Characterization of high-voltage high-speed switching power semiconductors for high frequency cryogenically-cooled application

Cooling a converter to low temperatures, e.g. using cryogenic cooling, can significantly improve the efficiency and density of a power conversion system. For the development and optimization of a cryogenically-cooled converter, an understanding of power semiconductor characteristics is critical. This paper focuses on the characterization of high-voltage, high-speed switching, power semiconductors at cryogenic temperature. First, the testing setup for cryogenic temperature characterization is introduced. Three testing setups are established for cryogenic switch characterization, including: 1) on-state resistance and forward voltage drop of the body diode, 2) leakage current and breakdown voltage, and 3) switching characteristics. For each testing set up, the corresponding testing configurations, hardware setups, and practical considerations are summarized. Additionally, the test results at cryogenic temperature are illustrated and analyzed for 650-V Si CoolMOS. It is then demonstrated that when the cryogenic temperature test results are compared to that of room temperature, the device performance varies significantly; for example: on-state resistance reduces by 63%, breakdown voltage drops by 31%, switching time decreases and switching energy loss decreases by 26%. Furthermore, the peak dv/dt during transient switching at cryogenic temperature exceeds 100 V/ns which is comparable to the emerging wide bandgap Gallium Nitride devices.