Semenov, A. D., Gousev, Y. P., Nebosis, R. S., Renk, K. F., Yagoubov, P., Voronov, B. M., et al. (1996). Heterodyne detection of THz radiation with a superconducting hot‐electron bolometer mixer. Appl. Phys. Lett., 69(2), 260–262.
Abstract: We report on the use of a superconducting hot‐electron bolometer mixer for heterodyne detection of terahertz radiation. Radiation with a wavelength of 119 μm was coupled to the mixer, a NbN microbridge, by a hybrid quasioptical antenna consisting of an extended hyperhemispherical lens and a planar logarithmic spiral antenna. We found, at an intermediate frequency of 1.5 GHz, a system double side band noise temperature of ≊40 000 K and conversion losses of 25 dB. We also discuss the possibilities of further improvement of the mixer performance.
|
|
Ellison, B. N., Maddison, B. J., Matheson, D. N., Oldfield, M. L., Marazita, S., Crowe, T. W., et al. (1996). First results for a 2.5 THz Schottky diode waveguide mixer. In Proc. 7th Int. Symp. Space Terahertz Technol. (494). Charlottesville, Virginia, USA.
|
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.
|
Chulcova, G. M., Ptitsina, N. G., Gershenzon, E. M., Gershenzon, M. E., & Sergeev, A. V. (1996). Effect of the interference between electron-phonon and electron-impurity (boundary) scattering on resistivity Nb, Al, Be films. In Czech J. Phys. (Vol. 46, pp. 2489–2490).
Abstract: The temperature dependence of the resistivity of thin Nb, Al, Be films has been studied over a wide temperature range 4-300 K. We have found that the temperature-dependent correction to the residual resistivity is well described by the sum of the Bloch-Grüneisen term and the term originating from the interference between electron-phonon and electron-impurity scattering. Study of the transport interference phenomena allows to determine electron-phonon coupling in disordered metals. The interference term is proportional to T2 and also to the residual resistivity and dominates over the Bloch-Grüneisen term at low temperatures (T<40 K).
|
Verevkin, A. A., Ptitsina, N. G., Smirnov, K. V., Gol’tsman, G. N., Gershenzon, E. M., & Ingvesson, K. S. (1996). Direct measurements of energy relaxation times on an AlGaAs/GaAs heterointerface in the range 4.2–50 K. JETP Lett., 64(5), 404–409.
Abstract: The temperature dependence of the energy relaxation time τe (T) of a two-dimensional electron gas at an AlGaAs/GaAs heterointerface is measured under quasiequilibrium conditions in the region of the transition from scattering by acoustic phonons to scattering with the participation of optical phonons. The temperature interval of constant τe, where scattering by the deformation potential predominates, is determined. In the preceding, low-temperature region, where piezoacoustic and deformation-potential-induced scattering processes coexist, τ e decreases slowly with increasing temperature. Optical phonons start to participate in the scattering processes at T∼25 K (the characteristic phonon lifetime was equal to τLOτ4.5 ps). The energy losses calculated from the τe data in a model with an effective nonequilibrium electron temperature agree with the published data obtained under strong heating conditions.
|
