TCAD Modeling of Temperature Activation of the Hysteresis Characteristics of Lateral 4H-SiC MOSFETs

Abstract

We investigate the temperature dependence of the hysteresis in the transfer characteristics of 4H silicon carbide (4H-SiC) lateral MOSFETs. Within temperatures ranging from 150 to 300 K, we experimentally characterize the hysteresis width as the difference of the threshold voltage between up and down sweeps. We observe a considerable increase in the hysteresis width toward lower temperatures. When the gate voltage sweeps up, the threshold voltage shifts toward positive gate voltages. This shift is maintained even during the subsequent down sweep. We attribute this behavior to acceptor-like border traps, which get more negatively charged at higher gate voltages. These traps are presumably located near the SiC/SiO₂ interface with energy levels close to the SiC conduction band edge. Using a two-state non-radiative multi-phonon model, we calculated capture and emission times to show that the hysteresis width corresponds to the charge stored on these traps and, hence, possesses an intrinsic temperature dependence due to the transition barriers.