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Men’shchikov, E. M., Gogidze, I. G., Sergeev, A. V., Elant’ev, A. I., Kuminov, P. B., Gol’tsman, G. N., et al. (1997). Superconducting fast detector based on the nonequilibrium inductance response of a film of niobium nitride. Tech. Phys. Lett., 23(6), 486–488.
Abstract: A new type of fast detector is proposed, whose operation is based on the variation of the kinetic inductance of a superconducting film caused by nonequilibrium quasiparticles created by the electromagnetic radiation. The speed of the detector is determined by the rate of multiplication of photo-excited quasiparticles, and is nearly independent of the temperature, being less than 1 ps for NbN. Models based on the Owen-Scalapino scheme give a good description of the experimentally determined dependence of the power-voltage sensitivity of the detector on the modulation frequency. The lifetime of the quasiparticles is determined, and it is shown that the reabsorption of nonequilibrium phonons by the condensate has a substantial effect even in ultrathin NbN films 5 nm thick, and results in the maximum possible quantum yield. A low concentration of equilibrium quasiparticles and a high quantum yield result in a detectivity D*=1012 W−1·Hz1/2 at a temperature T=4.2 K and D*=1016 W−1·cm· Hz1/2 at T=1.6 K.
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Il'in, K. S., Karasik, B. S., Ptitsina, N. G., Sergeev, A. V., Gol'tsman, G. N., Gershenzon, E. M., et al. (1996). Electron-phonon-impurity interference in thin NbC films: electron inelastic scattering time and corrections to resistivity. In Czech. J. Phys. (Vol. 46, pp. 857–858).
Abstract: Complex study of transport properties of impure NbC films with the electron mean free pathl=0.6–13 nm show the crucial role of the electron-phonon-impurity interference (EPII). In the temperature range 20–70 K we found the interference correction to resistivity proportional to T2 and to the residual resistivity of the film. Using the comprehensive theory of EPII, we determine the electron coupling with transverse phonons and calculate the electron inelastic scattering time. Direct measurements of the inelastic electron scattering time using a response to a high-frequency amplitude modulated cw radiation agree well with the theory.
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Chulcova, G. M., Ptitsina, N. G., Gershenzon, E. M., Gershenzon, M. E., & Sergeev, A. V. (1996). Effect of the interference between electron-phonon and electron-impurity (boundary) scattering on resistivity Nb, Al, Be films. In Czech J. Phys. (Vol. 46, pp. 2489–2490).
Abstract: The temperature dependence of the resistivity of thin Nb, Al, Be films has been studied over a wide temperature range 4-300 K. We have found that the temperature-dependent correction to the residual resistivity is well described by the sum of the Bloch-Grüneisen term and the term originating from the interference between electron-phonon and electron-impurity scattering. Study of the transport interference phenomena allows to determine electron-phonon coupling in disordered metals. The interference term is proportional to T2 and also to the residual resistivity and dominates over the Bloch-Grüneisen term at low temperatures (T<40 K).
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Gousev, Y. P., Gol'tsman, G. N., Karasik, B. S., Gershenzon, E. M., Semenov, A. D., Barowski, H. S., et al. (1996). Quasioptical superconducting hot electron bolometer for submillmeter waves. Int. J. of Infrared and Millimeter Waves, 17(2), 317–331.
Abstract: We report on a superconducting hot electron bolometer coupled to radiation via a broadband antenna. The bolometer, a structured NbN film, was patterned on a thin dielectric membrane between terminals of a gold slotline antenna. We investigated the response to submillimeter radiation (wave-lengths ∼ 0.1 mm to 0.7 mm) in the fundamental Gaussian mode. We found that the directivity of the antenna was constant within a factor of 2.5 through the whole experimental range. The noise equivalent power of the bolometer at 119 µm was ∼ 3 · 10−13 W/Hz1/2; a time constant of ∼ 160 ps was estimated.
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Zorin, M., Lindgren, M., Danerud, M., Karasik, B., Winkler, D., Gol'tsman, G., et al. (1995). Nonequilibrium and bolometric responses of YBaCuO thin films to high-frequency modulated laser radiation. J. Supercond., 8(1), 11–15.
Abstract: Picosecond nonequilibrium and slow bolometric responses to infrared radiation from a patterned high-T c superconducting (HTS) film in resistive and normal states deposited onto LaAlO3, NdGaO3, and MgO substrates were investigated using both pulse and modulation techniques. The response time of 35 ps to a laser pulse of 17 ps FWHM has been observed. The intrinsic response time of the fast process is expected to be about a few picoseconds. The modulation technique, being free from the disadvantages of pulse methods (poor sensitivity, limited dynamic range), makes the detailed study of a number of relaxation processes possible. Besides the nonequilibrium response, two kinds of bolometric processes, namely phonon transport through the film-substrate interface and phonon thermal diffusion in a substrate, manifest themselves in certain frequency dependences.
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