Oxygen-Carbon, Oxygen-Nitrogen and Oxygen-Dimer Defects in Silicon

Abstract

An ab initio local density functional cluster method, AIMPRO, is used to examine a variety of oxygen related point defects in silicon. In particular results are given for X-O n complexes where X is interstitial C, N or O. For n = 2, the first defect, C-O2 has been assigned to the P-centre giving a PL line at 0.767 eV and seen in Cz-Si annealed around 450°C. The second, N-O2, has properties consistent with a nitrogen related shallow thermal donor. We have also found that a (C-H)02i defect has very similar electronic properties, and this implies that shallow thermal donors do not have a unique composition. The structure and migration energy of the oxygen dimer is considered and the dimer is found to migrate very much faster than a single oxygen atom.