Fabrication and properties of high Jclead—alloy Josephson junctions

High-current critical/density lead-alloy tunnel junctions were fabricated with junction areas of less than 1 µm². The relationship of junction quality, minimum resetting current Im, and energy-gap reduction to current critical/density Jcare investigated experimentally. The Jcdependence of Imis calculated taking into account the experimentally obtained quasi-particle current. The energy-gap reduction in high-Jcjunctions is explained by calculating the nonequilibrium quasi-particle distribution in the junction area. These calculated results are compared with the experimental data.