Transient radiation response of jfets and misfets at cryogenic temperatures

Abstract

This paper provides experimental and analytical data on the transient radiation response and d.c. electrical characteristics of JFETs and MISFETs at cryogenic temperatures. Experimental measurements were performed on commercially available silicon devices over the temperature range 4.2°K to 300°K. A 2 Mev Flash X-ray Facility was used for the photocurrent measurements. The theoretical effort provides a compilation of silicon properties at cryogenic temperatures and scopes out the first-order temperature dependence of JFETs and MISFETs. It was observed that (a) the MISFET functioned well at channel temperatures down to 4.2°K, (b) the JFET would not conduct current at channel temperatures below 50°K (though it could be held on by self-heating at case temperatures down to 4.2°K), (c) the photocurrents of each device enhanced by a factor of 2 or more at temperatures below 40°K. The results are in general agreement with first-order theory, but many problems must be resolved to achieve adequate modeling and understanding of relevant phenomena.