IDENTIFICATION OF THE MIGRATION PATH OF INTERSTITIAL CARBON IN SILICON

We have performed ab initio total-energy calculations of ground-state properties and migration paths of interstitial carbon in silicon. The ground state involves threefold-coordinated carbon and silicon atoms and its geometry suggests primarily p and sp bonding for carbon, rather than sp(2) one would naively expect. Examination of possible migration paths reveals that only three correspond to small ''jumps'' involving a single ''bond breaking.'' Of these, we predict that only one has a barrier of considerably lower energy (similar to 0.5 eV) and involves an intermediate ''saddle-point'' configuration of C-2 symmetry.