High resolution observation of defects at SiO₂/4H-SiC interfaces using time-resolved scanning nonlinear dielectric microscopy

High resolution observation of density of interface states (D_it) at SiO₂/4H-SiC interfaces was performed by time-resolved scanning nonlinear dielectric microscopy (tr-SNDM). The sizes of the non-uniform contrasts observed in the map of D_it were in the order of several tens of nanometres, which are smaller than the value reported in the previous study (>100 nm). The simulation of the tr-SNDM measurement suggested that the spatial resolution of tr-SNDM is down to the tip radius of the cantilever used for the measurement and can be smaller than the lateral spread of the depletion layer width.