IR studies of oxygen–vacancy defects in electron-irradiated Ge-doped Si

Abstract

The thermal evolution of multioxygen–vacancy (VO n ) centers produced in electron-irradiated Czochralski-grown Ge-doped Si was studied by means of IR spectroscopy. Two groups of samples with low [Ge]⩽1×10 17 cm −3 and high [Ge]=2×10 20 cm −3 were used. We found that the annealing temperature of vacancy–oxygen complexes (A-centers) produced in the course of irradiation at room temperature is substantially decreased in the samples with high [Ge]. This effect is explained taking into account an influence of the elastic stresses due to Ge atoms in the Si lattice on the migration barrier of A-centers as well as the rate of oxygen-related reactions, i.e. VO+O i→VO 2, VO+Si I→O i, etc. We also found that the ratio of A-centers converted to VO 2 defects is smaller in the material with high [Ge]. The same is also true for the conversion reaction VO 2+O i→VO 3. Contrary, the next reaction VO 3+O i→VO 4 shows a markedly enhanced rate if the Ge content is high. This observation can be explained considering the effects of Ge-induced stresses in the Si lattice on the successive trapping of oxygen atoms by A-centers and other VO n complexes as well as on the enhanced diffusivity of oxygen.