Migration, restructuring and dissociation energies of O complexes in Si were studied theoretically through density-functional total-energy calculations. It was found that the most stable O complexes were straight chains that also had the lowest migration energies. The calculated migration energies decreased from 2.3eV for an interstitial O atom, Oi, to values of 0.4 to 1.6eV for O2 to O9 chains and 1.9 to 2.2eV for longer chains. The O chains (which were thermal double donors) were expected to grow so that the migrating O chains captured less-mobile but abundant O atoms: On + Oi → On + 1. Restructuring energies of chains with a side Oi into straight O chains were 1.9–2.5eV. Restructuring gave an essential contribution to the fast diffusion. It was found that the shorter O2–O9 chains dissociate primarily by ejecting one of the outermost O atoms.

First-Principles Study of Migration, Restructuring and Dissociation Energies of Oxygen Complexes in Silicon. Y.J.Lee, J.von Boehm, M.Pesola, R.M.Nieminen: Physical Review B, 2002, 65[8], 085205