FIRST STAGE OF OXYGEN AGGREGATION IN SILICON - THE OXYGEN DIMER

The structure and dynamic properties of the interstitial oxygen dimer in silicon are found using a combination of infrared spectroscopy and ab initio modeling. We find that the stable dimer consists of a pair o f inequivalent weakly coupled interstitial oxygen atoms separated by a Si-Si bond. Two high frequency modes are decoupled in one O-16-O-18 c ombination but are strongly mixed in the other combination. A third lo wer lying mode involves the compression of the Si-Si bond joining the oxygen atoms and gives distinct modes in the mixed O-16-O-18 case.