Understanding and reduction of degradation phenomena in SiC power devices

Impacts of extended defects on performance and reliability of SiC power devices are reviewed. Threading dislocations in the state-of-the-art SiC wafers do not work as the major leakage paths and macroscopic defects generated during epitaxial process are more harmful. A basal plane dislocation is a killing defect in SiC bipolar devices because a Shockley-type stacking fault (SSF) is expanded from the dislocation when the electron-hole recombination energy is given. After classification of SSF-expansion patterns, the major types of SSFs (triangular-shaped and bar-shaped SSFs) and their origins are identified. Based on these understandings, two approaches to eliminate the “bipolar degradation” in SiC devices are presented. In particular, it is demonstrated that a “recombination-enhancing layer” is effective for substantial reduction of bipolar degradation in SiC devices.