Low-energy (~0.5MeV) electrons arising from 60Co γ-irradiation were used to create phosphorus–vacancy pairs and oxygen–vacancy pairs in Czochralski-grown Si. Positron annihilation data showed that the phosphorus–vacancy pairs annealed out in two stages: one was the commonly observed stage around 125C, where one third of the pairs disappeared with an activation energy of 0.8eV; the other was a new stage where none disappeared, but formed phosphorus–vacancy–oxygen complexes with an activation energy of 2.0eV.

Evidence for a Vacancy–Phosphorus–Oxygen Complex in Silicon. S.Dannefaer, G.Suppes, V.Avalos: Journal of Physics - Condensed Matter, 2009, 21[1], 015802