Single-pulse avalanche mode operation of 10-kV/10-A SiC MOSFET

The high-voltage silicon carbide MOSFET is a state-of-the-art solution for increasing power density and efficiency in power electronics; nonetheless, a full-scope of failure modes during extreme operating condition has not been established. Past efforts evaluated short-circuit capability of 10-kV silicon carbide MOSFET, however, in this manuscript, the single-pulse avalanche mode operation of a research-grade 10-kV/10-A silicon carbide MOSFET is explored for the first time. A decoupled unclamped inductive circuit was selected for evaluation, and avalanche energy was increased until catastrophic failure occurred. The maximum tolerable avalanche energy was measured to be 2.84 J corresponding to an energy density of 8.8 J·cm−2. This result was compared with 1.2-kV silicon carbide MOSFETs to evaluate device robustness. Post failure analysis included: estimation of junction temperature, scanning electron microscopy, and focused ion beam cut. Peak junction temperature of 1010 °C was estimated using a thermal RC model and measurement results suggested gate degradation as the primary mechanism responsible for device destruction. Microscopy of the device validated gate failure which occurred at, or beneath, the gate metallization. A narrow cavity with-in the failure region was discovered during failure analysis and is hypothesized to have protruded the epitaxial region of the semiconductor.