Signature of intrinsic defects in SiC: Ab initio calculations of hyperfine tensors

To reveal the microscopic origin of the spin-resonance centers in 3C- and 4H-SiC, we perform first-principles calculations of the hyperfine tensors for vacancy-related defects and interstitials. The calculations for the silicon vacancy corroborates the earlier experimental identification. The signature of the carbon vacancy in 4H-SiC, in contrast to the silicon vacancy, is found to discriminate between cubic and hexagonal sites. The EI5 center in 4H-SiC can be attributed to a carbon vacancy at the cubic site. The assignment of the $T5\mathrm{}$ center in 3C-SiC to a carbon vacancy or a complex of a carbon vacancy with hydrogen is not supported. The EI6 center in 4H-SiC originally identified as a silicon antisite is not compatible with the HF signature of this defect.