Oxide superconductor Josephson junction and fabrication method therefor

A method of fabricating an oxide superconductor Josephson junction comprising:

• the steps of forming a bonding pad by depositing Cr or Au by evaporation on part of a substrate;
• the step of forming a first superconducting electrode layer of a thin film of BaPb.sub.1-x Bi.sub.x O.sub.3 (wherein 0.05.ltoreq.x.ltoreq.0.3) which is an oxide with perovskite structure including the steps of forming by sputtering a thin film of said BaPb.sub.1-x Bi.sub.x)O.sub.3 on a cooled substrate arranged in opposition to a ceramic target of BaPb.sub.1-x Bi.sub.x O.sub.3 (wherein 0.05.ltoreq.x.ltoreq.0.3) which is an oxide with perovskite structure and annealing the thin film of BaPb.sub.1-x Bi.sub.x O.sub.3 formed in said steps to turn it into a superconducting material;
• the step of forming a barrier layer on the surface of said first superconducting electrode layer under the condition that said substrate is cooled, said barrier layer consisting of one member selected from the group consisting of BaSnO.sub.3, Ba.sub.1-y Sr.sub.y Pb.sub.1-x Bi.sub.x O.sub.3 (wherein 0.ltoreq.x.ltoreq.0.3, y>0.3) and BaPb.sub.1-x (A.sub.1-y Bi.sub.y).sub.x O.sub.3 (wherein A is at least one member selected from the group consisting of V, Nb, Ta and Sb;
• and 0.ltoreq.y.ltoreq.0.5), all being oxides with perovskite structures;
• the step of forming a second superconducting electrode layer of BaPb.sub.1-x Bi.sub.x O.sub.3 (wherein 0.05.ltoreq.x.ltoreq.0.3) which is an oxide with perovskite structure including the steps of forming a thin film of said BaPb.sub.1-x Bi.sub.x O.sub.3 by sputtering on the surface of said barrier layer under the condition that said substrate is cooled and annealing the BaPb.sub.1-x Bi.sub.x O.sub.3 thin film formed in said steps to turn it into a superconducting material;
• and
• the step of connecting said bonding pad and said second superconducting electrode layer including the step of depositing by lift off evaporation between said bonding pad and said second superconducting electrode layer BaPb.sub.1-x Bi.sub.x O.sub.3 which is an oxide with perovskite structure and the step of annealing BaPb.sub.1-x Bi.sub.x O.sub.3 thus deposited for rendering the same superconducting.