Crystallographic Anisotropy in Vickers Hardness and Fracture Toughness of 4H‐SiC Single Crystals

ABSTRACT

4H‐Silicon carbide (4H‐SiC) is an excellent wide bandgap semiconductor material, playing an irreplaceable role in high‐power and high‐temperature electronic applications. Despite its superior physical properties, the extremely high hardness and inherent brittleness of 4H‐SiC would impose significant challenges to the fabrication of high‐quality wafers, particularly during machining processes such as grinding and polishing, where it easily induces subsurface damage. This study systematically investigated the mechanical anisotropy of 4H‐SiC single crystals, focusing specifically on the {0001}, , and planes. Through a series of Vickers indentation tests conducted at room temperature, this study quantified the orientation‐dependent hardness and fracture behavior. Experimental results show that the Vickers hardness ( H ) exhibits significant anisotropy, with the {0001} plane showing the highest hardness value, followed by and finally . Furthermore, analysis of radial cracks revealed a clear hierarchy of fracture resistance. Fracture toughness ( K _c ) also exhibits apparent anisotropy, with the order {0001} > > , reflecting the differences in surface energy and atomic bonding density among different crystal planes. The quantitative correlation between crystal orientation and crack length provides a predictive tool for evaluating material removal modes. These findings provide crucial theoretical support for optimizing the machining processes of SiC wafers, indicating that aligning the machining direction with specific crystal axes can minimize surface defects.