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 (VC +2 C) in various charge and spin states in cubic SiC along with the dihydrogen-containing defect (VC +2 H). 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 D2d to D2 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 (VC +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 + and then re-identified as a dihydrogen-containing complex) and EI3 centres in SiC, respectively.