Investigation of defect evolution in 4H-SiC epitaxial layers via scratch-etching method

Abstract To elucidate the mechanisms of material deformation and defect evolution in 4H-SiC epitaxial layer, this study proposes an innovative method named the scratch-etching method, to systematic investigate the defect evolution of 4H-SiC. To simulate the mechanical responses of the material under practical application conditions, nanoindentation and nano-scratch were conducted on the epitaxial layer. Subsequently, KOH etching was employed to reveal the structural characteristics of internal defects, such as dislocations and stacking faults. Detailed characterization of the electrical properties and crystal structure of different types of defects was performed. The results reveal that stress concentration is the main reason of defects in the 4H-SiC epitaxial process. In addition, the presence of threading mixed dislocation and threading screw dislocation may increase the leakage current in the 4H-SiC power devices.