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Author Verevkin, A. A.; Ptitsina, N. G.; Chulcova, G. M.; Gol'Tsman, G. N.; Gershenzon, E. M.; Yngvesson, K. S.
Title (down) Determination of the limiting mobility of a two-dimensional electron gas in AlxGa1-xAs/GaAs heterostructures and direct measurement of the energy relaxation time Type Journal Article
Year 1996 Publication Phys. Rev. B Condens. Matter. Abbreviated Journal Phys. Rev. B Condens. Matter.
Volume 53 Issue 12 Pages R7592-R7595
Keywords 2DEG, AlGaAs/GaAs heterostructures
Abstract We present results for a method to measure directly the energy relaxation time (τe) for electrons in a single AlxGa1−xAs/GaAs heterojunction; measurements were performed from 1.6 to 15 K under quasiequilibrium conditions. We find τeαT−1 below 4 K, and τe independent of T above 4 K. We have also measured the energy-loss rate, ⟨Q⟩, by the Shubnikov-de Haas technique, and find ⟨Q⟩α(T3e−T3) for T<~4.2 K; Te is the electron temperature. The values and temperature dependence of τe and ⟨Q⟩ for T<4 K agree with calculations based on piezoelectric and deformation potential acoustic phonon scattering. At 4.2 K, we can also estimate the momentum relaxation time, τm, from our measured τe. This leads to a preliminary estimate of the phonon-limited mobility at 4.2 K of μ=3×107 cm2/Vs (ns=4.2×1011 cm−2), which agrees well with published numerical calculations, as well as with an earlier indirect estimate based on measurements on a sample with much higher mobility.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0163-1829 ISBN Medium
Area Expedition Conference
Notes PMID:9982274 Approved no
Call Number Serial 1612
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Author Verevkin, A.; Zhang, J.; Sobolewski, Roman; Lipatov, A.; Okunev, O.; Chulkova, G.; Korneev, A.; Smirnov, K.; Gol'tsman, G. N.; Semenov, A.
Title (down) Detection efficiency of large-active-area NbN single-photon superconducting detectors in the ultraviolet to near-infrared range Type Journal Article
Year 2002 Publication Appl. Phys. Lett. Abbreviated Journal
Volume 80 Issue 25 Pages 4687-4689
Keywords NbN SSPD, SNSPD, QE
Abstract We report our studies on spectral sensitivity of meander-type, superconducting NbN thin-film single-photon detectors (SPDs), characterized by GHz counting rates of visible and near-infrared photons and negligible dark counts. Our SPDs exhibit experimentally determined quantum efficiencies ranging from ∼0.2% at the 1.55 μm wavelength to ∼70% at 0.4 μm. Spectral dependences of the detection efficiency (DE) at the 0.4 to 3.0-μm-wavelength range are presented. The exponential character of the DE dependence on wavelength, as well as its dependence versus bias current, is qualitatively explained in terms of superconducting fluctuations in our ultrathin, submicron-width superconducting stripes. The DE values of large-active-area NbN SPDs in the visible range are high enough for modern quantum communications.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
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ISSN ISBN Medium
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Notes Approved no
Call Number Serial 331
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Author Shangina, E. L.; Smirnov, K. V.; Morozov, D. V.; Kovalyuk, V. V.; Gol’tsman, G. N.; Verevkin, A. A.; Toropov, A. I.
Title (down) Concentration dependence of the intermediate frequency bandwidth of submillimeter heterodyne AlGaAs/GaAs nanostructures Type Journal Article
Year 2010 Publication Bull. Russ. Acad. Sci. Phys. Abbreviated Journal Bull. Russ. Acad. Sci. Phys.
Volume 74 Issue 1 Pages 100-102
Keywords 2DEG AlGaAs/GaAs heterostructures, THz heterodyne detectors, IF bandwidth
Abstract The concentration dependence of the intermediate frequency bandwidth of heterodyne AlGaAs/GaAs detectors with 2D electron gas is measured using submillimeter spectroscopy with high time resolution at T= 4.2 K. The intermediate frequency bandwidth f3dBfalls from 245 to 145 MHz with increasing concentration of 2D electrons n s = (1.6-6.6) × 10[su11] cm-2. The dependence f3dB ≈ n s – 0.04±is observed in the studied concentration range; this dependence is determined by electron scattering by the deformation potential of acoustic phonons and piezoelectric scattering.
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Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1062-8738 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1217
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Author Shangina, E. L.; Smirnov, K. V.; Morozov, D. V.; Kovalyuk, V. V.; Goltsman, G. N.; Verevkin, A. A.; Toropov, A. I.; Mauskopf, P.
Title (down) Concentration dependence of energy relaxation time in AlGaAs/GaAs heterojunctions: direct measurements Type Journal Article
Year 2011 Publication Semicond. Sci. Technol. Abbreviated Journal Semicond. Sci. Technol.
Volume 26 Issue 2 Pages 025013
Keywords AlGaAs/GaAs heterojunctions
Abstract We present measurements of the energy relaxation time, τε, of electrons in a single heterojunction in a quasi-equilibrium state using microwave time-resolved spectroscopy at 4.2 K. We find the relaxation time has a power-law dependence on the carrier density of the two-dimensional electron gas, τε∝nγs with γ = 0.40 ± 0.02 for values of the carrier density, ns, from 1.6 × 1011 to 6.6 × 1011cm−2. The results are in good agreement with predictions taking into account the scattering of the carriers by both piezoelectric and deformation potential acoustic phonons. We compare these results with indirect measurements of the energy relaxation time from energy loss measurements involving Joule heating of the electron gas.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0268-1242 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1215
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Author Lipatov, A.; Okunev, O.; Smirnov, K.; Chulkova, G.; Korneev, A.; Kouminov, P.; Gol'tsman, G.; Zhang, J.; Slysz, W.; Verevkin, A.; Sobolewski, R.
Title (down) An ultrafast NbN hot-electron single-photon detector for electronic applications Type Journal Article
Year 2002 Publication Supercond. Sci. Technol. Abbreviated Journal Supercond. Sci. Technol.
Volume 15 Issue 12 Pages 1689-1692
Keywords NbN SSPD, SNSPD, QE, jitter, dark counts
Abstract We present the latest generation of our superconducting single-photon detector (SPD), which can work from ultraviolet to mid-infrared optical radiation wavelengths. The detector combines a high speed of operation and low jitter with high quantum efficiency (QE) and very low dark count level. The technology enhancement allows us to produce ultrathin (3.5 nm thick) structures that demonstrate QE hundreds of times better, at 1.55 μm, than previous 10 nm thick SPDs. The best, 10 × 10 μm2, SPDs demonstrate QE up to 5% at 1.55 μm and up to 11% at 0.86 μm. The intrinsic detector QE, normalized to the film absorption coefficient, reaches 100% at bias currents above 0.9 Ic for photons with wavelengths shorter than 1.3 μm.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0953-2048 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1533
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