Patent ID: 8032196

Claim:
A Josephson device comprising: a substrate having a surface; a first superconducting electrode layer formed on the surface of the substrate; an insulator formed on the first superconducting electrode layer and having a penetration hole penetrating the insulator layer in a direction taken along a thickness of the insulator layer; a barrier layer deposited on the first superconducting electrode layer and within the penetration hole; and a second superconducting electrode layer filling the penetration hole and covering the barrier layer and the insulator layer, wherein said first and second superconducting electrode layers are made of an oxide superconductor material having (RE) 1 (AE) 2 Cu 3 O y as a main component, where an element RE is at least one element selected from a group consisting of Y, La, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb and Lu, and an element AE is at least one element selected from a group consisting of Ba, Sr and Ca; and said barrier layer is made of a material that includes the element RE, the element AE, Cu and oxygen, where in cations within the material forming the barrier layer, a Cu content is in a range of 35 At. % to 55 At. % and an RE content is in a range of 12 At. % to 30 At. %, and the barrier layer has a composition different from compositions of the first and second superconducting electrode layers.