Non-monotonic threshold voltage variation in 4H-SiC metal–oxide–semiconductor field-effect transistor: Investigation and modeling

We propose an analytical model to reproduce the non-monotonic instability of threshold voltage in 4H-SiC MOSFETs submitted a positive gate stress bias. Experimental analysis transients indicates that both electron and hole trappings take place dielectric or at dielectric/semiconductor interface, responsible for VTH increasing–decreasing–increasing pattern. At low/moderate fields (<7 MV/cm), trapping kinetics shift are modeled by rate equation considering trapping-inhibition model, which explains logarithmic degradation kinetics. In high field regime (>8 we electrons can tunnel through SiO2, be accelerated field, generate holes impact ionization (II) anode injection. These then trapped oxide, thus generating negative shift. This second process has exponential time-dependency, as found corresponding equations. The time constant is evaluated function temperature. results indicate strongly dependent on electric (that accelerates holes), not thermally activated, agreement with theoretical considerations.