SIS technology development to serve Next Generation receivers for ALMA

Paper i proceeding, 2022

Modern radio astronomy demands for broadband receiver systems. For SIS mixers, this translates into objective to employ superconducting tunnel junctions with a very low RnA and low specific capacitance. The traditionally used Nb/AlO x /Nb junctions have largely approached their physical limit of minimizing those parameters. It is commonly recognized that it is AlN-barrier junctions, which are needed for further progressing of the broadband SIS mixer instrumentation for radio astronomy. In this work, we present the progress in development of the process for high quality Nb/Al-AlN/Nb superconducting tunnel (SIS) junctions’ fabrication and their characterization in terms of their specific capacitance.