Thin-film Josephson tunnel junctions with niobium electrodes

Josephson tunnel junctions based on Nb for the lower electrode and Pb as a counter electrode, have been extensively described in recent years. However, relatively little has been published on all Nb thin-film structures although this system is of interest because of the superior chemical and mechanical stability of Nb films in comparison to Pb. Some results are described on all Nb tunnel junctions (Nb/Nb), making comparison where relevant with Nb junctions having Pb counter electrodes. (Auth.)