Effects of quantum confinement on interface trap occupation in 4H-SiC MOSFETs

SiC MOSFETs suffer from an excessively high density of interface traps. Here, we present physical models to quantify the effect of quantum confinement in the channel of 4H-SiC MOSFETs on the occupation of interface traps. Quantum confinement in the MOSFET channel is solved for using the density gradient approach. Models for estimating the Fermi level at the interface, and thereby evaluating the occupation probability of interface traps are presented in the quantum confined scenario, and the results are compared to classical models. Significant difference is observed in trap occupation, especially at large gate biases, between the classical and quantum cases. This argues for the need for accurate modeling of confinement effects on interface trap occupation in 4H-SiC MOSFETs.