서강대학교

초록/요약

In this thesis, a novel 4H-SiC double-trench MOSFET with a side wall heterojunction diode is proposed and investigated by conducting TCAD simulations. The junction of P+ polysilicon on the side wall of the source trench region with an N-drift layer that forms the heterojunction diode (HJD) suppresses the operation of the PiN body diode in a reverse conduction state. Therefore, the injected minority carriers are completely suppressed and the reverse recovery current is reduced compared to the PiN body diode. We compared the switching characteristics of a proposed MOSFET that uses an HJD as a freewheeling diode with a power module consisting of a conventional MOSFET and an external SBD. The switching performance of the proposed structure shows equivalent characteristics compared to the power module, allowing the elimination of external freewheeling diode in the power system. In addition, proposed MOSFET has significantly improved SEB performance due to suppressed parasitic BJT operation. Therefore, the proposed structure can play an important role in the development of SEB hardening technology.