Study of the Influence of Different Gate Oxide Traps on Threshold Voltage Drift of SiC MOSFET Based on Transient Current

With the aim of resolving the threshold voltage drift problem of the silicon carbide metal-oxide-semiconductor field-effect transistor (SiC mosfet), which is caused by traps, this article presents a study of the laws for the different traps that affect threshold voltage drift and also clarifies the details of the trap that leads to the SiC mosfet threshold voltage drift. First, based on use of the transient current method for trap characterization, we eliminate the interference from the SiC bulk traps, and the time constant spectrum of the gate oxide trap is then obtained accurately. Second, the effects of the different traps on the threshold voltage are studied by filling or releasing the charges from traps with different time constants. The main trap time constant that leads to the SiC mosfet threshold voltage drift is revealed to be 300 ms, whereas the other trap only affects the current and hardly contributes to the threshold voltage drift. Finally, based on the activation energies of the different traps, it is inferred that the trapping mechanism of the traps are the trap-assisted tunneling effect and the hot electron emission effect, and the corresponding trap types are identified as the oxide trap and the interface trap, respectively.