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Author Aksaev, E. E.; Gershenzon, E. M.; Gol'tsman, G. N.; Semenov, A. D.; Sergeev, A. V.
Title Interaction of electrons with thermal phonons in YBa2Cu3O7-δ films at low temperatures Type Journal Article
Year 1989 Publication JETP Lett. Abbreviated Journal JETP Lett.
Volume (down) 50 Issue 5 Pages 283-286
Keywords YBCO HTS films
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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Call Number Serial 1690
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Author Gershenzon, E. M.; Gol'tsman, G. N.; Multanovskii, V. V.; Ptitsyna, N. G.
Title Capture of photoexcited carriers by shallow impurity centers in germanium Type Journal Article
Year 1979 Publication Sov. Phys. JETP Abbreviated Journal Sov. Phys. JETP
Volume (down) 50 Issue 4 Pages 728-734
Keywords Ge, photoexcited carriers, shallow impurity centers
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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Call Number Serial 1720
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Author Fedorov, G. E.; Stepanova, T. S.; Gazaliev, A. S.; Gaiduchenko, I. A.; Kaurova, N. S.; Voronov, B. M.; Goltzman, G. N.
Title Asymmetric devices based on carbon nanotubes for terahertz-range radiation detection Type Journal Article
Year 2016 Publication Semicond. Abbreviated Journal Semicond.
Volume (down) 50 Issue 12 Pages 1600-1603
Keywords carbon nanotubes, CNT detectors
Abstract Various asymmetric detecting devices based on carbon nanotubes (CNTs) are studied. The asymmetry is understood as inhomogeneous properties along the conducting channel. In the first type of devices, an inhomogeneous morphology of the CNT grid is used. In the second type of devices, metals with highly varying work functions are used as the contact material. The relation between the sensitivity and detector configuration is analyzed. Based on the data obtained, approaches to the development of an efficient detector of terahertz radiation, based on carbon nanotubes are proposed.
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ISSN 1063-7826 ISBN Medium
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Notes Approved no
Call Number Serial 1776
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Author Sergeev, A. V.; Semenov, A. D.; Kouminov, P.; Trifonov, V.; Goghidze, I. G.; Karasik, B. S.; Gol’tsman, G. N.; Gershenzon, E. M.
Title Transparency of a YBa2Cu3O7-film/substrate interface for thermal phonons measured by means of voltage response to radiation Type Journal Article
Year 1994 Publication Phys. Rev. B Condens. Matter. Abbreviated Journal Phys. Rev. B Condens. Matter.
Volume (down) 49 Issue 13 Pages 9091-9096
Keywords YBCO films
Abstract The transparency of a film/substrate interface for thermal phonons was investigated for YBa2Cu3O7 thin films deposited on MgO, Al2O3, LaAlO3, NdGaO3, and ZrO2 substrates. Both voltage response to pulsed-visible and to continuously modulated far-infrared radiation show two regimes of heat escape from the film to the substrate. That one dominated by the thermal boundary resistance at the film/substrate interface provides an initial exponential decay of the response. The other one prevailing at longer times or smaller modulation frequencies causes much slower decay and is governed by phonon diffusion in the substrate. The transparency of the boundary for phonons incident from the film on the substrate and also from the substrate on the film was determined separately from the characteristic time of the exponential decay and from the time at which one regime was changed to the other. Taking into account the specific heat of optical phonons and the temperature dependence of the group velocity of acoustic phonons, we show that the body of experimental data agrees with acoustic mismatch theory rather than with the model that assumes strong diffusive scattering of phonons at the interface.
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ISSN 0163-1829 ISBN Medium
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Notes PMID:10009690 Approved no
Call Number Serial 1648
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Author Gershenzon, E. M.; Gol'tsman, G. N.; Ptitsina, N. G.
Title Population and lifetime of excited states of shallow impurities in Ge Type Journal Article
Year 1979 Publication Sov. Phys. JETP Abbreviated Journal Sov. Phys. JETP
Volume (down) 49 Issue 2 Pages 355-362
Keywords Ge, photothermal ionization, shallow impurities
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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Notes Approved no
Call Number Serial 1719
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