paper. We project the anticipated future performance of such receivers to have even lower noise temperature and local-oscillator power requirement as well as wider gain and noise bandwidths. We introduce a proposal for integrated focal plane arrays of HEB mixers that will further increase the detection speed of terahertz systems. |
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ISSN |
1557-9670 |
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no |
Call Number |
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Serial |
1560 |
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Author |
Gol’tsman, G. N.; Gershenzon, E. M. |
Title |
Phonon-cooled hot-electron bolometric mixer: overview of recent results |
Type |
Journal Article |
Year |
1999 |
Publication |
Appl. Supercond. |
Abbreviated Journal |
Appl. Supercond. |
Volume |
6 |
Issue |
10-12 |
Pages |
649-655 |
Keywords |
NbN HEB mixers |
Abstract |
The paper presents an overview of recent results for NbN phonon-cooled hot electron bolometric (HEB) mixers. The noise temperature of the receivers based on both quasioptical and waveguide versions of HEB mixer has crossed the level of 1 K·GHz−1 at 430 GHz (410 K) and 600–650 GHz (480 K) and is close to this level at 820 GHz (1100 K) and 900 GHz (980 K). The gain bandwidth measured for quasioptical HEB mixer at 620 GHz reached 4 GHz and the noise temperature bandwidth was almost 8 GHz. Local oscillator power requirements are about 1 μW for mixers made by photolithography and are about 100 nW for mixers made by e-beam lithography. The studies in terahertz receivers based on HEB superconducting mixers now present a dynamic, rapidly developing field. |
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0964-1807 |
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1564 |
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Author |
Verevkin, A. A.; Ptitsina, N. G.; Smirnov, K. V.; Voronov, B. M.; Gol’tsman, G. N.; Gershenson, E. M.; Yngvesson, K. S. |
Title |
Multiple Andreev reflection in hybrid AlGaAs/GaAs structures with superconducting NbN contacts |
Type |
Journal Article |
Year |
1999 |
Publication |
Semicond. |
Abbreviated Journal |
Semicond. |
Volume |
33 |
Issue |
5 |
Pages |
551-554 |
Keywords |
2DEG, AlGaAs/GaAs heterostructures |
Abstract |
The conductivity of hybrid microstructures with superconducting contacts made of niobium nitride to a semiconductor with a two-dimensional electron gas in a AlGaAs/GaAs heterostructure has been investigated. Distinctive features of the behavior of the conductivity indicate the presence of multiple Andreev reflection at scattering centers in the normal region near the superconductor-semiconductor boundary. |
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Edition |
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ISSN |
1063-7826 |
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no |
Call Number |
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Serial |
1571 |
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Author |
Men’shchikov, E. M.; Gogidze, I. G.; Sergeev, A. V.; Elant’ev, A. I.; Kuminov, P. B.; Gol’tsman, G. N.; Gershenzon, E. M. |
Title |
Superconducting fast detector based on the nonequilibrium inductance response of a film of niobium nitride |
Type |
Journal Article |
Year |
1997 |
Publication |
Tech. Phys. Lett. |
Abbreviated Journal |
Tech. Phys. Lett. |
Volume |
23 |
Issue |
6 |
Pages |
486-488 |
Keywords |
NbN KID |
Abstract |
A new type of fast detector is proposed, whose operation is based on the variation of the kinetic inductance of a superconducting film caused by nonequilibrium quasiparticles created by the electromagnetic radiation. The speed of the detector is determined by the rate of multiplication of photo-excited quasiparticles, and is nearly independent of the temperature, being less than 1 ps for NbN. Models based on the Owen-Scalapino scheme give a good description of the experimentally determined dependence of the power-voltage sensitivity of the detector on the modulation frequency. The lifetime of the quasiparticles is determined, and it is shown that the reabsorption of nonequilibrium phonons by the condensate has a substantial effect even in ultrathin NbN films 5 nm thick, and results in the maximum possible quantum yield. A low concentration of equilibrium quasiparticles and a high quantum yield result in a detectivity D*=1012 W−1·Hz1/2 at a temperature T=4.2 K and D*=1016 W−1·cm· Hz1/2 at T=1.6 K. |
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1063-7850 |
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no |
Call Number |
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Serial |
1593 |
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