A Low-Loss 1.2 kV SiC MOSFET with Improved UIS Performance

Abstract

In this article, a 1.2-kV-rated double-trench 4H-SiC MOSFET with an integrated low-barrier diode (DT-LBDMOS) is proposed which eliminates the bipolar degradation of the body diode and reduces switching loss while increasing avalanche stability. A numerical simulation verifies that a lower barrier for electrons appears because of the LBD; thus, a path that makes it easier for electrons to transfer from the N+ source to the drift region is provided, finally eliminating the bipolar degradation of the body diode. At the same time, the LBD integrated in the P-well region weakens the scattering effect of interface states on electrons. Compared with the gate p-shield trench 4H-SiC MOSFET (GPMOS), the reverse on-voltage (VF) is reduced from 2.46 V to 1.54 V; the reverse recovery charge (Qrr) and the gate-to-drain capacitance (Cgd) are 28% and 76% lower than those of the GPMOS, respectively. The turn-on and turn-off losses of the DT-LBDMOS are reduced by 52% and 35%. The specific on-resistance (RON,sp) of the DT-LBDMOS is reduced by 34% due to the weaker scattering effect of interface states on electrons. The HF-FOM (HF-FOM = RON,sp × Cgd) and the P-FOM (P-FOM = BV2/RON,sp) of the DT-LBDMOS are both improved. Using the unclamped inductive switching (UIS) test, we evaluate the avalanche energy of devices and the avalanche stability. The improved performances suggest that DT-LBDMOS can be harnessed in practical applications.

Keywords

• bipolar degradation
• silicon carbide (SiC) trench MOSFET
• integrated low-barrier diode
• unclamped inductive switching
• switching loss