FETs with superconducting channels

The authors consider the implications of inducing superconducting properties in the channel of an FET by using superconductors as the source and drain metallizations. Under some circumstances the semiconductor source and drain regions can themselves become superconducting due to the proximity effect, i.e., the penetration of Cooper pairs into normal material at the interface with a superconductor. The proximity-effect regions can overlap if the channel is short enough, making the device a Josephson weak link in which a gate controls both superconductive and normal currents. The authors review the basic device concept and electrical characteristics, discuss several important materials-related issue, examine the present experimental and theoretical situation, and discuss the potential for applications. They describe recent work on superconducting In_0.47Ga_0.53As JFETs (junction FETs) that addresses several of the issues raised by the present discussion.