Power Cycling of Commercial SiC MOSFETs

The robustness under power cycling of three comparable silicon carbide MOSFETs in TO-247 packages from three different manufacturers is investigated, with silicon IGBTs serving as reference. The power cycling method, especially the junction temperature measurement and best practices to ensure its accuracy, is described. The results give insight into reliability and variability as well as aging behavior and failure modes. We find a large variability between samples, both in initial characteristics and measured cycling lifetime, as well as signs of semiconductor device degradation. There is a significant spread in the extent of the variability, in the average and minimum observed lifetime, as well as in the failure mode. Some samples fail quickly due to bond wire defects, some due to semiconductor degradation, while others show very long lifetimes.