A cluster calculation of hyperfine coupling constants based on density functional theory (DFT) has been performed for the carbon ⟨100⟩ split interstitial (VC + 2C) in various charge and spin states in cubic SiC along with the dihydrogen-containing defect (VC + 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 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 VC+ and then re-identified as a dihydrogen-containing complex) and EI3 centres in SiC, respectively.

Thermally grown SiO2 on Si substrates implanted with Si+ ions with a dose of 6×1016 cm−2 were studied by the techniques of photoluminescence, electron paramagnetic resonance (EPR), and low-frequency Raman scattering. Distinct oxygen-vacancy associated defects in SiO2 and nonbridging oxygen hole centers were identified by EPR. The luminescence intensity in the 620 nm range was found to correlate with the number of these defects. The low-frequency Raman scattering technique was used to estimate the average size of the Si nanocrystallites formed after the implantation and thermal annealing at T>1100 °C, which are responsible for the photoluminescence band with a maximum at 740 nm. The intensity of this band can be significantly enhanced by an additional treatment in a low-temperature rf plasma.

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