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Author Trifonov, V. A.; Karasik, B. S.; Zorin, M. A.; Gol'tsman, G. N.; Gershenzon, E. M.; Lindgren, M.; Danerud, M.; Winkler, D. url  openurl
  Title 9.6 μm wavelength mixing in a patterned YBa2Cu3O7-δ thin film Type Conference Article
  Year 1996 Publication Proc. 7th Int. Symp. Space Terahertz Technol. Abbreviated Journal (down) Proc. 7th Int. Symp. Space Terahertz Technol.  
  Volume Issue Pages 337-348  
  Keywords YBCO HTS HEB mixers  
  Abstract Hot-electron bolometric (HEB) mixing of 9.6 gm infrared radiation from two lasers in high-quality YBa2Cu307_3 (YBCO) patterned thin film has been demonstrated. A heterodyne measurement showed an intermediate frequency (IF) bandwidth of 18 GHz, limited by our measurement system. An intrinsic limit of 100 GHz is predicted. Between 0.1 and 1 GHz intermediate frequency, temperature fluctuations with an equivalent output noise temperature Tfl up to -150 K, contributed to the mixer noise while Johnson noise dominated above 1 GHz. The overall conversion loss at 77 K at low intermediate frequencies was measured to be -25 dB, of which 13 dB was due to the coupling loss. The IIEB mixer is very promising for use in heterodyne receivers within the whole infrared range.  
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  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1615  
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Author Gerecht, E.; Musante, C. F.; Wang, Z.; Yngvesson, K. S.; Mueller, E. R.; Waldman, J.; Gol'tsman, G. N.; Voronov, B. M.; Cherednichenco, S. I.; Svechnikov, S. I.; Yagoubov, P. A.; Gershenzon, E. M. url  openurl
  Title Optimization of hot eleciron bolometer mixing efficiency in NbN at 119 micrometer wavelength Type Conference Article
  Year 1996 Publication Proc. 7th Int. Symp. Space Terahertz Technol. Abbreviated Journal (down) Proc. 7th Int. Symp. Space Terahertz Technol.  
  Volume Issue Pages 584-600  
  Keywords NbN HEB mixers  
  Abstract We describe an investigation of a NbN HEB mixer for 2.5 THz. An intrinsic conversion loss of 23 dB has been measured with a two-laser measurement technique. The conversion loss was limited by the LO power available and is expected to decrease to 10 dB or less when sufficient LO power is available. For this initial experiment we used a prototype device which is directly coupled to the laser beams. We present results for a back-short technique that improves the optical coupling to the device and describe our progress for an antenna-coupled device with a smaller dimension. Based on our measured data for conversion loss and device output noise level, we predict that NbN HEB mixers will be capable of achieving DSB receiver noise temperatures of ten times the quantum noise limit in the THz range.  
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  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1616  
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Author Ekström, H.; Kroug, M.; Belitsky, V.; Kollberg, E.; Olsson, H.; Goltsman, G.; Gershenzon, E.; Yagoubov, P.; Voronov, B.; Yngvesson, S. url  openurl
  Title Hot electron mixers for THz applications Type Conference Article
  Year 1996 Publication Proc. 30th ESLAB Abbreviated Journal (down) Proc. 30th ESLAB  
  Volume Issue Pages 207-210  
  Keywords NbN HEB mixers  
  Abstract We have measured the noise performance of 35 A thin NbN HEB devices integrated with spiral antennas on antireflection coated silicon substrate lenses at 620 GHz. From the noise measurements we have determined a total conversion gain of the receiver of—16 dB, and an intrinsic conversion of about-10 dB. The IF bandwidth of the 35 A thick NbN devices is at least 3 GHz. The DSB receiver noise temperature is less than 1450 K. Without mismatch losses, which is possible to obtain with a shorter device, and with reduced loss from the beamsplitter, we expect to achieve a DSB receiver noise temperature of less ‘than 700 K.  
  Address Noordwijk, Netherlands  
  Corporate Author Thesis  
  Publisher Place of Publication Editor Rolfe, E. J.; Pilbratt, G.  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
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  ISSN ISBN Medium  
  Area Expedition Conference Submillimetre and Far-Infrared Space Instrumentation  
  Notes Approved no  
  Call Number Serial 1606  
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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 (down) 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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  ISSN 0163-1829 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:9982274 Approved no  
  Call Number Serial 1612  
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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 (down) 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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  Series Editor Series Title Abbreviated Series Title  
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  ISSN 0021-3640 ISBN Medium  
  Area Expedition 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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