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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.
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Call Number Serial 1576
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Author Gurovich, B. A.; Tarkhov, M. A.; Prikhod'ko, K. E.; Kuleshova, E. A.; Komarov, D. A.; Stolyarov, V. L.; Olshanskii, E. D.; Goncharov, B. V.; Goncharova, D. A.; Kutuzov, L. V.; Domantovskii, A. G.
Title (up) Controlled modification of superconducting properties of NbN ultrathin films under composite ion beam irradiation Type Journal Article
Year 2014 Publication Nanotechnologies in Russia Abbreviated Journal Nanotechnologies in Russia
Volume 9 Issue 7 Pages 386-390
Keywords superconducting NbN films composite ion beam irradiation protoning
Abstract In this work, the results of studying the microstructure and superconducting properties of ultrathin films on the basis of NbN in the initial state and after modification by being subjecting to composite ion beam irradiation with the energy ~1–3) keV are presented. HRTEM analysis showed that the initial films on the sapphire substrate in orientation “c-cut” are characterized by a grain size essentially exceeding the film thickness, while on the other substrates the size of grains corresponds to the thickness of film. Using XPS analysis, it was shown that in the initial films the atomic ratio of Nb and N is 0.51/0.49, respectively, the percentage of oxygen being lower than 5%. For ultrathin films 5 nm in thickness, the critical temperature of transit to superconducting state (T c) is found to be ~3.6 K and the density of critical current is jc ~8MA/cm2. In the work it is experimentally determined that the irradiation of NbN films by composite ion beams leads to the controlled modification of its superconducting properties due to the process of selective substitution of nitrogen atoms on the oxygen atoms.
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Call Number Serial 1000
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Author Manova, N. N.; Simonov, N. O.; Korneeva, Y. P.; Korneev, A. A.
Title (up) Developing of NbN films for superconducting microstrip single-photon detector Type Conference Article
Year 2020 Publication J. Phys.: Conf. Ser. Abbreviated Journal J. Phys.: Conf. Ser.
Volume 1695 Issue Pages 012116 (1 to 5)
Keywords NbN SSPD, SNSPD, NbN films
Abstract We optimized NbN films on a Si substrate with a buffer SiO2 layer to produce superconducting microstrip single-photon detectors with saturated dependence of quantum efficiency (QE) versus normalized bias current. We varied thickness of films and observed the maximum QE saturation for device based on the thinner film with the lowest ratio RS300/RS20.
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Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1742-6588 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1786
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Author Gousev, Y. P.; Semenov, A. D.; Gol'tsman, G. N.; Sergeev, A. V.; Gershenzon, E. M.
Title (up) Electron-phonon interaction in disordered NbN films Type Journal Article
Year 1994 Publication Phys. B Condens. Mat. Abbreviated Journal Phys. B Condens. Mat.
Volume 194-196 Issue Pages 1355-1356
Keywords NbN films
Abstract Electron-phonon interaction time has been investigated in disordered films of NbN. A temperatures below 5.5 K tau_eph ~ T -1"6 which is attributed to the renormalisation of phonon spectrum in thin films.
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ISSN 0921-4526 ISBN Medium
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Notes Approved no
Call Number Serial 1649
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Author Titova, N. A.; Baeva, E. M.; Kardakova, A. I.; Goltsman, G. N.
Title (up) Fabrication of NbN/SiNx:H/SiO2 membrane structures for study of heat conduction at low temperatures Type Conference Article
Year 2020 Publication J. Phys.: Conf. Ser. Abbreviated Journal J. Phys.: Conf. Ser.
Volume 1695 Issue Pages 012190
Keywords NbN films, insulating membrane
Abstract Here we report on the development of NbN/SiNx:H/SiO2-membrane structures for investigation of the thermal transport at low temperatures. Thin NbN films are known to be in the regime of a strong electron-phonon coupling, and one can assume that the phononic and electronic baths in the NbN are in local equilibrium. In such case, the cooling of the NbN-based devices strongly depends on acoustic matching to the substrate and substrate thermal characteristics. For the insulating membrane much thicker than the NbN film, our preliminary results demonstrate that the membrane serves as an additional channel for the thermal relaxation of the NbN sample. That implies a negligible role of thermal boundary resistance of the NbN-SiNx:H interface in comparison with the internal thermal resistance of the insulating membrane.
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ISSN 1742-6588 ISBN Medium
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Notes Approved no
Call Number Serial 1165
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