|
|
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.
|
|
|
|
Gershenzon, E. M., Gol'tsman, G. N., Ptitsina, N. G., & Riger, E. R. (1986). Effect of electron-electron collisions on the trapping of free carriers by shallow impurity centers in germanium. Sov. Phys. JETP, 64(4), 889–897.
Abstract: Cascade Auger recombination of free carriers on shallow impurities in Ge is investigated under quasi-equilibrium conditions (T= 2-12 K) and in impurity breakdown. The Auger capture cross sections are found to be a,= 5. 10-l9 T-'n cm2 for donors and uip= 7- T-5p cm2 for acceptors. It is shown that in an isotropic semiconductor (p-Ge) ui is well described by the cascade-capture theory that takes into account only electron-electron collisions. In an anisotropic semiconductor ui is considerably larger (n-Ge, strongly uniaxially compressedp-Ge). Under impurity breakdown conditions the electron-electron collisions determine the lifetimes of the free carriers only in samples with appreciable density of the compensating impurity (Nk loi3 cmP3).
|
|
|
|
Semenov, A. D., Gol’tsman, G. N., Gogidze, I. G., Sergeev, A. V., Gershenzon, E. M., Lang, P. T., et al. (1992). Subnanosecond photoresponse of a YBaCuO thin film to infrared and visible radiation by quasiparticle induced suppression of superconductivity. Appl. Phys. Lett., 60(7), 903–905.
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.
|
|
|
|
Kawamura, J., Tong, C. - Y. E., Blundell, R., Papa, D. C., Hunter, T. R., Patt, F., et al. (2001). Terahertz-frequency waveguide NbN hot-electron bolometer mixer. IEEE Trans. Appl. Supercond., 11(1), 952–954.
Abstract: We have developed a low-noise waveguide heterodyne receiver for operation near 1 THz using phonon-cooled NbN hot-electron bolometers. The mixer elements are submicron-sized microbridges of 4 nm-thick NbN film fabricated on a quartz substrate. Operating at a bath temperature of 4.2 K, the double-sideband receiver noise temperature is 760 K at 1.02 THz and 1100 K at 1.26 THz. The local oscillator is provided by solid-state sources, and power measured at the source is less than 1 /spl mu/W. The intermediate frequency bandwidth exceeds 2 GHz. The receiver was used to make the first ground-based heterodyne detection of a celestial spectroscopic line above 1 THz.
|
|
|
|
Voronov, B. M., Gershenzon, E. M., Gol'tsman, G. N., Gogidze, I. G., Gusev, Y. P., Zorin, M. A., et al. (1992). Picosecond range detector base on superconducting niobium nitride film sensitive to radiation in spectral range from millimeter waves up to visible light. Sverkhprovodimost': Fizika, Khimiya, Tekhnika, 5(5), 955–960.
Abstract: Fast-operating picosecond detector of electromagnetical radiation is developed on the basis of fine superconducting film of niobium nitride with high sensitivity within spectral range from millimetric waves up to visible light. Detector sensitive element represents structure covering narrow parallel strips with micron sizes included in the rupture of microstrip line. Detecting ability of the detector and time constant measured using amplitude-simulated radiation of reverse wave tubes and pulse radiation of picosecond gas and solid-body lasers, constitute D*≅1010 W-1·cm·Hz-1/2 and τ≤5 ps respectively, at 10 K temperature. The expected value of time constant of the detector at 10 K obtained via extrapolation of directly measured dependence that is, τ ∝ τ-1, constitutes 20 ps. Experimental data demonstrate that detection mechanism is linked with electron heating effect.
|
|
|
|
Ptitsina, N. G., Chulkova, G. M., & Gershenzon, E. M. (1995). Influence of the interference of electron-phonon and electron-impurity scattering on the conductivity of unordered Nb films. JETP, 80(5), 960–964.
Abstract: The temperature dependence of the resistivity of Nb thin films has been studied at T=4.2-300 K. It has been shown that quantum interference between electron-phonon and electron-impurity scattering determines the temperature dependence of the resistivity of the films investigated over a broad temperature range. The magnitude of the contribution of the electron-phonon-impurity,interference is described satisfactorily by the theory developed by Reizer and Sergeev {Zh. Eksp. Teor. Fiz. 92,2291 (1987) [Sov. Phys. JETP 65, 1291 (1987)l). The interaction constants of electrons with longitudinal and transverse phonons in Nb films have been determined for the first time by comparing the experimental data with the theory. The values of the constants obtained are consistent with the data on the inelastic electron-phonon scattering times in the films investigated. The contribution of the transverse phonons is dominant both in the interference correction to the resistivity and in the electron energy relaxation.
|
|
|
|
Cherednichenko, S., Yagoubov, P., Il'in, K., Gol'tsman, G., & Gershenzon, E. (1997). Large bandwidth of NbN phonon-cooled hot-electron bolometer mixers. In Proc. 27th Eur. Microwave Conf. (Vol. 2, pp. 972–977). IEEE.
Abstract: The bandwidth of NbN phonon-cooled hot electron bolometer mixers has been systematically investigated with respect to the film thickness and film quality variation. The films, 2.5 to 10 nm thick, were fabricated on sapphire substrates using DC reactive magnetron sputtering. All devices consisted of several parallel strips, each 1 um wide and 2 um long, placed between Ti-Au contact pads. To measure the gain bandwidth we used two identical BWOs operating in the 120-140 GHz frequency range, one functioning as a local oscillator and the other as a signal source. The majority of the measurements were made at an ambient temperature of 4.2 K with optimal LO and DC bias. The maximum 3 dB bandwidth (about 4 GHz) was achieved for the devices made of films which were 2.5-3.5 nm thick, had a high critical temperature, and high critical current density. A theoretical analysis of bandwidth for these mixers based on the two-temperature model gives a good description of the experimental results if one assumes that the electron temperature is equal to the critical temperature.
|
|
|
|
Voronov, B. M., Gershenzon, E. M., Gol'tsman, G. N., Gubkina, T. O., & Semash, V. D. (1994). Superconductive properties of ultrathin NbN films on different substrates. Sverkhprovodimost': Fizika, Khimiya, Tekhnika, 7(6), 1097–1102.
Abstract: A study was made on dependence of surface resistance, critical temperature and width of superconducting transition on application temperature and thickness of NbN films, which varied within the range of 3-10 nm. Plates of sapphire, fused and monocrystalline quartz, MgO, as well as Si and silicon oxide were used as substrates. NbN films with 160 μθ·cm specific resistance and 16.5 K (Tc) critical temperature were obtained on sapphire substrates. Intensive growth of ΔTc was noted for films, applied on fused quartz, with increase of precipitation temperature. This is explained by occurrence of high tensile stresses in NbN films, caused by sufficient difference of thermal coefficients of expansion of NbN and quartz.
|
|
|
|
Gershenzon, E. M., Gol'tsman, G. N., Karasik, B. S., Lugovaya, G. Y., Serebryakova, N. A., & Chinkova, E. V. (1992). Infrared radiation detectors on the base of electron heating in resistive state films from traditional superconducing materials. Sverkhprovodimost': Fizika, Khimiya, Tekhnika, 5(6), 1129–1140.
Abstract: Characteristics of infrared radiation detectors based on electron heating in thin superconducting films transformed at T ≤ Tc to a resistive state by transport current and, if necessary, by magnetic field are investigated. A comparison is made of the characteristics of the detectors fabricated of different materials: aluminium, niobium, Mo0.5Re0.5. Some devices with different topology of the reception area are considered. Electron heating detectors are comparable by their sensitivity with superconducting bolometers, but differ in a high fast-response.
|
|
|
|
Gershenzon, E., Goltsman, G., Elantev, A., & Kagane, M. (1978). Energy-spectrum of small donors and acceptors in germanium and effect of magnetic-field on it. In Izv. Akad. Nauk SSSR, Seriya Fizicheskaya (Vol. 42, pp. 1142–1148).
|
|
