Understanding the Inversion-Layer Properties of the 4H-SiC/SiO2 Interface

The performance of 4H-SiC power MOSFETs is limited by the less than ideal electron inversion-layer mobility due to the poor quality of the SiC-SiO2 interface. This poor interface causes several undesirable behaviors of the electrical performance of SiC MOSFETs, including: (1) strong shifts in the threshold voltage with temperature, (2) low channel mobility and (3) strong sensitivity of the mobility to the channel doping concentration. These features are explained by a high density of interface states, the high surface electric field induced in SiC inversion layers, and the combined effectsa combination of Coulomb and surface roughness scattering.