Infrared, Millimeter-Wave, and Terahertz Technologies

Noise performance of a 200–280 GHz mixer with Nb-AlN-NbN superconducting tunnel junctions

Boliang Liu, Dong Liu, Ming Yao, Jing Li, Sheng‐Cai Shi, Artem M. Chekushkin, M. Yu. Fominsky, Lyudmila V. Filippenko, V. P. Koshelets

Published Dec 16, 2022• 0 citations

Publisher

Abstract

Superconductor–insulator–superconductor (SIS) mixers remain the choice of heterodyne mixers for single-dish telescopes and interferometers at millimeter and submillimeter wavelengths. Compared with conventional Nb/AlOx/Nb superconducting tunnel junctions, Nb/AlN/NbN ones have larger gap voltage and may reach critical-current density beyond 10kA/cm2, which are both of particularly interest in developing broadband SIS mixers. Here we report on the design and measurement of an SIS mixer based on Nb/AlN/NbN parallel connected twin junctions (PCTJ) incorporating NbTiN/SiO2/Al microstrip circuit. The junctions have a gap voltage of 3.18mV and a critical-current density of 15kA/cm2. The measured receiver noise temperature reach 5hν/kB among 200-260GHz band, and the mixer’s fractional bandwidth is about 40% centered at 230GHz.

DOI: 10.1117/12.2642052

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