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Author Schwaab, G. W.; Hübers, H.-W.; Schubert, J.; Erichsen, Patrik; Gol'tsman, G.; Semenov, A.; Verevkin, A.; Cherednichenko, S.; Gershenzon, E. url  openurl
  Title A high resolution spectrometer for the investigation of molecular structures in the THZ range Type Conference Article
  Year 1999 Publication Proc. 10th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 10th Int. Symp. Space Terahertz Technol.  
  Volume Issue Pages 530-538  
  Keywords antireflection coatings, dielectric mirrors  
  Abstract A status report on the design study of a novel tunable far-infrared (TuFTR) spectrometer for the investigation of the structure of weakly bound molecular complexes is given. The goal is a sensitive TuFIR spectrometer with full frequency coverage from 1-6 THz. To hit the goal, advanced sources (e.g. p-Ge lasers) and detectors (e.g. superconducting hot electron bolometric (HEB) mixers) shall be employed to extend the technique of cavity ringdown spectroscopy, that is currently used at optical and infrared frequencies to the FIR spectral range. Critical for such a system are high-Q resonators that still allow good optical coupling, and wideband antireflection coatings to increase detector sensitivity and decrease optical path losses. 2 nd order effective media theory and an iterative multilayer algorithm have been employed to design wideband antireflection coatings for dielectrics with large dielectric constants like Ge or Si. Taking into account 6 layers, for Si bandwidths of 100% of the center frequency could be obtained with power reflectivities below 1% for both polarizations simultaneously. Wideband dielectric mirrors including absorption losses were also studied yielding a bandwidth of about 50% with reflectivities larger than 99.5%.  
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  Notes Approved no  
  Call Number Serial 1577  
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Author Svechnikov, S.; Verevkin, A.; Voronov, B.; Menschikov, E.; Gershenzon, E.; Gol'tsman, G. url  openurl
  Title Quasioptical phonon-cooled NbN hot electron bolometer mixers at 0.5-1.1 THz Type Conference Article
  Year 1998 Publication Proc. 9th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 9th Int. Symp. Space Terahertz Technol.  
  Volume Issue Pages 45-51  
  Keywords NbN HEB mixers  
  Abstract The noise performance of a receiver incorporating spiral antenna coupled NbN phonon-cooled superconducting hot electron bolometric mixer is measured from 450 GHz to 1200 GHz. The mixer element is thin (thickness nm) NbN 1.5 pm wide and 0.2 i.um long film fabricated by lift-off e-beam lithography on high-resistive silicon substrate. The noise of the receiver temperature is 1000 K at 800-900 GHz, 1200 K at 950 GHz, and 1600 K at 1.08 THz. The required (absorbed) local-oscillator power is —20 nW.  
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  Area Expedition (up) Conference  
  Notes Approved no  
  Call Number Serial 1586  
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Author Verevkin, A. A.; Ptitsina, N. G.; Smirnov, K. V.; Goltsman, G. N.; Gershenson, E. M.; Yngvesson, K. S. url  openurl
  Title Direct measurements of electron energy relaxation times at an AlGaAs/GaAs heterointerface in the optical phonon scattering range Type Conference Article
  Year 1997 Publication Proc. 4-th Int. Semicond. Device Research Symp. Abbreviated Journal Proc. 4-th Int. Semicond. Device Research Symp.  
  Volume Issue Pages 55-58  
  Keywords 2DEG, AlGaAs/GaAs heterostructures  
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  Area Expedition (up) Conference  
  Notes Approved no  
  Call Number Serial 1602  
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Author Verevkin, A. A.; Ptitsina, N. G.; Smirnov, K. V.; Gol'tsman, G. N.; Voronov, B. M.; Gershenzon, E. M.; Yngvesson, K. S. url  openurl
  Title Hot electron bolometer detectors and mixers based on a superconducting-two-dimensional electron gas-superconductor structure Type Conference Article
  Year 1997 Publication Proc. 4-th Int. Semicond. Device Research Symp. Abbreviated Journal Proc. 4-th Int. Semicond. Device Research Symp.  
  Volume Issue Pages 163-166  
  Keywords S-2DEG-S HEB mixers, detectors, AlGaAs/GaAs heterostructures, NbN  
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  Area Expedition (up) Conference  
  Notes Approved no  
  Call Number Serial 1603  
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Author Verevkin, A. A.; Ptitsina, N. G.; Smirnov, K. V.; Gol’tsman, G. N.; Gershenzon, E. M.; Ingvesson, K. S. url  doi
openurl 
  Title Direct measurements of energy relaxation times on an AlGaAs/GaAs heterointerface in the range 4.2–50 K Type Journal Article
  Year 1996 Publication JETP Lett. Abbreviated Journal JETP Lett.  
  Volume 64 Issue 5 Pages 404-409  
  Keywords 2DEG, AlGaAs/GaAs heterostructures  
  Abstract The temperature dependence of the energy relaxation time τe (T) of a two-dimensional electron gas at an AlGaAs/GaAs heterointerface is measured under quasiequilibrium conditions in the region of the transition from scattering by acoustic phonons to scattering with the participation of optical phonons. The temperature interval of constant τe, where scattering by the deformation potential predominates, is determined. In the preceding, low-temperature region, where piezoacoustic and deformation-potential-induced scattering processes coexist, τ e decreases slowly with increasing temperature. Optical phonons start to participate in the scattering processes at T∼25 K (the characteristic phonon lifetime was equal to τLOτ4.5 ps). The energy losses calculated from the τe data in a model with an effective nonequilibrium electron temperature agree with the published data obtained under strong heating conditions.  
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  ISSN 0021-3640 ISBN Medium  
  Area Expedition (up) Conference  
  Notes http://jetpletters.ru/ps/981/article_14955.shtml (“Прямые измерения времен энергетической релаксации на гетерогранице AlGaAs/GaAs в диапазоне 4.2 – 50 К”) Approved no  
  Call Number Serial 1608  
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Author Verevkin, A. A.; Ptitsina, N. G.; Chulcova, G. M.; Gol'tsman, G. N.; Gershenzon, E. M.; Yngvesson, K. S. url  doi
openurl 
  Title Direct measurements of energy relaxation time of electrons in AlGaAs/GaAs heterostructures under quasi-equilibrium conditions Type Journal Article
  Year 1996 Publication Surface Science Abbreviated Journal Surface Science  
  Volume 361-362 Issue Pages 569-573  
  Keywords 2DEG, AlGaAs/GaAs heterostructures  
  Abstract For the first time, results are presented of a direct measurement of the energy relaxation time τε of 2D electrons in an AlGaAs/GaAs heterojunction at T = 1 and 5–20 K. A weak temperature dependence of τε for the T > 4K range and a linear temperature dependence of the reciprocal of τε for T < 4K have been observed. The linear dependence τε−1 ≈ T in the Bloch-Gruneisen regime is direct evidence of the predominance of the piezo-electric mechanism of electron-phonon interaction in non-elastic electron scattering processes. The values of τε in this regime are in very good agreement with the results of the Karpus theory. At higher temperatures, where the deformation-potential scattering becomes noticeable, a substantial disagreement between the experimental data and the theoretical results is observed.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0039-6028 ISBN Medium  
  Area Expedition (up) Conference  
  Notes Approved no  
  Call Number Serial 1609  
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Author Verevkin, A. A.; Ptitsina, N. G.; Chulcova, G. M.; Gol'Tsman, G. N.; Gershenzon, E. M.; Yngvesson, K. S. url  doi
openurl 
  Title 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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  Series Volume Series Issue Edition  
  ISSN 0163-1829 ISBN Medium  
  Area Expedition (up) Conference  
  Notes PMID:9982274 Approved no  
  Call Number Serial 1612  
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Author Verevkin, A. I.; Ptitsina, N. G.; Chulkova, G. M.; Gol'tsman, G. N.; Gershenzon, E. M.; Yngvesson, K. S. url  openurl
  Title Electron energy relaxation in a 2D channel in AlGaAs-GaAs heterostructures under quasiequilibrium conditions at low temperatures Type Journal Article
  Year 1995 Publication JETP Lett. Abbreviated Journal JETP Lett.  
  Volume 61 Issue 7 Pages 591-595  
  Keywords 2DEG, AlGaAs/GaAs heterostructures  
  Abstract The energy relaxation time of 2D electrons, Te, has been measured under quasiequilibrium conditions in AlGaAs—GaAs heterojunctions over the temperature range T= 1.5—20 K. At T> 4 K, Te depends only weakly on the temperature, while at T< 4 K 7;'(T) there is a dependence fr; lNT. A linear dependence 7: 1 (T) in the Bloch—-Grfineisen temperature region (T< 5 K) is unambiguous evidence that a piezoacoustic mechanism of an electron—phonon interaction is predominant in the inelastic scattering of electrons. The values of T6 in this temperature range agree very accurately with theoretical results reported by Karpus [Sov. Phys. Semicond. 22 (1988)]. At higher temperatures, where scat—tering by deformation acoustic phonons becomes substantial, there is a significant discrepancy between the experimental and theoretical re-sults.  
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  Notes Approved no  
  Call Number Serial 1624  
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Author Zhang, J.; Verevkin, A.; Slysz, W.; Chulkova, G.; Korneev, A.; Lipatov, A.; Okunev, O.; Gol’tsman, G. N.; Sobolewski, Roman url  doi
openurl 
  Title Time-resolved characterization of NbN superconducting single-photon optical detectors Type Conference Article
  Year 2017 Publication Proc. SPIE Abbreviated Journal Proc. SPIE  
  Volume 10313 Issue Pages 103130F (1 to 3)  
  Keywords NbN SSPD, SNSPD  
  Abstract NbN superconducting single-photon detectors (SSPDs) are very promising devices for their picosecond response time, high intrinsic quantum efficiency, and high signal-to-noise ratio within the radiation wavelength from ultraviolet to near infrared (0.4 gm to 3 gm) [1-3]. The single photon counting property of NbN SSPDs have been investigated thoroughly and a model of hotspot formation has been introduced to explain the physics of the photon- counting mechanism [4-6]. At high incident flux density (many-photon pulses), there are, of course, a large number of hotspots simultaneously formed in the superconducting stripe. If these hotspots overlap with each other across the width w of the stripe, a resistive barrier is formed instantly and a voltage signal can be generated. We assume here that the stripe thickness d is less than the electron diffusion length, so the hotspot region can be considered uniform. On the other hand, when the photon flux is so low that on average only one hotspot is formed across w at a given time, the formation of the resistive barrier will be realized only when the supercurrent at sidewalks surpasses the critical current (jr) of the superconducting stripe [1]. In the latter situation, the formation of the resistive barrier is associated with the phase-slip center (PSC) development. The effect of PSCs on the suppression of superconductivity in nanowires has been discussed very recently [8, 9] and is the subject of great interest.  
  Address  
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  Publisher SPIE Place of Publication Editor Armitage, J. C.  
  Language Summary Language Original Title  
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  Area Expedition (up) Conference Opto-Canada: SPIE Regional Meeting on Optoelectronics, Photonics, and Imaging, 2002, Ottawa, Ontario, Canada  
  Notes Downloaded from http://www2.ece.rochester.edu/projects/ufqp/PDF/2002/213NbNTimeOPTO_b.pdf This artcle was published in 2017 with only first author indicated (Zhang, J.). There were 8 more authors! Approved no  
  Call Number Serial 1750  
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Author Verevkin, A.; Zhang, J.; Pearlman, A.; Slysz, W.; Sobolewski, Roman; Korneev, A.; Kouminov, P.; Okunev, O.; Chulkova, G.; Gol'tsman, G. url  openurl
  Title Ultimate sensitivity of superconducting single-photon detectors in the visible to infrared range Type Miscellaneous
  Year 2004 Publication ResearchGate Abbreviated Journal ResearchGate  
  Volume Issue Pages  
  Keywords NbN SSPD, SNSPD  
  Abstract We present our quantum efficiency (QE) and noise equivalent power (NEP) measurements of the meandertype ultrathin NbN superconducting single-photon detector in the visible to infrared radiation range. The nanostructured devices with 3.5-nm film thickness demonstrate QE up to~ 10% at 1.3–1.55 µm wavelength, and up to 20% in the entire visible range. The detectors are sensitive to infrared radiation with the wavelengths down to~ 10 µm. NEP of about 2× 10-18 W/Hz1/2 was obtained at 1.3 µm wavelength. Such high sensitivity together with GHz-range counting speed, make NbN photon counters very promising for efficient, ultrafast quantum communications and another applications. We discuss the origin of dark counts in our devices and their ultimate sensitivity in terms of the resistive fluctuations in our superconducting nanostructured devices.  
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  Notes Not attributed to any publisher! File name: PR9VervekinSfin_f.doc; Author: JAOLEARY; Last modification date: 2004-02-26 Approved no  
  Call Number Serial 1751  
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