New Definition of Critical Energy for SiC MOSFET Robustness under Short- Circuit Operations: the Repetitive Critical Energy

Previous research showed that Si devices could sustain a large number of Short Circuit (SC) events, as long as the energy dissipated during SC remains slightly below a given threshold (the so-called critical energy). In this paper, we show that this is not necessarily true for SiC MOSFETs, which can only withstand a few such SC events. This low robustness to repetitive short-circuit events is related to the gate degradation due to the cumulative carrier injection and leakage currents in the oxide. To ensure safe operation over a large number of SC events, we introduce a new parameter: the "repetitive critical energy", which corresponds to a SC energy low enough to avoid excessive temperature increase so as to limit the transient gate leakage current during SC events. Below this repetitive SC energy value, the SiC device is able to sustain a large number (more than 1000) of SC events.