Formation and annealing of nitrogen-related complexes in SiC

We propose a mechanism for the annealing of vacancy-related defects in SiC, based on ab initio total energy calculations. Our mechanism is based on the formation and migration of carbon and nitrogen split interstitials resulting in CSi(NC)ₙ or VSi(NC)ₙ complexes as intermediate annealing products: In as-implanted samples, only recombination of nearby defects is possible, e.g., the disappearance of divacancies can be explained by a formation of VSiNC pairs $(P12$ centers). Dissociation of these very stable pairs at temperatures below 2000^∘C is not possible. At elevated temperatures above 1000^∘C, further aggregation becomes possible, resulting in electrically and optically inactive VSi(NC)₄ complexes. The recombination with carbon split interstitials, resulting in CSiNC and CSi(NC)₂ donors, are discussed as competing processes.