The carbon ⟨100⟩ split interstitial in SiC

A cluster calculation of hyperfine coupling constants based on density functional theory (DFT) has been performed for the carbon (100) split interstitial (V-C + 2C) in various charge and spin states in cubic SiC along with the dihydrogen-containing defect (V-C + 2H). Compared to the isolated carbon vacancy, the presence of two carbon atoms in the split interstitial centre causes lowering of the point symmetry for positive and negative charge states from D-2d to D-2 and substantially reduces the spin density on the nearest Si neighbours. The DFT-based approach has been used for a calculation of the zero-field splitting parameters D and E of the neutral (V-C + 2C)(0) state with spin S = 1. Singly charged and neutral carbon (100) split interstitial defects are suggested as a microscopic model of the well-known T5 (initially identified as V-C(+) and then re-identified as a dihydrogen-containing complex) and E13 centres in SiC, respectively.