Simulation of Threshold Voltage Instability of 4H-SiC MOSFET

The reliability issue of threshold voltage (V gs ( th ) ) still exists in Silicon carbide (SiC) based metal-oxide-semiconductor-field-effect-transistors (MOSFETs). In this paper, the threshold voltage instability of 4H-SiC MOSFET is deeply studied through Silvaco TCAD simulation. This work mainly investigates the instability (shift) of the V gs ( th ) affected by interface states (interface traps), near interface traps, and mobile ions. The results display that the effect of near interface traps on the V gs ( th ) shift is greater than that of interface traps. The electron capture ability is related to the energy level of the traps. With the energy level increasing, the V gs ( th ) shift increases firstly and then decreases. The peak energy level is related to the trap position and trap density. Furthermore, the effect of the mobile ions in the oxide layer on the V gs ( th ) shift is limited. However, when moving to the SiC/SiO 2 interface, they will greatly impact the V gs ( th ) and affect the device performance seriously.