Abstract: The subthreshold characteristics for SiC Buried-Channel MOSFETs were studied based on an equivalent channel thickness model.The expression of equivalent channel thickness was developed with the solution of Poisson's equation.The results show that the equivalent channel thickness is independent of gate voltage if N⁺_D/N^-_A≤43.The peak potential at subthreshold region varies with gate voltage linearly,and a simple expression of drain current in subthreshold region is obtained,in which the effect of interface state is included.The expression can be used to extract some important parameters.