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 (15∗) chip size, thinner active layer thickness and higher power density.