A SiC Planar MOSFET with an Embedded MOS-Channel Diode to Improve Reverse Conduction and Switching

A novel split-gate SiC MOSFET with an embedded MOS-channel diode for enhanced third-quadrant and switching performances is proposed and studied using TCAD simulations in this paper. During the freewheeling period, the MOS-channel diode with a low potential barrier constrains the reverse current flow through it. Therefore, the suggested device not only has a low diode cut-in voltage but also entirely suppresses the intrinsic body diode, which will cause bipolar deterioration. In order to clarify the barrier-lowering effect of the MOS-channel diode, an analytical model is proposed. The calibrated simulation results demonstrate that the diode cut-in voltage of the proposed device is decreased from the conventional voltage of 2.7 V to 1.2 V. In addition, due to the split-gate structure, the gate-to-drain charge (Q(GD)) of the proposed device is 20 nC/cm(2), and the reverse-transfer capacitance (C(GD)) is 14 pF/cm(2), which are lower than the Q(GD) of 230 nC/cm(2) and the C(GD) of 105 pF/cm(2) for the conventional one. Therefore, a better high-frequency figure-of-merit and lower switching loss are obtained.