Cryogenic Power Electronics

High temperature superconductor (HTS) materials are being used in high-performance propulsion systems for naval ships, as well as power cables, motors, and generators. These systems require the use of power electronics to provide the power for the control systems. Power electronic systems contain digital and analog circuits, and the increasing complexity of power electronic systems required for deep space missions and naval electric-powered propulsion requires a new approach in material and processes to operate efficiently at cryogenic temperatures. The n-type metal oxide semiconductor field effect transistor (n-MOSFET) is the building block for both digital and analog circuits. Silicon (Si) is a good material for fabricating power MOSFET and electronic devices for operation from 300 K down to 77 K. Devices made from Si suffer from carrier freeze-out below 77 K. Silicon carbide (SiC) is another material suitable for power switch transistors; however, SiC devices suffer from carrier freeze-out at temperatures higher that that of Si. Technology Applications, Inc. (TAI) proposes to develop a dc-dc converter power module for a power system with the incorporation of HTS thin films for the passive and active elements. We propose the use of a SiGe heterostructure metal oxide semiconductor modulation doped field effect transistor (MOS-MODFET) as the active device in our dc-dc converter power module development.