Site-dependent defect formation and evolution in 4H-silicon carbide: A molecular dynamics study

Displacement cascades induced by ion implantation are a crucial process for fabricating color centers in 4H-silicon carbide, while the differences in defect formation and evolution at hexagonal and cubic lattice sites are often overlooked. In this study, molecular dynamics simulations were employed to systematically investigate the site-dependent formation and evolution of point defects and divacancies in 4H-silicon carbide. The results indicate that the stable number of displaced atoms at cubic sites is significantly higher than that at hexagonal sites, primarily driven by carbon displaced atoms, whereas vacancy concentrations show no substantial site difference. This behavior is attributed to the lower threshold displacement energy of cubic carbon atoms (∼30.19 eV) relative to hexagonal carbon atoms (∼33.31 eV), together with a site-exchange recombination process amplifying the displaced-atom disparity while narrowing the vacancy disparity. Moreover, the divacancies generated during the initial cascades are highly unstable, with approximately 80% undergoing recombination. Among the surviving stable divacancies, the production of basal configurations is significantly higher than that of axial configurations. This study provides critical data for developing site-resolved radiation damage models in 4H-SiC and offers valuable microscopic theoretical insights into the fabrication of solid-state quantum color centers via ion irradiation.