Semenov, A., Richter, H., Hübers, H. - W., Smirnov, K., Voronov, B., & Gol'tsman, G. (2003). Development of terahertz superconducting hot-electron bolometer mixers. In Proc. 6th European Conf. Appl. Supercond. (Vol. 181, pp. 2960–2965).
Abstract: We present recent results of the development of phonon cooled hot-electron bolometric (HEB) mixers for airborne and balloon borne terahertz heterodyne receivers. Three iomportant issues have been addresses: the quality of NbN films the HEB mixers were made from, the spectral properties of the HEB mixers and the local oscillator power required for optical operation. Studies with an atomic force microscope indicate, that the performance of the HEB mixer might have been effected by the microstructure of the NbN film. Antenna gain and noise temperature were investigated at terahertz frequencies for a HEB embedded in either log-spiral or twin-slot feed antenna. Comparison suggests that at frequencies above 3 THz the spiral feed provides better overall performance. At 1.6 THz, a power of 2.5 µW was required from the local oscillator for optimal operation of the HEB mixer.
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Gol’tsman, G. N., Smirnov, K., Kouminov, P., Voronov, B., Kaurova, N., Drakinsky, V., et al. (2003). Fabrication of nanostructured superconducting single-photon detectors. IEEE Trans. Appl. Supercond., 13(2), 192–195.
Abstract: Fabrication of NbN superconducting single-photon detectors, based on the hotspot effect is presented. The hotspot formation arises in an ultrathin and submicrometer-width superconductor stripe and, together with the supercurrent redistribution, leads to the resistive detector response upon absorption of a photon. The detector has a meander structure to maximally increase its active area and reach the highest detection efficiency. Main processing steps, leading to efficient devices, sensitive in 0.4-5 /spl mu/m wavelength range, are presented. The impact of various processing steps on the performance and operational parameters of our detectors is discussed.
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Finkel, M., Vachtomin, Y., Antipov, S., Drakinski, V., Kaurova, N., Voronov, B., et al. (2003). Gain bandwidth and noise temperature of NbTiN HEB mixer. In Proc. 14th Int. Symp. Space Terahertz Technol. (pp. 276–285).
Abstract: We have determined that the gain bandwidth of phonon-cooled HEB mixer employing NbTiN films deposited on MgO layer over Si substrate is limited b y the escape of phonons to the substrate. The cut-off frequencies of 1 um long devices operating at T 71, based on 3.5 nm. 4 nm and 10 nm thick films amount to 400 Mk. 300 MHz, and 100 MHz, respectivel y . The gain bandwidth of 0.13 . um long devices fabricated from 3.5 nm thick film is larger and amounts to 0.8 GIL; at the optimal operating point and to 1.5 GIL: at larger bias. The increase of the gain bandwidth from 400 MHz up to 1.5 GH: with the change of bridge length is attributed to diffusion cooling. A double sideband noise temperature of 4000 K was obtained for heterodyne receiver utilizing pilot NbTiN HEB mixer (not optimized for normal state resistance) operating at the local oscillator frequency of 2.5 THz.
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Zwiller, V., Aichele, T., Seifert, W., Persson, J., & Benson, O. (2003). Generating visible single photons on demand with single InP quantum dots. Appl. Phys. Lett., 82(10), 1509–1511.
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Korneev, A., Lipatov, A., Okunev, O., Chulkova, G., Smirnov, K., Gol’tsman, G., et al. (2003). GHz counting rate NbN single-photon detector for IR diagnostics of VLSI CMOS circuits. Microelectronic Engineering, 69(2-4), 274–278.
Abstract: We present a new, simple to manufacture superconducting single-photon detector operational in the range from ultraviolet to mid-infrared radiation wavelengths. The detector combines GHz counting rate, high quantum efficiency and very low level of dark (false) counts. At 1.3–1.5 μm wavelength range our detector exhibits a quantum efficiency of 5–10%. The detector photoresponse voltage pulse duration was measured to be about 150 ps with jitter of 35 ps and both of them were limited mostly by our measurement equipment. In terms of quantum efficiency, dark counts level, speed of operation the detector surpasses all semiconductor counterparts and was successfully applied for CMOS integrated circuits diagnostics.
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