Superconducting device having a superconducting channel formed of oxide

Abstract

A superconducting device comprises a substrate having a principal surface, a non-superconducting oxide layer having a similar crystal structure to that of an oxide superconductor formed on the principal surface, which can compensates the lattice mismatch between the substrate and the oxide superconductor, a superconducting source region and a superconducting drain region formed of c-axis oriented oxide superconductor thin films on the non-superconducting oxide layer, and an insulating region formed of a doped oxide superconductor on the non-superconducting oxide layer separating the superconducting source region and the superconducting drain region between them. On the insulating region an extremely thin superconducting channel formed of a c-axis oriented oxide superconductor thin film is arranged. The superconducting channel electrically connects the superconducting source region to the superconducting drain region, so that superconducting current can flow through the superconducting channel between the superconducting source region and the superconducting drain region. A gate electrode through a gate insulating layer is disposed on the superconducting channel for controlling the superconducting current flowing through the superconducting channel by the applied gate voltage. The superconducting source region, the superconducting drain region and the insulating region have the same thickness so that the extremely thin oxide superconductor thin film which constitutes the superconducting channel is formed flatwise.