Fracture mechanics and crack propagation of nanoscale silicon carbide via molecular dynamics simulation

Abstract

The fracture toughness, mechanical properties, and crack propagation behaviour of defective single-layer silicon carbide (SiC) nanosheets were investigated through a molecular dynamics (MD) study. Various types of defects were modelled to examine their mechanical properties and toughness under different temperatures. The results indicated that the mechanical properties of both defect-free and defective SiC diminished with increasing temperature and defect size. At room temperature, the failure stress of SiC decreased by approximately 47.22, 48.73, and 52.34 GPa for crack lengths of 25 Å, and circular and square notches with diameters of 25 Å, respectively. Similar trends were observed in Young’s modulus and failure strain. Additionally, higher stress concentrations at the corners suggested that samples with square defects had the weakest properties. As the crack size increased, the stress intensity factor of SiC also increased. Defects propagated in the direction perpendicular to the stress loading, and larger defect sizes mitigated the adverse effect of temperature on failure stress. This research is significant in analysing the mechanical behaviour of SiC, a key wide-bandgap semiconductor structure with substantial potential applications in advanced power devices.