Effect of Threshold Voltage Hysteresis on Switching Characteristics of Silicon Carbide MOSFETs

Threshold voltage ( {V}_{\text {TH}} ) hysteresis affects the reliability of silicon carbide (SiC) MOSFETs. To evaluate the {V}_{\text {TH}} hysteresis effect on switching characteristics, this article first investigates the {V}_{\text {TH}} hysteresis in the static characteristics of three SiC MOSFETs with different gate structures. The results illustrate the density of the interface states in different gate structures. Then, the effect of {V}_{\text {TH}} hysteresis on dynamic characteristics under varying OFF-state starting voltages ( {V}_{\text {G}}^{ \mathrm{\scriptscriptstyle OFF}} ) is evaluated by experiment. Furthermore, the effect mechanism of {V}_{\text {TH}} hysteresis and {V}_{\text {G}}^{ \mathrm{\scriptscriptstyle OFF}} on switching characteristics is analyzed. Under the effect of the {V}_{\text {TH}} hysteresis, a smaller {V}_{\text {G}}^{ \mathrm{\scriptscriptstyle OFF}} reduces {V}_{\text {TH}} when the device turns on. This phenomenon leads to a reduction in the turn-on delay and consequently lowers the turn-on loss. Therefore, the {V}_{\text {TH}} hysteresis is a significant factor for gate driver design of SiC MOSFETs.