Grain boundary junction devices using high t.sub.c superconductors

Abstract

High T.sub.c superconducting devices are described in which controlled grain boundaries in a layer of the superconductors forms a weak link or barrier between superconducting grains of the layer. A method is described for reproducibly fabricating these devices, including first preparing a substrate to include at least one grain boundary therein. A high T.sub.c superconductor layer is then epitaxially deposited on the substrate in order to produce a corresponding grain boundary in the superconducting layer. This superconducting layer is then patterned to leave at least two regions on either side of the grain boundary, the two regions functioning as contact areas for a barrier device including the grain boundary as a current flow barrier. Electrical contacts can be made to the superconducting regions so that bias currents can be produced across the grain boundary which acts as a tunnel barrier or weak link connection.