Surface Potential Fluctuations of SiO₂/SiC Interfaces Investigated by Local Capacitance-Voltage Profiling Based on Time-Resolved Scanning Nonlinear Dielectric Microscopy

Abstract

We investigate surface potential fluctuations on SiO2/SiC interfaces by local capacitance-voltage profiling based on time-resolved scanning nonlinear dielectric microscopy. As experimental indicators of surface potential fluctuations, we measured the spatial fluctuations of local capacitance-voltage and its first derivative profiles through the detection of the voltages at the infection points of the profiles. We show that, even for a sample with a nitrided interface with low interface defect density, the fluctuations of the measured voltages are much higher than the thermal energy at room temperature. This indicates the existence of high potential fluctuations, which can give the significant impacts on the carrier transport at the SiO2/SiC interface of SiC metal-oxide-semiconductor field effect transistors.