A field-enhanced diffusion model was proposed for the observed phenomenon of dopant migration within 4H–SiC during high-temperature annealing. The proposed field-enhanced diffusion model was based upon the combined effects of both dopant diffusion and the in-built p–n junction electric field gradients found within the doped substrate resulting from the presence of the substrate dopants. Measured as-implanted dopant concentration profile data prior to high temperature annealing were utilized as input data for the proposed field-enhanced diffusion model. The resultant field-enhanced diffusion profile predictions of the proposed model during annealing were shown to be in excellent agreement with experimental findings. Parameters were extracted by using the field-enhanced diffusion model simulation for the high temperature ionic diffusivity and ionic field mobility for N dopant in B co-doped 4H–SiC. The extracted values for the ionic diffusivity and the ionic mobility of the N donor in B co-doped 4H–SiC found by using the model were 7.2 x 10–15cm2/s and 1.6 x 10–13cm2/Vs, respectively.

Field-Enhanced Diffusion of Nitrogen and Boron in 4H–Silicon Carbide. G.J.Phelps, E.G.Chester, C.M.Johnson, N.G.Wright: Journal of Applied Physics, 2003, 94[7], 4285-90