4H-SiC Double-Trench MOSFET with Side Wall Heterojunction Diode for Enhanced Reverse Recovery Performance

Abstract

In this study, a novel 4H-SiC double-trench metal-oxide semiconductor field-effect transistor (MOSFET) with a side wall heterojunction diode is proposed and investigated by conducting numerical technology computer-aided design simulations. The junction between P+ polysilicon and the N-drift layer forming a heterojunction diode on the side wall of the source trench region suppresses the operation of the PiN body diode during the reverse conduction state. Therefore, the injected minority carriers are completely suppressed, reducing the reverse recovery current by 73%, compared to the PiN body diodes. The switching characteristics of the proposed MOSFET using the heterojunction diode as a freewheeling diode was compared to the power module with a conventional MOSFET and an external diode as a freewheeling diode. It is shown that the switching performance of the proposed structure exhibits equivalent characteristics compared to the power module, enabling the elimination of an external freewheeling diode in the power system.