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Maezawa H. Application of superconducting hot-electron bolometer mixers for terahertz-band astronomy. IEICE Trans. Electronics. 2015;98(3):196–206.
Abstract: Recently, a next-generation heterodyne mixer detector – a hot electron bolometer (HEB) mixer employing a superconducting microbridge – has gradually opened up terahertz-band astronomy. The surrounding state-of-the-art technologies including fabrication processes, 4 K cryostats, cryogenic low-noise amplifiers, local oscillator sources, micromachining techniques, and spectrometers, as well as the HEB mixers, have played a valuable role in the development of super-low-noise heterodyne spectroscopy systems for the terahertz band. The current developmental status of terahertz-band HEB mixer receivers and their applications for spectroscopy and astronomy with ground-based, airborne, and satellite telescopes are presented.
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Ryabchun SA, Tretyakov IV, Finkel MI, Maslennikov SN, Kaurova NS, Seleznev VA, et al. NbN phonon-cooled hot-electron bolometer mixer with additional diffusion cooling. In: Proc. 20th Int. Symp. Space Terahertz Technol. Charlottesville, USA; 2009. p. 151–4.
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Tretyakov IV, Ryabchun SA, Maslennikov SN, Finkel MI, Kaurova NS, Seleznev VA, et al. NbN HEB mixer: fabrication, noise temperature reduction and characterization. In: Proc. Basic problems of superconductivity. Moscow-Zvenigorod; 2008.
Abstract: We demonstrate that in the terahertz region superconducting hot-electron mixers offer the lowest noise temperature, opening the possibility of using HTS's in the future to fabricate these devices. Specifically, a noise temperature of 950 K was measured for the receiver operating at 2.5 THz with a NbN HEB mixer, and a gain bandwidth of 6 GHz was measured at 300 GHz near Tc for the same mixer.
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Ryabchun SA, Tretyakov IV, Pentin IV, Kaurova NS, Seleznev VA, Voronov BM, et al. Low-noise wide-band hot-electron bolometer mixer based on an NbN film. Radiophys. Quant. Electron.. 2009;52(8):576–82.
Abstract: We develop and study a hot-electron bolometer mixer made of a two-layer NbN–Au film in situ deposited on a silicon substrate. The double-sideband noise temperature of the mixer is 750 K at a frequency of 2.5 THz. The conversion efficiency measurements show that at the superconducting transition temperature, the intermediate-frequency bandwidth amounts to about 6.5 GHz for a mixer 0.112 μm long. These record-breaking characteristics are attributed to the improved contacts between a sensitive element and a helical antenna and are reached due to using the in situ deposition of NbN and Au layers at certain stages of the process.
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Рябчун СА, Третьяков ИВ, Пентин ИВ, Каурова НС, Селезнев ВА, Воронов БМ, et al. Малошумящий широкополосный терагерцовый смеситель на эффекте электронного разогрева в плёнке NbN. Известия высших учебных заведений. Радиофизика. 2009;52(8):641–8.
Abstract: Разработан и исследован смеситель на горячих электронах, изготовленный из двуслойной плёнки NbN-Au, осаждённой на кремневую подложку in situ. Двухполосная шумовая температура устройства составила 750 К на частоте 2.5 ТГц. Измерения эффективности преобразования для смесителя длиной 0.112 мкм вблизи температуры сверхпроводящего перехода показали полосу промежуточных частот около 6.5 ГГц. Эти результаты являются рекордными и были получены за счёт улучшения контактов между чувствительным элементом и спиральной антенной при замене технологического маршрута с нанесением слоёв NbN и Au в отдельных процессах на технологический процесс, в котором данные слои наносятся in situ без нарушения вакуума.
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