Fabrication process of Nb/Al/Nb SNS Josephson junctions for superconducting electronics applications

Overdamped Josephson junctions are gaining interest in many fields of superconducting electronics. The characteristic voltage ICRN is the parameter limiting the highest possible speed and voltage resolution of the junctions. Nb/Al/Nb technology is a good candidate for these devices because of its wide range of characteristic voltages. In our laboratory we have so far fabricated Nb/Al/Nb SNS junctions having (a) high critical currents and smooth interfaces, (b) low critical currents and smooth interfaces, (c) low critical currents and rough interfaces. However, further improvements to this technology are still needed.