Numerical analysis of the dislocation density in n-type 4H-SiC

Abstract

A 4H-SiC single crystal is a substrate material for high-frequency and high-voltage power devices. Dislocation density is a fundamental criterion for evaluating the quality of 4H-SiC single crystals. 4H-SiC single crystals grown by the physical vapor transport (PVT) method generally have high dislocation density. To investigate the effect of nitrogen doping on dislocation proliferation in SiC crystals, the thermal field of the ingot during PVT growth was calculated by COMSOL Multiphysics, and thermal stress was calculated by thermal elastic theory. Finally, the dislocation density of the crystal was calculated based on the Alexander–Haasen model for inhomogeneous nitrogen doping. By comparing the calculation and experimental results, we proposed a possible value of the effective stress to evaluate the effect of a nitrogen dopant on dislocation density, which helps calculate the dislocation density in the n-type SiC.