High Resolution Observation of Subsurface Defects at SiO2/4H-SiC Interfaces by Local Deep Level Transient Spectroscopy Based on Time-Resolved Scanning Nonlinear Dielectric Microscopy

High resolution observation of density of interface states (Dit) at SiO
₂
/4H-SiC interfaces was performed by local deep level transient spectroscopy based on 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 nanometers, 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.