Steady-state over-current safe operation area (SOA) of the SiC MOSFET at cryogenic and room temperatures

The over-current withstanding ability of the silicon carbide (SiC) based metal-oxidesemiconductor field effect transistor (MOSFET) is really important for the survival during over-load and short-circuit disturbances. This article investigates the experimental characterizations of the steady-state over-current safe operation area (SOA) of SiC MOSFET at both the cryogenic temperature (77 K) and room temperature (300 K). Benefiting from the sufficient cooling power by the liquid nitrogen around devices, the cryogenic SiC MOSFET can have over 10 times longer than the over-current withstanding time at room temperature. For practical applications in highperformance SiC-based power conversions and superconductor-semiconductor-coupled systems, 4 over current-dependent functions have been derived to predict the withstanding time and power dissipation at both 77 K and 300 K. Considering the lowest on-state resistance during the transient over-current process of first increasing and then decreasing, a new SOA concept is further used to judge the safety threshold of the SiC MOSFET and the subsequent switch-off action. The new method and procedure can effectively predict the potential safety issue of over heat, and make the switching-off actions in advance, which can prevent the late protection action due to the hardware/software delays. Our experimental/theoretical investigations and the new analysis can also be regarded as general methods which are applicable to study other types of MOSFETs and build corresponding protection schemes.