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Karasik BS, Gol'tsman GN, Voronov BM, Svechnikov SI, Gershenzon EM, Ekstrom H, et al. Hot electron quasioptical NbN superconducting mixer. IEEE Trans Appl Supercond. 1995;5(2):2232–5.
Abstract: Hot electron superconductor mixer devices made of thin NbN films on SiO/sub 2/-Si/sub 3/N/sub 4/-Si membrane have been fabricated for 300-350 GHz operation. The device consists of 5-10 parallel strips each 5 /spl mu/m long by 1 /spl mu/m wide which are coupled to a tapered slot-line antenna. The I-V characteristics and position of optimum bias point were studied in the temperature range 4.5-8 K. The performance of the mixer at higher temperatures is closer to that predicted by theory for uniform electron heating. The intermediate frequency bandwidth versus bias has also been investigated. At the operating temperature 4.2 K a bandwidth as wide as 0.8 GHz has been measured for a mixer made of 6 nm thick film. The bandwidth tends to increase with operating temperature. The performance of the NbN mixer is expected to be better for higher frequencies where the absorption of radiation should be more uniform.
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de Lange G, Kuipers JJ, Klapwijk TM, Panhuyzen RA, van de Stadt H, de Graauw MWM. Superconducting resonator circuits at frequencies above the gap frequency. J. Appl. Phys.. 1995;77(4):1795–804.
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Parvitte B, Thomas X, Courtois D. Wide band (2.5 GHz) infrared heterodyne spectrometer. Int. J. Infrared and Millimeter Waves. 1995;16(9):1533–40.
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Ptitsina NG, Chulkova GM, Gershenzon EM. Influence of the interference of electron-phonon and electron-impurity scattering on the conductivity of unordered Nb films. JETP. 1995;80(5):960–4.
Abstract: The temperature dependence of the resistivity of Nb thin films has been studied at T=4.2-300 K. It has been shown that quantum interference between electron-phonon and electron-impurity scattering determines the temperature dependence of the resistivity of the films investigated over a broad temperature range. The magnitude of the contribution of the electron-phonon-impurity,interference is described satisfactorily by the theory developed by Reizer and Sergeev {Zh. Eksp. Teor. Fiz. 92,2291 (1987) [Sov. Phys. JETP 65, 1291 (1987)l). The interaction constants of electrons with longitudinal and transverse phonons in Nb films have been determined for the first time by comparing the experimental data with the theory. The values of the constants obtained are consistent with the data on the inelastic electron-phonon scattering times in the films investigated. The contribution of the transverse phonons is dominant both in the interference correction to the resistivity and in the electron energy relaxation.
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Hans Ekstrom, Karasik BS, Kollberg EL, Sigfrid Yngvesson. Conversion gain and noise of niobium superconducting hot–electron–mixers. IEEE Trans. Appl. Supercond.. 1995;43(4):938–47.
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