Microstructure Damage for Single-Event Leakage Current II in SiC MOSFETs Induced by Heavy Ion

This article investigates the electrical characteristics and microstructure damage associated with single-event leakage current II (SELC II) degradation in silicon carbide (SiC) MOSFETs subjected to 181Ta heavy-ion irradiation. For 1200-V SiC MOSFETs, SELC II degradation was observed at drain biases between 450 and 600 V. Postirradiation, two distinct leakage current paths were identified in SiC MOSFETs affected by SELC II degradation when a drain bias was applied. The drain-source leakage path, which operates independent of gate oxide damage, appeared only after a specific voltage threshold was surpassed. Similar electrical behavior observed in both irradiated and postirradiated SiC MOSFETs and p-i-n diodes indicates that the p-n junction plays a key role in the SELC II degradation of SiC MOSFETs. High-resolution TEM analysis also reveals that, for the first time, SELC II-induced microstructural damage, including cavities, dislocations, and misorientations, concentrated at the interface between the P-well region and the N-epilayer in SiC MOSFETs.