|
|
Hübers H-W, Schubert J, Krabbe A, Birk M, Wagner G, Semenov A, et al. Parylene anti-reflection coating of a quasi-optical hot-electron-bolometric mixer at terahertz frequencies. Infrared Physics & Technology. 2001;42(1):41–7.
Abstract: Parylene C was investigated as anti-reflection coating for silicon at terahertz frequencies. Measurements with a Fourier-transform spectrometer show that the transmittance of pure silicon can be improved by about 30% when applying a layer of Parylene C with a quarter wavelength optical thickness. The 10% bandwidth of this coating extends from 1.5 to 3 THz for a center frequency of 2.3–2.5 THz, where the transmittance is constant. Heterodyne measurements demonstrate that the noise temperature of a hot-electron-bolometric mixer can be reduced significantly by coating the silicon lens of the hybrid antenna with a quarter wavelength Parylene C layer. Compared to the same mixer with an uncoated lens the improvement is about 30% at a frequency of 2.5 THz.
|
|
|
|
Gershenzon EM, Gol'tsman GN, Karasik BS, Semenov AD. Measurement of the energy gap in the compound YBaCu3O9-δ on the basis of the IR absorption spectrum. JETP Lett. 1987;46(5):237–8.
Abstract: For the first time the long-wave infrared absorption spectrum has been measured by means of the bolometric effect and energy gap for high-temperature superconducting ceramics YBa/sub 2/Cu/sub 3/O/sub 9-delta/ has been determined from absorption threshold. 2delta/kT/sub c/ value is equal to 0.6.
|
|
|
|
Gershenzon EM, Gershenzon ME, Gol'tsman GN, Karasik BS, Semenov AD, Sergeev AV. Light-induced heating of electrons and the time of the inelastic electron-phonon scattering in the YBaCuO compound. JETP Lett. 1987;46(6):285–7.
Abstract: For the first time, measurements have been made on the electron energy relaxation time due to the electron--phonon interaction in films of the YBaCuO superconductor. The results indicate a significant intensification of the electron--phonon interaction in this compound as compared with normal superconducting metals.
|
|
|
|
Sergeev AV, Semenov AD, Kouminov P, Trifonov V, Goghidze IG, Karasik BS, et al. Transparency of a YBa2Cu3O7-film/substrate interface for thermal phonons measured by means of voltage response to radiation. Phys Rev B Condens Matter. 1994;49(13):9091–6.
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.
|
|
|
|
Aksaev EE, Gershenzon EM, Gol'tsman GN, Semenov AD, Sergeev AV. Interaction of electrons with thermal phonons in YBa2Cu3O7-δ films at low temperatures. JETP Lett. 1989;50(5):283–6.
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.
|
|
