Design Strategies for Rugged SiC Power Devices

This paper focuses on the design strategies for achieving adequate ruggedness of silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs). Currently available 1200 V MOSFETs from various vendors show a big variance in short circuit time, threshold voltage shift, and gate leakage currents. The short circuit (SC) test of three commercial TO-247 packaged MOSFETs with voltage ratings of 1200 V at room temperature show that the SC times are much lower than silicon devices. Threshold shifts under rated DC positive gate bias up to 100 hrs vary from 0.1 V to 0.5 V for different vendors. Fowler-Nordheim (FN) tunneling currents were measured as a function of gate bias and junction temperature. The FN gate leakage currents and temperature dependence are markedly different for various vendors. One vendor (for devices E and E’) stands out for best performance in all three respects.