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Finkel, M. I., Maslennikov, S. N., & Gol'tsman, G. N. (2005). Terahertz heterodyne receivers based on superconductive hot-electron bolometer mixers. Radiophys. Quant. Electron., 48(10-11), 859–864.
Abstract: We consider recent results in development of hot-electron bolometer mixers. Special attention is paid to optimization of the contacts between the antenna and the active area of a superconducting film. An important result in the study of the parasitic effect of direct detection is obtained during the measurement of the noise temperatures by the hot/cold load method. The latest results of studies of the waveguide hot-electron bolometer mixers and their successful practical applications are considered. Progress in development of high-frequency (over 1.3 THz) heterodyne receivers for several important international projects is discussed and new submillimeter radio astronomy projects ESPRIT and SAFIR are described.
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Gershenzon, E. M., Gol'tsman, G. N., & Ptitsina, N. G. (1979). Population and lifetime of excited states of shallow impurities in Ge. Sov. Phys. JETP, 49(2), 355–362.
Abstract: An investigation was made of the dependences of the intensities of photothermal ionization lines of excited states of shallow impurities in Ge on the intensity of impurity-absorbed background radiation and on temperature. The results obtained were used to find the density and lifetime of carriers of lower excited states of the impurity centers. The lifetimes of the excited states of donors in Ge were 10-~-10-" sec and the lifetime of the lower excited state of acceptors was -lo-' sec. In the presence of background radiation the population of the excited states was very different from the equilibrium value and, in particular, a population inversion of the 2pk, state relative to the 3p0 and 3s states was observed.
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Finkel, M. I., Maslennikov, S. N., & Gol'tsman, G. N. (2007). The concept of the receiving complex for the “Millimetron” space radio telescope. Radiophys. Quant. Electron., 50(10-11), 837–846.
Abstract: We consider the current status of research in the development of a submillimeter and far-infrared receiving instrument and propose promising solutions for the receivers of the spaceborne telescope “Millimetron,” which allow one to realize comprehensively the opportunities given by this international project administrated by the Astrospace Center of the P. N. Lebedev Physical Institute of the Russian Academy of Sciences.
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Gershenzon, E. M., Gershenzon, M. E., Gol'tsman, G. N., Semyonov, A. D., & Sergeev, A. V. (1984). Heating of electrons in superconductor in the resistive state due to electromagnetic radiation. Solid State Communications, 50(3), 207–212.
Abstract: The effect of heating electrons with respect to phonons in a thin superconducting film driven into the resistive state by the current and the external magnetic field has been observed and investigated. This effect caused by the electromagnetic radiation is manifested in the increased resistance of the film and is not selective over the frequency range from 1010 to 1015 Hz. That the effect is frequency independent under the conditions of strong electron scattering caused by static defects is explained by the decisive role of electron -electron collisions in forming the distribution function. The characteristic time of resistance change, obtained experimentally, corresponds to the relaxation time of the order parameter near the superconducting transition and to the relaxation time of the nonelastic electron-phonon interaction at lower temperatures and in lower magnetic fields.
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Aksaev, E. E., Gershenzon, E. M., Gol'tsman, G. N., Semenov, A. D., & Sergeev, A. V. (1989). Interaction of electrons with thermal phonons in YBa2Cu3O7-δ films at low temperatures. JETP Lett., 50(5), 283–286.
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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Gershenzon, E. M., Gol'tsman, G. N., Multanovskii, V. V., & Ptitsyna, N. G. (1979). Capture of photoexcited carriers by shallow impurity centers in germanium. Sov. Phys. JETP, 50(4), 728–734.
Abstract: Measurements were made of the lifetimes rf of free carriers and the relaxation time 7, of the submillimeter impurity photoconductivity when carriers are captured by attracting shallow donors and acceptom in Ge. It is nod that in samples with capture-center concentration N,Z 10"cm-' the relaxation time 7, greatly exceeds rf in the temperature range 4.2-12 K. The measured values of 7,- are compared with the calculation of cascade recombination by the classical model. To evaluate the data on T,, the distinguishing features of this model are considered for the nonstationary case. The substantial difference betweea the values of rf and T, is attributed to re-emission of the carriers from the excited states of the shallow impurities.
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Verevkin, A., Pearlman, A., Slysz, W., Zhang, J., Currie, M., Korneev, A., et al. (2004). Ultrafast superconducting single-photon detectors for near-infrared-wavelength quantum communications. J. Modern Opt., 51(9-10), 1447–1458.
Abstract: The paper reports progress on the design and development of niobium-nitride, superconducting single-photon detectors (SSPDs) for ultrafast counting of near-infrared photons for secure quantum communications. The SSPDs operate in the quantum detection mode, based on photon-induced hotspot formation and subsequent appearance of a transient resistive barrier across an ultrathin and submicron-width superconducting stripe. The devices are fabricated from 3.5 nm thick NbN films and kept at cryogenic (liquid helium) temperatures inside a cryostat. The detector experimental quantum efficiency in the photon-counting mode reaches above 20% in the visible radiation range and up to 10% at the 1.3–1.55 μn infrared range. The dark counts are below 0.01 per second. The measured real-time counting rate is above 2 GHz and is limited by readout electronics (the intrinsic response time is below 30 ps). The SSPD jitter is below 18 ps, and the best-measured value of the noise-equivalent power (NEP) is 2 × 10−18 W/Hz1/2. at 1.3 μm. In terms of photon-counting efficiency and speed, these NbN SSPDs significantly outperform semiconductor avalanche photodiodes and photomultipliers.
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Ryabchun, S. A., Tretyakov, I. V., Pentin, I. V., Kaurova, N. S., Seleznev, V. A., Voronov, B. M., et al. (2009). Low-noise wide-band hot-electron bolometer mixer based on an NbN film. Radiophys. Quant. Electron., 52(8), 576–582.
Abstract: We develop and study a hot-electron bolometer mixer made of a two-layer NbN–Au film in situ deposited on a silicon substrate. The double-sideband noise temperature of the mixer is 750 K at a frequency of 2.5 THz. The conversion efficiency measurements show that at the superconducting transition temperature, the intermediate-frequency bandwidth amounts to about 6.5 GHz for a mixer 0.112 μm long. These record-breaking characteristics are attributed to the improved contacts between a sensitive element and a helical antenna and are reached due to using the in situ deposition of NbN and Au layers at certain stages of the process.
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Gershenzon, E. M., & Gol'tsman, G. N. (1988). Effect of electromagnetic radiation on a superconductor in a magnetic field. In Izv. Akad. Nauk SSSR, Seriya Fizicheskaya (Vol. 52, pp. 449–451).
Abstract: The effect of electromagnetic radiation on thin superconducting films of Nb with a large number of static defects is investigated experimentally for the case where the film is in the resistive state due to an applied magnetic field and transport current. The results obtained are found to be well described by a model of spatially homogeneous electron heating. It is noted that the results obtained here for Nb films are also valid for Al, NbN, and MoRe films.
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Verevkin, A. A., Ptitsina, N. G., Chulcova, G. M., Gol'Tsman, G. N., Gershenzon, E. M., & Yngvesson, K. S. (1996). Determination of the limiting mobility of a two-dimensional electron gas in AlxGa1-xAs/GaAs heterostructures and direct measurement of the energy relaxation time. Phys. Rev. B Condens. Matter., 53(12), R7592–R7595.
Abstract: We present results for a method to measure directly the energy relaxation time (τe) for electrons in a single AlxGa1−xAs/GaAs heterojunction; measurements were performed from 1.6 to 15 K under quasiequilibrium conditions. We find τeαT−1 below 4 K, and τe independent of T above 4 K. We have also measured the energy-loss rate, ⟨Q⟩, by the Shubnikov-de Haas technique, and find ⟨Q⟩α(T3e−T3) for T<~4.2 K; Te is the electron temperature. The values and temperature dependence of τe and ⟨Q⟩ for T<4 K agree with calculations based on piezoelectric and deformation potential acoustic phonon scattering. At 4.2 K, we can also estimate the momentum relaxation time, τm, from our measured τe. This leads to a preliminary estimate of the phonon-limited mobility at 4.2 K of μ=3×107 cm2/Vs (ns=4.2×1011 cm−2), which agrees well with published numerical calculations, as well as with an earlier indirect estimate based on measurements on a sample with much higher mobility.
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Lang, P. T., Leipold, I., Knott, W. J., Semenov, A. D., Gol'tsman, G. N., & Renk, K. F. (1991). New far-infrared laser lines from CH3Cl and CH3Br optically pumped with a continuously tunable high pressure CO2 laser. Appl. Phys. B, 53(4), 207–212.
Abstract: In this paper we report on the detection of new far-infrared laser lines from CH3Cl and CH3Br optically pumped with a continuously tunable high pressure CO2 laser. We found 80 new lines for CH3Cl and 9 new lines for CH3Br in the frequency region between 16 cm−1 and 41 cm−1, all due to stimulated Raman scattering. For the Raman gain regions bandwidths up to about 700 MHz were found. We also observed high intensity short far-infrared laser pulses of durations in the nanosecond regime.
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Smirnov, A. V., Baryshev, A. M., de Bernardis, P., Vdovin, V. F., Gol'tsman, G. N., Kardashev, N. S., et al. (2012). The current stage of development of the receiving complex of the millimetron space observatory. Radiophys. Quant. Electron., 54(8), 557–568.
Abstract: We present an overview of the state of the onboard receiving complex of the Millimetron space observatory in the development phase of its preliminary design. The basic parameters of the onboard equipment planned to create and required for astrophysical observations are considered. A review of coherent and incoherent detectors, which are central to each receiver of the observatory, is given. Their characteristics and limiting parameters feasible at the present level of technology are reported.
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Jiang, L., Miao, W., Zhang, W., Li, N., Lin, Z. H., Yao, Q. J., et al. (2006). Characterization of a quasi-optical NbN superconducting HEB mixer. IEEE Trans. Microwave Theory Techn., 54(7), 2944–2948.
Abstract: In this paper, the performance of a quasi-optical NbN superconducting hot-electron bolometer (HEB) mixer, cryogenically cooled by a close-cycled 4-K refrigerator, is thoroughly investigated at 300, 500, and 850 GHz. The lowest receiver noise temperatures measured at the respective three frequencies are 1400, 900, and 1350 K, which can go down to 659, 413, and 529 K, respectively, after correcting the loss and associated noise contribution of the quasi-optical system before the measured superconducting HEB mixer. The stability of the quasi-optical superconducting HEB mixer is also investigated here. The Allan variance time measured with a local oscillator pumping at 500 GHz and an IF bandwidth of 110 MHz is 1.5 s at the dc-bias voltage exhibiting the lowest noise temperature and increases to 2.5 s at a dc bias twice that voltage.
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Gershenzon, E. M., Gol'tsman, G. N., Multanovskii, V. V., & Ptitsina, N. G. (1983). Kinetics of electron and hole binding into excitons in germanium. Sov. Phys. JETP, 57(2), 369–376.
Abstract: The kinetics of binding of free carriers'into excitons under stationary and nonstationary conditions is studied by investigating the submillimeter photoconductivity of Ge in a wide range of temperatures and of excitation levels. It is shown that the absolute values and the temperature dependence of the binding cross section (o- T-'.' ) can be satisfactorily described by the cascade recombination theory. The value of o and its temperature dependence differ significantly from the cross sections, measured in the same manner, for capture by attracting small impurities. Under nonstationary conditions, just as in the case of recombination with shallow impurities, a signifi- cant role is played by the sticking of the carriers in highly excited states.
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Gershenzon, E. M., Gershenzon, M. E., Gol'tsman, G. N., Semenov, A. D., & Sergeev, A. V. (1984). Heating of electrons in a superconductor in the resistive state by electromagnetic radiation. Sov. Phys. JETP, 59(2), 442–450.
Abstract: The effect of heating of electrons relative to phonons is observed and investigated in a superconducting film that is made resistive by current and by an external magnetic field. The effect is manifested by an increase of the film resistance under the influence of the electromagnetic radiation, and is not selective in the frequency band 10^10-10^15 Hz. The independence of the effect of frequency under conditions of strong scattering by static defects is attributed to the decisive role of electron-electron collisions in the distribution function. The experimentally obtained characteristic time of resistance variation near the superconducting transition corresponds to the relaxation time of the order parameter, while at lower temperatures and fields it corresponds to the time of the inelastic electron-phonon interaction.
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