A Novel Shield Gate 4H-SiC MOSFET with Reduced Reverse Recovery Losses

In this work, a novel integrated shield gate 4H-SiC MOSFET structure, which is mainly used to reduce the reverse recovery losses of the device, is proposed. Compared with integrating Schottky barrier diode or heterojunction diode in the device to reduce reverse recovery losses, the technology of introducing field plates in MOSFETs is more mature and economical. At the same time, the new structure studied ensures the gate oxide reliability of the 4H-SiC trench gate. According to the simulation of the electrical characteristics of the source-contacted shield gate device, the effects of multiple factors such as electric field distribution, carrier concentration, and peripheral circuit are comprehensively discussed, the phenomenon of smaller reverse recovery losses caused by the shield gate explained in detail. Compared with the conventional structure device, the peak reverse current, the peak overshoot voltage, and the reverse recovery losses for the source-contacted shield gate MOSFETs are reduced by 81.4%, 77.1%, and 65.1%, respectively.