Asymmetric Trench SiC MOSFET With Integrated Channel Accumulation Diode for Enhanced Reverse Conduction and Switching Characteristics

Abstract

A novel asymmetric trench Silicon Carbide Metal Oxide Semiconductor Field Effect Transistor (SiC MOSFET), featuring an integrated channel accumulation diode (CAD-MOS), has been proposed and investigated through numerical simulation. This innovative design aims to mitigate switching losses and eliminate the bipolar degradation of the body diode. The current spreading layer (CSL) channel, strategically positioned in the centre of the dummy gate, offers a low-barrier reverse conduction path. This represents a substantial advancement over the traditional PN body diode, significantly reducing the reverse conduction voltage drop from 2.84 V in the PN body diode to a mere 1.39 V in the CAD-MOS. Meanwhile, the reverse recovery charge of the CAD-MOS is reduced to 0.95 μC/cm², and the peak reverse recovery current stands at 45 A/cm². Compared to conventional asymmetrical trench SiC MOSFET (CON-MOS), the CAD-MOS exhibits a 68.1% reduction in reverse recovery charge and a 63.4% decrease in peak reverse recovery current. The split-gate design also reduces the device gate to source capacitance (C_GS), resulting in a 17.4% reduction in total switching losses to 3.64 mJ/cm². CAD-MOS also exhibits a reduced gate turn-on charge and demonstrates an enhancement in high-frequency figure of merit (HF-FOM) by 8.1%.