Static Characteristics and Avalanche Robustness of SiC Mosfet with P-Well Surface Doping Investigation

This work investigates the effects of the surface doping concentration in the P-well region on the static characteristics, short-circuit (SC) reliability and single-pulse unclamped inductive switching (UIS) characteristics of commercial planar SiC MOSFETs gate structures. Simulation results show that increasing the surface doping concentration in the P-well region increases threshold voltage and on-resistance. With sufficient surface doping, the breakdown voltage remains unaffected. In contrast, channels with lower surface doping concentration may turn on without an applied gate voltage in a simulated industrial environment. SC simulation test results show that the peak SC current decreases with increasing doping concentration due to the channel's narrowing of the current path, resulting in a lower peak short-circuit current. The single-pulse UIS test results show that increasing the surface doping reduces the electron current during an avalanche and shortens the duration of the avalanche event, thereby improving the robustness of the device. This paper reveals the positive impact of a high P-well region surface doping concentration on the performance of SiC MOSFETs in multiple dimensions, providing a valuable reference for the industry in optimizing device design and process.