Records |
Author |
Sergeev, A.; Semenov, A.; Trifonov, V.; Karasik, B.; Gol'tsman, G.; Gershenzon, E. |
Title |
Heat transfer in YBaCuO thin film/sapphire substrate system |
Type |
Journal Article |
Year |
1994 |
Publication |
J. Supercond. |
Abbreviated Journal |
J. Supercond. |
Volume |
7 |
Issue |
2 |
Pages |
341-344 |
Keywords |
YBCO films |
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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0896-1107 |
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1647 |
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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 |
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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0163-1829 |
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PMID:10009690 |
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1648 |
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Author |
Gousev, Y. P.; Semenov, A. D.; Gol'tsman, G. N.; Sergeev, A. V.; Gershenzon, E. M. |
Title |
Electron-phonon interaction in disordered NbN films |
Type |
Journal Article |
Year |
1994 |
Publication |
Phys. B Condens. Mat. |
Abbreviated Journal |
Phys. B Condens. Mat. |
Volume |
194-196 |
Issue |
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Pages |
1355-1356 |
Keywords |
NbN films |
Abstract |
Electron-phonon interaction time has been investigated in disordered films of NbN. A temperatures below 5.5 K tau_eph ~ T -1"6 which is attributed to the renormalisation of phonon spectrum in thin films. |
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0921-4526 |
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1649 |
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Author |
Semenov, A. D.; Goghidze, I. G.; Gol’tsman, G. N.; Sergeev, A. V.; Gershenzon, E. M. |
Title |
Evidence for the spectral dependence of nonequilibrium picosecond photoresponse of YBaCuO thin films |
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Journal Article |
Year |
1993 |
Publication |
Appl. Phys. Lett. |
Abbreviated Journal |
Appl. Phys. Lett. |
Volume |
63 |
Issue |
5 |
Pages |
681-683 |
Keywords |
YBCO HTS detectors, nonequilibrium |
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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0003-6951 |
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1655 |
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Author |
Nebosis, R. S.; Heusinger, M. A.; Schatz, W.; Renk, K. F.; Gol’tsman, G. N.; Karasik, B. S.; Semenov, A. D.; Gershenzon, E. M. |
Title |
Ultrafast photoresponse of a structured YBa2Cu3O7-δ thin film to ultrashort FIR laser pulses |
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Journal Article |
Year |
1993 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
Volume |
3 |
Issue |
1 |
Pages |
2160-2162 |
Keywords |
YBCO HTS detectors |
Abstract |
The authors have investigated the photoinduced voltage response of a current-carrying structured YBa2Cu3O7-δ thin film to ultrashort far-infrared (FIR) laser pulses in the frequency range from 0.7 THz to 7 THz. The detector has shown an almost constant sensitivity of 1 mV/W and a noise equivalent power of less than 5*10/sup -7/ W/ square root Hz. The temperature dependence of the decay time of the detector signal was studied for temperatures around the transition temperature of the film ( approximately 80 K). For a detector temperature where dR/dT had its maximum, the authors observed bolometric signals with decay times of about 2 ns, and for lower temperatures they observed nonbolometric signals with decay times of approximately 120 ps; the duration of the nonbolometric signals was limited by the time resolution of the electronic registration equipment. |
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1658 |
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