Spatial scale dependent impact of non-uniform interface defect distribution on field effect mobility in SiC MOSFETs

Understanding the properties of SiO₂/SiC interfaces is one of the key issues related to the development of SiC power devices. However, existing evaluation methods such as capacitance-voltage measurements do not directly provide microscopic assessments. Recently, the nanoscale imaging of interface defect density distributions has become possible using local deep level transient spectroscopy. This technique has shown that the defect density at a SiO₂/SiC interface can have a non-uniform, clustered distribution. Prior numerical simulations by our group have also demonstrated that this inhomogeneous clustering of interface defects may reduce field effect mobility in SiC metal oxide field effect transistors. The present work examines the relationship between the spatial scale of the non-uniformity and reductions in field effect mobility and shows that an interface defect distribution containing smaller features will have a greater effect on field effect mobility.