Superconductive photoelectric switch

Abstract

A first type of superconductive photoelectric device is provided by a superconductive thin film located between two electrodes. The superconductive thin film is one which has a photo-conductive effect and converts from a normally conducting state to a superconductive state in response to light irradiation. The superconductive thin film is preferably formed of a compound semiconductor of Pb chalcogenide added with Pb and/or In added beyond the stoicheometry of the compound semiconductor, such as Pb.sub.1-x Sn.sub.x Te+In, so as to generate precipitations of Pb. A second type of superconductive photoelectric device is provided by a photo-conductive material formed of Pb.sub.1-x Sb.sub.x Te filled in a gap between two superconductive electrodes, where the gap width is shorter than 500 times of a coherence length. In either the first-or second type, when an infrared light is irradiated onto the photo-conductive region at a predetermined temperature, the coherence length of the superconductivity is extended so as to convert from a normally conducting state to a superconductive state. When ON/OFF irradiated with a light shorter than 0.8 .mu.m, a material Pb.sub.1-x Sn.sub.x Te without In switches between the normally conducting state and the superconductive state. With In added, the material persistently converts from the normally conducting state to the superconductive state.