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Sergeev A, Semenov A, Trifonov V, Karasik B, Gol'tsman G, Gershenzon E. Heat transfer in YBaCuO thin film/sapphire substrate system. J Supercond. 1994;7(2):341–4.
Abstract: The thermal boundary resistance at the YBaCuO thin film/Al2O3 substrate interface was investigated. The transparency for thermal phonons incident on the interface as well as for phonons moving from the substrate was determined. We have measured a transient voltage response of current-biased films to continuously modulated radiation. The observed knee in the modulation frequency dependence of the response reflects the crossover from the diffusion regime to the contact resistance regime of the heat transfer across the interface. The values of transparency were independently deduced both from the phonon escape time and from the time of phonon return to the film which were identified with peculiarities in the frequency dependence. The results are much more consistent with the acoustic mismatch theory than the diffuse mismatch model.
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Gershenzon E, Gershenzon ME, Gol'tsman GN, Semenov AD, Sergeev AV. Heating of quasiparticles in a superconducting film in the resistive state. JETP Lett. 1981;34(5):268–71.
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Gershenzon EM, Gershenzon ME, Gol'tsman GN, Semenov AD, Sergeev AV. Nonselective effect of electromagnetic radiation on a superconducting film in the resistive state. JETP Lett. 1982;36(7):296–9.
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Gershenzon EM, Gershenzon ME, Gol'tsman GN, Karasik BS, Semenov AD, Sergeev AV. Light-induced heating of electrons and the time of the inelastic electron-phonon scattering in the YBaCuO compound. JETP Lett. 1987;46(6):285–7.
Abstract: For the first time, measurements have been made on the electron energy relaxation time due to the electron--phonon interaction in films of the YBaCuO superconductor. The results indicate a significant intensification of the electron--phonon interaction in this compound as compared with normal superconducting metals.
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Aksaev EE, Gershenzon EM, Gol'tsman GN, Semenov AD, Sergeev AV. Interaction of electrons with thermal phonons in YBa2Cu3O7-δ films at low temperatures. JETP Lett. 1989;50(5):283–6.
Abstract: The time of electron-phonon interaction tau(eph) in YBaCuO films at low temperatures is studied. This is measured as the time of resistance relaxation in the resistive state of the superconducter, and is also determined from the increase in resistance under the action of radiation. Consistent results of these methods show that resistance relaxation in the resistive state is caused by cooling of the electron subsystem with respect to the phonon subsystem. The time tau(eph) is found to be inversely proportional to the temperature and comes to 80 ps when T = 1.6 K and 5 ps when T = 30 K. 6 refs.
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Semenov AD, Heusinger MA, Renk KF, Menschikov E, Sergeev AV, Elant'ev AI, et al. Influence of phonon trapping on the performance of NbN kinetic inductance detectors. IEEE Trans Appl Supercond. 1997;7(2):3083–6.
Abstract: Voltage and microwave photoresponse of NbN thin films to modulated and pulsed optical radiation reveals, far below the superconducting transition, a response time consistent with the lifetime of nonequilibrium quasiparticles. We show that even in 5 nm thick films at 4.2 K the phonon trapping is significant resulting in a quasiparticle lifetime of a few nanoseconds that is an order of magnitude larger than the recombination time. Values and temperature dependence of the quasiparticle lifetime obey the Bardeen-Cooper-Schrieffer theory and are in quantitative agreement with the electron-phonon relaxation rate determined from the resistive response near the superconducting transition. We discuss a positive effect of the phonon trapping on the performance of kinetic inductance detectors.
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Semenov AD, Goghidze IG, Gol’tsman GN, Sergeev AV, Gershenzon EM. Evidence for the spectral dependence of nonequilibrium picosecond photoresponse of YBaCuO thin films. Appl Phys Lett. 1993;63(5):681–3.
Abstract: The transient voltage photoresponse of current biased YBaCuO thin films to 20 ps laser pulses of 0.63 and 1.54 μm wavelengths is measured for temperatures around the superconducting transition region. The fast picosecond decay of the response is followed by a slow nanosecond relaxation which is associated with the bolometric effect. The magnitude of the fast component of the response varies in proportion to the square root of wavelength that plausibly reflects multiplication processes of photoexcited electrons via electron–electron scattering and interaction with high energy phonons.
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Semenov AD, Gol’tsman GN, Gogidze IG, Sergeev AV, Gershenzon EM, Lang PT, et al. Subnanosecond photoresponse of a YBaCuO thin film to infrared and visible radiation by quasiparticle induced suppression of superconductivity. Appl Phys Lett. 1992;60(7):903–5.
Abstract: We observed subnanosecond photoresponse of a structured superconducting YBa2Cu3O7−δ thin film to infrared and visible radiation. We measured the voltage response of a current biased film (thickness 700 Å) in a resistive state to radiation pulses. From our results we conclude a response time of about 90 ps and a responsivity of about 4×1010 Ω/J. We attribute the response to Cooper pair breaking and suppression of the superconducting energy gap induced by nonequilibrium quasiparticles.
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Gershenzon EM, Gol’tsman GN, Sergeev A, Semenov AD. Picosecond response of YBaCuO films to electromagnetic radiation. In: Gorzkowski W, Gutowski M, Reich A, Szymczak H, editors. Proc. European Conf. High-Tc Thin Films and Single Crystals.; 1990. p. 457–62.
Abstract: Radiation-induced change of the resistance was studied in the resistive state of YBaCuO films. Electron-phonon relaxation time T h was determmed from direct ep measurements and analysis of quasistationary electron heating. Temperature dependence of That TS 40 K was found to – ep be T h.. T'. The resul ts show that ep detectors with the response time of few picosecond at nitrogen temperature can be realized.
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Kitaygorsky J, Zhang J, Verevkin A, Sergeev A, Korneev A, Matvienko V, et al. Origin of dark counts in nanostructured NbN single-photon detectors. IEEE Trans Appl Supercond. 2005;15(2):545–8.
Abstract: We present our study of dark counts in ultrathin (3.5 to 10 nm thick), narrow (120 to 170 nm wide) NbN superconducting stripes of different lengths. In experiments, where the stripe was completely isolated from the outside world and kept at temperature below the critical temperature Tc, we detected subnanosecond electrical pulses associated with the spontaneous appearance of the temporal resistive state. The resistive state manifested itself as generation of phase-slip centers (PSCs) in our two-dimensional superconducting stripes. Our analysis shows that not far from Tc, PSCs have a thermally activated nature. At lowest temperatures, far below Tc, they are created by quantum fluctuations.
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