A Low-Loss Diode Integrated SiC Trench MOSFET for Improving Switching Performance

A novel silicon carbide (SiC) asymmetric trench MOSFET with integrated low-loss diode (LLD-ATMOS) is proposed and investigated by numerical simulations to reduce switching loss and eliminate bipolar degradation of body diode. The N-channel region beneath the dummy gate provides a low barrier path to transport electrons form the N-drift layer to N+ source region, with the result that the forward conduction voltage drop is reduced from 3.5 V at 10 A of the pn body diode to 1.9 V at 10 A of the LLD-ATMOS. Furthermore, the reverse recovery charge (QRR) of LLD and the gate-to-drain capacitance (
${C}_{\text {gd}}$
) of LLD-ATMOS are 76% and 95% lower than those of the conventional asymmetric trench MOSFET (C-ATMOS). As a result, the turn-off and turn-on losses of LLD-ATMOS are reduced by 49% and 58%, respectively. The calculated high-frequency figure of merit (
$\text {HF-FOM} = {R}_{ {{\text{ON}}},\text {sp}} \times {C}_{\text {gd}}$
) of LLD-ATMOS is tremendously decreased to one-fourteenth of the value of C-ATMOS. In addition, a conduction band energy analysis model for the LLD is developed. The improved performances suggest that LLD-ATMOS is a competitive option in power electronic systems.