Molecular pathways and thermal stabilities of vacancy-complex formation in silicon carbide

Electron spin defects in silicon carbide (SiC), in particular divacancies, are emerging platforms for hosting solid-state qubits for scalable quantum technologies. Despite successful electronic and optical characterizations of divacancies in SiC, it remains challenging to control their formation and, in general, to engineer defects with desired properties. Here we investigate the dynamics of several vacancy defects in SiC using molecular dynamics simulations. We find that Si and C monovacancies have differential stabilities giving rise to complex divacancy formation and dissociation pathways. We identify pathways along which new promising spin defect complexes (e.g., antisite-vacancy) are formed. The predicted temperature-dependent behavior of vacancy defects agrees well with recent annealing experiments. Our results show that the stability of silicon and the mobility of carbon monovacancies limit the formation of divacancies at high temperatures, providing molecular insights into the controlled generation of spin defects hosted in vacancy complexes.