The substitutional B-vacancy BsV complex in Si was investigated using the local density functional theory. These theoretical results gave an explanation of the experimentally reported, well established metastability of the B-related defect observed in p-type Si irradiated at low temperature and of the two hole transitions that were observed to be associated with one of the configurations of the metastable defect. BsV was found to have several stable configurations, depending on charge state. In the positive charge state the second nearest neighbor configuration with C1 symmetry was almost degenerate with the second nearest neighbor configuration that had C1h symmetry since the bond reconstruction was weakened by the removal of electrons from the center. A third nearest neighbor configuration of BsV had the lowest energy in the negative charge state. An assignment of the three energy levels associated with BsV was made. The experimentally observed Ev+0.31eV and Ev+0.37eV levels were related to the donor levels of second nearest neighbor BsV with C1 and C1h symmetry respectively. The observed Ev+0.11eV level was assigned to the vertical donor level of the third nearest neighbor configuration. The B-divacancy complex BsV2 was also studied and was found to be stable with a binding energy between V2 and Bs of around 0.2eV. Its energy levels lie close to those of the V2. However, the defect was likely to be an important defect only in heavily doped material.

Theory of Boron-Vacancy Complexes in Silicon. J.Adey, R.Jones, D.W.Palmer, P.R.Briddon, S.Öberg: Physical Review B, 2005, 71[16], 165211 (6pp)