Trifonov, A., Tong, C. - Y. E., Grimes, P., Lobanov, Y., Kaurova, N., Blundell, R., et al. (2017). Development of A Silicon Membrane-based Multi-pixel Hot Electron Bolometer Receiver. In IEEE Trans. Appl. Supercond. (Vol. 27, 6).
Abstract: We report on the development of a multi-pixel
Hot Electron Bolometer (HEB) receiver fabricated using
silicon membrane technology. The receiver comprises a
2 × 2 array of four HEB mixers, fabricated on a single
chip. The HEB mixer chip is based on a superconducting
NbN thin film deposited on top of the silicon-on-insulator
(SOI) substrate. The thicknesses of the device layer and
handling layer of the SOI substrate are 20 μm and 300 μm
respectively. The thickness of the device layer is chosen
such that it corresponds to a quarter-wave in silicon at
1.35 THz. The HEB mixer is integrated with a bow-tie
antenna structure, in turn designed for coupling to a
circular waveguide,
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Korneeva, Y., Florya, I., Vdovichev, S., Moshkova, M., Simonov, N., Kaurova, N., et al. (2017). Comparison of hot-spot formation in NbN and MoN thin superconducting films after photon absorption. In IEEE Transactions on Applied Superconductivity (Vol. 27, 5).
Abstract: In superconducting single-photon detectors SSPD
the efficiency of local suppression of superconductivity and hotspot
formation is controlled by diffusivity and electron-phonon
interaction time. Here we selected a material, 3.6-nm-thick MoNx
film, which features diffusivity close to those of NbN traditionally
used for SSPD fabrication, but with electron-phonon interaction
time an order of magnitude larger. In MoNx detectors we study
the dependence of detection efficiency on bias current, photon
energy, and strip width and compare it with NbN SSPD. We
observe non-linear current-energy dependence in MoNx SSPD
and more pronounced plateaus in dependences of detection
efficiency on bias current which we attribute to longer electronphonon
interaction time.
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Titova, N., Kardakova, A. I., Tovpeko, N., Ryabchun, S., Mandal, S., Morozov, D., et al. (2017). Slow electron–phonon cooling in superconducting diamond films. IEEE Trans. Appl. Supercond., 27(4), 1–4.
Abstract: We have measured the electron-phonon energy-relaxation time, τ eph , in superconducting boron-doped diamond films grown on silicon substrate by chemical vapor deposition. The observed electron-phonon cooling times vary from 160 ns at 2.70 K to 410 ns at 1.8 K following a T -2-dependence. The data are consistent with the values of τ eph previously reported for single-crystal boron-doped diamond films epitaxially grown on diamond substrate. Such a noticeable slow electron-phonon relaxation in boron-doped diamond, in combination with a high normal-state resistivity, confirms a potential of superconducting diamond for ultrasensitive superconducting bolometers.
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Lusche, R., Semenov, A., Ilin, K., Siegel, M., Korneeva, Y., Trifonov, A., et al. (2014). Effect of the wire width on the intrinsic detection efficiency of superconducting-nanowire single-photon detectors. J. Appl. Phys., 116(4), 043906 (1 to 9).
Abstract: A thorough spectral study of the intrinsic single-photon detection efficiency in superconducting TaN and NbN nanowires with different widths has been performed. The experiment shows that the cut-off of the intrinsic detection efficiency at near-infrared wavelengths is most likely controlled by the local suppression of the barrier for vortex nucleation around the absorption site. Beyond the cut-off quasi-particle diffusion in combination with spontaneous, thermally activated vortex crossing explains the detection process. For both materials, the reciprocal cut-off wavelength scales linearly with the wire width where the scaling factor agrees with the hot-spot detection model.
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Nikoghosyan, A. S., Martirosyan, R. M., Hakhoumian, A. A., Makaryan, A. H., Tadevosyan, V. R., Goltsman, G. N., et al. (2018). Effect of absorption on the efficiency of THz radiation generation in a nonlinear crystal placed into a waveguide. Armenian J. Phys., 11(4), 257–262.
Abstract: The effect of THz radiation absorption on the efficiency of generation of coherent THz radiation in a nonlinear optical crystal placed into a metal rectangular waveguide is studied. The efficiency of the nonlinear conversion of optical laser radiation to the THz band is also a function of the phase-matching (PM) condition inside the nonlinear crystal. The method of partial filling of a metal waveguide with a nonlinear optical crystal is used to ensure phase matching. Phase matching was obtained by the proper choice of the thickness of the nonlinear crystal, namely the degree of partial filling of the waveguide. We have studied the THz radiation attenuation caused by the losses in both the metal walls of the waveguide and in the crystal, taking into account the dimension of the cross section of the waveguide, the degree of partial filling and its dielectric constant.
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