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Author Jukna, A.; Kitaygorsky, J.; Pan, D.; Cross, A.; Perlman, A.; Komissarov, I.; Sobolewski, R.; Okunev, O.; Smirnov, K.; Korneev, A.; Chulkova, G.; Milostnaya, I.; Voronov, B.; Gol'tsman, G. doi  openurl
  Title (down) Dynamics of hotspot formation in nanostructured superconducting stripes excited with single photons Type Journal Article
  Year 2008 Publication Acta Physica Polonica A Abbreviated Journal Acta Physica Polonica A  
  Volume 113 Issue 3 Pages 955-958  
  Keywords SSPD, SNSPD  
  Abstract Dynamics of a resistive hotspot formation by near-infrared-wavelength single photons in nanowire-type superconducting NbN stripes was investigated. Numerical simulations of ultrafast thermalization of photon-excited nonequilibrium quasiparticles, their multiplication and out-diffusion from a site of the photon absorption demonstrate that 1.55 μm wavelength photons create in an ultrathin, two-dimensional superconducting film a resistive hotspot with the diameter which depends on the photon energy, and the nanowire temperature and biasing conditions. Our hotspot model indicates that under the subcritical current bias of the 2D stripe, the electric field penetrates the superconductor at the hotspot boundary, leading to suppression of the stripe superconducting properties and accelerated development of a voltage transient across the stripe.  
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  Notes Approved no  
  Call Number Serial 1414  
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Author Baselmans, J. J. A.; Hajenius, M.; Gao, J. R.; Klapwijk, T. M.; de Korte, P. A. J.; Voronov, B.; Gol'tsman, G. doi  openurl
  Title (down) Doubling of sensitivity and bandwidth in phonon cooled hot electron bolometer mixers Type Journal Article
  Year 2004 Publication Appl. Phys. Lett. Abbreviated Journal Appl. Phys. Lett.  
  Volume 84 Issue 11 Pages 1958-1960  
  Keywords NbN HEB mixers  
  Abstract We demonstrate that the performance of NbN lattice cooled hot electron bolometer mixers depends strongly on the interface quality between the bolometer and the contact structure. We show experimentally that both the receiver noise temperature and the gain bandwidth can be improved by more than a factor of 2 by cleaning the interface and adding an additional superconducting interlayer to the contact pad. Using this we obtain a double sideband receiver noise temperature TN,DSB=950 K

at 2.5 THz and 4.3 K, uncorrected for losses in the optics. At the same bias point, we obtain an IF gain bandwidth of 6 GHz.
 
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  Notes Approved no  
  Call Number Serial 352  
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Author Verevkin, A.; Gershenzon, E. M.; Gol'tsman, G. N.; Ptitsina, N. G.; Chulkova, G. M.; Smirnov, K. S.; Sobolewski, R. url  openurl
  Title (down) Direct measurements of energy relaxation times in two-dimensional structures under quasi-equilibrium conditions Type Conference Article
  Year 2002 Publication Mater. Sci. Forum Abbreviated Journal Mater. Sci. Forum  
  Volume 384-3 Issue Pages 107-116  
  Keywords 2DEG, AlGaAs/GaAs  
  Abstract A new microwave technique was successfully applied for direct studies of energy relaxation times in two-dimensional AlGaAs/GaAs structures under quasi-equilibrium conditions in the nanosecond and picosecond time scale. We report our results of energy relaxation time measurements in the temperature range 1.6-50 K, in quantum Hall effect regime in magnetic fields up to 4 T.  
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  ISSN ISBN Medium  
  Area Expedition Conference Materials Science Forum  
  Notes Approved no  
  Call Number Serial 1536  
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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 (down) 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 Conference  
  Notes Approved no  
  Call Number Serial 1609  
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Author Lobanov, Y.V.; Tong, C.-Y.E.; Hedden, A.S.; Blundell, R.; Voronov, B.M.; Gol'tsman, G.N. doi  openurl
  Title (down) Direct measurement of the gain and noise bandwidths of HEB mixers Type Journal Article
  Year 2011 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal IEEE Trans. Appl. Supercond.  
  Volume 21 Issue 3 Pages 645-648  
  Keywords waveguide NbN HEB mixers  
  Abstract The intermediate frequency (IF) bandwidth of a hot electron bolometer (HEB) mixer is an important parameter of the mixer, in that it helps to determine its suitability for a given application. With the availability of wideband low noise amplifiers, it is simple to measure the performance of an HEB mixer over a wide range of IF at a fixed LO frequency using the standard Y-factor method. This in-situ method allows us to measure both the gain and noise bandwidths simultaneously. We have also measured mixer output impedance with a vector network analyser. Intrinsic time constant has been extracted from the impedance data and compared to the mixer's bandwidths determined from receiver Y-factor measurement.  
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  Area Expedition Conference  
  Notes Approved no  
  Call Number RPLAB @ gujma @ Serial 720  
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