SiGe Semiconductor Devices for High-Performance Cryogenic Power Electronics

We propose to continue development of power semiconductor devices (diodes and transistors) for power-management and actuator-control circuits operating at cryogenic temperatures. Cryogenic power electronics can provide important benefits both for space and commercial applications: higher efficiency, reduced size, weight and complexity, and improved system reliability. Of primary importance to spacecraft is reduction or elimination of thermal control and its attendant power usage, weight, size and added electronics. We propose using the silicon-germanium (SiGe) materials system because of its powerful design flexibility, compatibility with silicon processing, and ability to combine desirable features of both silicon and germanium. Conventional Si-based electronics has not proved adequate for deep-cryogenic temperature (down to 30 K) power applications, whereas SiGe operates well down to these cryogenic temperatures. In Phase I we successfully fabricated metal-insulator-semiconductor (MIS) structures and heterojunction bipolar transistors (HBT), which are essential elements of advanced power devices to be developed in Phase II. The proposed SiGe cryogenic power devices are an innovation because there are presently no power semiconductor devices based on SiGe and designed for cryogenic applications.