Oxygen-vacancy complex in silicon. I.Si29electron-nuclear double resonance

The negative charge state of the oxygen-vacancy complex in silicon has been studied by electron-nuclear double resonance. Hyperfine interactions between the unpaired electron and ${}_{}{}^{29}{}_{}{}^{}\mathrm{Si}$ nuclei in 50 shells of neighboring lattice sites have been determined. These shells contain 145 lattice sites. From a linear combination of atomic orbitals analysis, it was deduced that the defect wave function was primarily localized on silicon atoms in a single 〈011〉 lattice chain that contains the vacant lattice site. The same preference for a one-dimensional extent of the wave function had already been observed in the single vacancy in silicon. As for the vacancy, a symmetry-forbidden plane of lattice sites is observed for the vacancy-oxygen complex as well. In addition to the hyperfine interactions that could be identified with lattice sites in the chain or in the forbidden plane, many more hyperfine interaction counterparts could be identified from the results for the vacancy. Since for a total of 66% of all interactions a correspondence between the oxygen-vacancy complex and the vacancy was found to exist, it is concluded that the electronic structures of both defects are highly similar.