Properties of niobium-based Josephson tunnel junctions with a lead-indium alloy top electrode

A fabrication process for niobium-based Josephson superconductive tunnel junctions with a Pb/In alloy top electrode which showed very good mechanical and electrical properties and high oxide uniformity is described. The dependence of the junction parameters on the In-percentage in the alloy is also reported, and the results, in connection with data on the barrier composition, obtained via Auger electron-spectroscopy analysis, are discussed.