Novel SiGe Devices for Cryogenic Power Electronics

Power generation, power distribution and electric propulsion on ships and aerospace vehicles could be made smaller, lighter, more efficient, more versatile, and lower maintenance by operating these systems—partly or entirely—at cryogenic temperatures. Our goal is to demonstrate the advantages of cryogenic operation in regard to electronic components, specifically semiconductor devices (power diodes and transistors) based on the silicon-germanium (SiGe) materials system. Our choice of SiGe is based on: first, its versatility in device design through bandgap engineering and selective placement, which enables optimizing device performance at cryogenic temperatures; and, second, its high compatibility with standard semiconductor fabrication. Our technical approach comprises four parts: (1) device simulation, (2) device fabrication and characterization, (3) evaluation of the devices in power circuits, (4) iteration of this simulation-fabrication-characterization-evaluation cycle. Our technical goal for Phase II is to further develop SiGe heterojunction diodes into a mature product for insertion into cryogenic power-management subsystems, such as those being developed at MTECH Laboratories. Target requirements are 10-100 A, 1000-1500 V diodes operating temperatures down to ~60 K and having performance superior to available state-of-the-art Si diodes.