Cluster calculations of hyperfine coupling constants, based upon density functional theory, were performed for the C <100> split interstitial (VC + 2C) in various charge and spin states in cubic SiC, together with the dihydrogen-containing defect (VC + 2H). When compared with the isolated C vacancy, the presence of two C atoms in the split interstitial center caused a lowering of the point symmetry, for positive and negative charge states, from D2d to D2 and substantially reduced the spin density on the nearest Si neighbours. A density functional theory-based approach was used for calculating the zero-field splitting parameters of the neutral (VC + 2C)0 state with spin S = 1. Singly-charged and neutral C <100> split interstitial defects were suggested as being a microscopic model of the well-known T5 (initially identified as being VC+ and then re-identified as being a dihydrogen-containing complex) and EI3 centers in SiC, respectively.

The Carbon <100> Split Interstitial in SiC. T.T.Petrenko, T.L.Petrenko, V.Y.Bratus: Journal of Physics - Condensed Matter, 2002, 14[47], 12433-40