Temperature-Dependent Degradation of SiC Schottky Diode Inhibition Effect on SiC MOSFET Body Diode Reverse Recovery Current

Integrating an external Silicon Carbide (SiC) Schottky barrier diode (SBD) significantly enhances the reverse recovery performance of the power converters using only the body diode of SiC MOSFETs. The SBD reduces the current spike on the MOSFETs and improves the device’s electromagnetic compatibility. However, the higher junction temperature degrades the SBD inhibition effect on the reverse recovery current. Existing research lacks a theoretical explanation of this mechanism. In this study, the degradation of the SBD inhibition effect is explained by the temperature-dependent current distribution of the body diode and SBD. The current distribution of a 1200 V SiC MOSFET with an external 1200 V SiC SBD is investigated through the double pulse test from -30°C to 175°C. The results demonstrate that the degradation of the SBD inhibition effect occurs simultaneously when the body diode conducts a freewheeling current at temperatures exceeding 75°C. The proposed indicator of this degradation is a negative temperature coefficient load current threshold value.