The interstitial C-O defect was a prominent defect formed in electron-irradiated Czochralski Si containing C. Previous stress alignment investigations have shown that the O atom weakly perturbed the C interstitial but the lack of a high-frequency O mode was taken to imply that the O atom was severely affected and became over-coordinated. Local

vibrational mode spectroscopy and ab initio modeling were used to investigate the defect. New modes were found whose O isotopic shifts furnished further evidence for O over-coordination. Moreover, it was found that the calculated stress-energy tensor and energy levels were in good agreement with experimental values. The complexes formed by adding both single (CiOiH) and a pair of H atoms (CiOiH2), as well as the addition of a second O atom, were considered theoretically. It was shown that the first was bistable with a shallow donor and deep acceptor level, while the second was passive. The properties of CiOiH and CiO2iH were strikingly similar to the first two members of a family of shallow thermal donors that contain H.

Interstitial Carbon-Oxygen Center and Hydrogen Related Shallow Thermal Donors in Si. J.Coutinho, R.Jones, P.R.Briddon, S.Öberg, L.I.Murin, V.P.Markevich, J.L.Lindström: Physical Review B, 2002, 65[1], 014109 (11pp)