Investigation on Single Pulse Avalanche Failure of 900V SiC MOSFETs

In this work, avalanche ruggedness and failure mechanisms of 900V SiC MOSFETs under single-pulse Unclamped Inductive Switching (UIS) test are investigated and compared with Si counterparts. It was found in this work that, due to the higher resistance to BJT latch-up, only uniform heating related device temperature limit failure exists in SiC MOSFETs. Experimental results also show that, SiC MOSFETs have 9 times higher avalanche energy per area and 50% higher avalanche current than Si MOSFETs in low inductance/short pulse condition. In large inductance/long pulse condition, SiC MOSFETs have shorter avalanche duration, lower avalanche current and only similar avalanche energy per area compared to Si, due to the much smaller (15x) chip size, thinner active layer thickness and higher power density.