SiGe and Ge Cryogenic Power Transistors

Abstract

We have undertaken development of power semiconductor devices based on SiGe and Ge, intended for operation over a wide temperature range, from room temperature down to deep cryogenic temperatures, ~30 K (~ -240{degree sign}C). We summarize results for Ge diodes (~10 A/400 V), Ge junction field-effect transistors (Ge JFETs, ~0.5 A/30 V), Ge metal-insulator field-effect transistors (Ge MIS-FETs ~1 A/20 V) and SiGe heterojunction bipolar transistors (SiGe HBTs, ~10 A/50 V). As a practical demonstration, we have used SiGe HBTs and SiGe diodes as the active devices in 100-W power-conversion circuits, operating from room temperature down to ~30 K (~ -240{degree sign}C) with increased efficiency as temperature de-creases. Our developments demonstrate the potential of alternative semiconductor materials to provide excellent performance for power applications down to deep cryogenic temperatures.