Investigation on Single Pulse Avalanche Failure of 1200V SiC MOSFETs at Different Temperatures

The avalanche ruggedness of SiC MOSFETs becomes a crucial issue to ensure the safe operation of the power conversion systems, especially under different temperature conditions. It's important to research on the avalanche failure of SiC, however, there is currently no clear conclusion on its failure mechanism. In this work, avalanche ruggedness and failure mechanism of SiC MOSFET in single-pulse Unclamped Inductive Switching (UIS) test were investigated through experimental evaluation at temperatures ranging from 25°C to 125°C, together with TCAD simulation. A 1200V planar commercialized SiC MOSFET device was chosen as a device under test (DUT) for this study. The results showed that the breakdown voltage of the SiC MOSFET exhibited a gradual upward trend with the increase of the temperature conditions. To study the avalanche failure mechanism of SiC MOSFETs more comprehensively, a TCAD simulation model had been established in this project and the DUT was decapped. A mechanism for SiC MOSFET failure (thermal failure) has been proposed.