Abstract: A superconducting device operable at temperatures in excess of 30° K. and a method for making the device are described. A representative device is an essentially coplanar SQUID device formed in a single layer of high Tc superconducting material, the SQUID device being operable at temperatures in excess of 60° K. High energy beams, for example ion beams, are used to convert selected portions of the high Tc superconductor to nonsuperconductive properties so that the material now has both superconductive regions and nonsuperconductive regions. In this manner a superconducting loop having superconducting weak links can be formed to comprise the SQUID device.

Abstract: A lateral THETA device formed of a sandwich of first and second layers of semiconductor material forming a heterojunction therebetween and a two dimensional carrier gas in the second layer. First and second spaced electrodes are disposed on the surface of the first layer for inducing first and second potential barriers to the flow of charge carriers in the carrier gas. Ohmic contacts are deposited in the base region defined between the electrodes and in the emitter and collector regions defined on opposing sides of the electrodes. The width of the first electrode is formed narrow enough so that the first potential barrier beneath the electrode permits tunnelling of charge carriers into the base region. The width of the second electrode is wide enough so that the second potential barrier prevents tunnelling. Electrons tunnelling through the first barrier are hot and ballistically move through the base region to the collector.