Phase field model of single Shockley stacking fault expansion in 4H-SiC PiN diode

Abstract

Expansion of a single Shockley stacking fault (SSF) during forward-current operation decreases the reliability of 4H-SiC bipolar devices. We propose a practical method for analyzing the defect evolution of SSF expansion based on free energy according to current density, temperature, and resolved shear stress conditions. The free energy includes chemical potential and elastic strain energy. Specifically, the chemical potential is related to the driving force for the formation of SSFs by temperature and current, and the elastic strain energy corresponds to the driving force for dislocations that form SSFs under the applied stress. It was confirmed that the proposed multiphysics method could well simulate SSF evolution when stress and current were applied. Furthermore, the results suggest that quantum well action, in which electrons in n-type 4H-SiC enter SSF-induced quantum well states to lower the energy of the dislocation system, affects the driving force of SSF formation.