Nanoindentation insights into intrinsic fracture toughness anisotropy of SiC single crystals and implications for laser-guided fracture propagation

Abstract The manufacturability of silicon carbide (SiC) wafers is fundamentally constrained by how cracks nucleate and evolve within a crystallographically anisotropic lattice. In this study, orientation-controlled nanoindentation was used to investigate the fracture toughness anisotropy of single-crystal 4H-SiC along the <11 ̅00> and <112 ̅0> directions on both Si- and C-terminated basal surfaces. The measured fracture toughness ranges from 3.15 to 3.64 MPa·m½ and exhibits clear dependence on crystallographic orientation and surface polarity. Crack propagation along <11 ̅00> shows lower resistance and predominantly linear cleavage, whereas the <112 ̅0> direction promotes crack deflection and branching. The Si-terminated surface consistently shows slightly higher fracture resistance than the C face. These results demonstrate that intrinsic fracture anisotropy governs crack evolution in 4H-SiC and provides a quantitative basis for optimizing scanning direction and energy input in laser slicing processes.