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.