|   | 
Details
   web
Records
Author Il'in, K. S.; Gol'tsman, G. N.; Voronov, B. M.; Sobolewski, Roman
Title (up) Characterization of the electron energy relaxation process in NbN hot-electron devices 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 390-397
Keywords HEB mixers, SSPD, SNSPD, NbN films, Nb films
Abstract We report on transient measurements of electron energy relaxation in NbN films with 300-fs time resolution. Using an electro-optic sampling technique, we have studied the photoresponse of 3.5-nm-thick NbN films deposited on sapphire substrates and exposed to 100-fs-wide optical pulses. Our experimental data analysis was based on the two-temperature model and has shown that in our films at the superconducting transition 10.5 K the inelastic electron-phonon scattering time was about (111}+-__.2) ps. This response time indicated that the maximum intermediate-frequency band of a NbN hot-electron phonon-cooled mixer should reach (16+41-3) GHz if one eliminates the bolometric phonon-heating effect. We have suggested several ways to increase the effectiveness of phonon cooling to achieve the above intrinsic value of the NbN mixer bandwidth.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1576
Permanent link to this record
 

 
Author Verevkin, A.; Zhang, J.; Sobolewski, Roman; Lipatov, A.; Okunev, O.; Chulkova, G.; Korneev, A.; Smirnov, K.; Gol'tsman, G. N.; Semenov, A.
Title (up) 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.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 331
Permanent link to this record
 

 
Author Semenov, Alexei D; Gol'tsman, Gregory N; Sobolewski, Roman
Title (up) Hot-electron effect in superconductors and its applications for radiation sensors Type Journal Article
Year 2002 Publication Superconductor Science and Technology Abbreviated Journal Supercond. Sci. Technol.
Volume 15 Issue 4 Pages R1-R16
Keywords HEB, SSPD
Abstract The paper reviews the main aspects of nonequilibrium hot-electron phenomena in superconductors and various theoretical models developed to describe the hot-electron effect. We discuss implementation of the hot-electron avalanche mechanism in superconducting radiation sensors and present the most successful practical devices, such as terahertz mixers and direct intensity detectors, for far-infrared radiation. Our presentation also includes the novel approach to hot-electron quantum detection implemented in superconducting x-ray to optical photon counters.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
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 416
Permanent link to this record
 

 
Author Kitaygorsky, Jennifer; Komissarov, I.; Jukna, A.; Sobolewski, Roman; Minaeva, O.; Kaurova, N.; Korneev, A.; Voronov, B.; Milostnaya, I.; Gol'Tsman, Gregory
Title (up) Nanosecond, transient resistive state in two-dimensional superconducting stripes Type Abstract
Year 2006 Publication Proc. APS March Meeting Abbreviated Journal Proc. APS March Meeting
Volume Issue Pages H38.13
Keywords NbN stripes
Abstract We have observed, nanosecond-in-duration, transient voltage pulses, generated across two-dimensional (2-D) NbN stripes (width: 100--500 nm; thickness: 3.5--10 nm) of various lengths (1--500 μm), when the wires were completely isolated from the outside world, biased at currents close to the critical current, and kept at temperatures below the mean-field critical temperature Tco. In 2-D superconducting films, at temperatures below the Kosterlitz-Thouless transition, all vortices are bound and the resistance is zero. However, these vortices can get unbound when a large enough transport current is applied. The latter results in a transient resistive state, which manifests itself as spontaneous, 2.5--8-ns-long voltage pulses with the amplitude corresponding to the unbinding potential of a vortex pair. In our 100-nm-wide stripes, we have also observed the formation of phase slip centers (PSCs) at temperatures close to Tco, and a mixture of PSCs and unbound vortex-antivortex pairs at low temperatures.
Address Baltimore, MD
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1454
Permanent link to this record
 

 
Author Il'in, K. S.; Lindgren, M.; Currie, M. A.; Semenov, D.; Gol'tsman, G. N.; Sobolewski, Roman; Cherednichenko, S. I.; Gershenzon, E. M.
Title (up) Picosecond hot-electron energy relaxation in NbN superconducting photodetectors Type Journal Article
Year 2000 Publication Appl. Phys. Lett. Abbreviated Journal Appl. Phys. Lett.
Volume 76 Issue 19 Pages 2752-2754
Keywords NbN HEB detectors, two-temperature model, IF bandwidth
Abstract We report time-resolved characterization of superconducting NbN hot-electron photodetectors using an electro-optic sampling method. Our samples were patterned into micron-size microbridges from 3.5-nm-thick NbN films deposited on sapphire substrates. The devices were illuminated with 100 fs optical pulses, and the photoresponse was measured in the ambient temperature range between 2.15 and 10.6 K (superconducting temperature transition TC). The experimental data agreed very well with the nonequilibrium hot-electron, two-temperature model. The quasiparticle thermalization time was ambient temperature independent and was measured to be 6.5 ps. The inelastic electron–phonon scattering time Ï„e–ph tended to decrease with the temperature increase, although its change remained within the experimental error, while the phonon escape time Ï„es decreased almost by a factor of two when the sample was put in direct contact with superfluid helium. Specifically, Ï„e–ph and Ï„es, fitted by the two-temperature model, were equal to 11.6 and 21 ps at 2.15 K, and 10(±2) and 38 ps at 10.5 K, respectively. The obtained value of Ï„e–ph shows that the maximum intermediate frequency bandwidth of NbN hot-electron phonon-cooled mixers operating at TC can reach 16(+4/–3) GHz if one eliminates the bolometric phonon-heating effect.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0003-6951 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 856
Permanent link to this record