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Развитие технологии изготовления NbN HEB-смесителей с малым разбросом DC- и RF-параметров для создания матричных приемников терагерцового диапазона
The influence of the magnetron deposition process parameters for a thin 4–5 nm NbN superconducting niobium nitride film and the NbN HEB mixer fabrication technology on the spread of their key parameters was experimentally studied to minimize this spread. In addition to optimizing the NbN film deposition process, uniformity of the NbN HEB mixer parameters was achieved through surface preparation of the Si substrate and the use of an in-situ deposited Au layer with the NbN film as a contact with the planar THz antenna. NbN HEB mixers fabricated using the optimized process had virtually identical R(T) characteristics, with a spread of critical temperature and normal resistance no greater than 0.15 K and 2 Ω, respectively. The noise temperature at the local oscillator frequency of 2.52 THz was 800 K, with a spread of 150 K from sample to sample. The mixer noise bandwidth at
T= 4.5 K averaged 7 GHz.