The vibrational properties of interstitial SiH4 and SiH3 molecules in crystalline samples were calculated by using a first-principles cluster-based spin-polarized local-density method. The Si-H stretching modes were found to be red-shifted, by about 300/cm, with respect to those for the isolated molecule (at about 2200/cm). These results contradicted previous suggestions that the modes which were observed around 2200/cm, and which had been previously attributed to hydrogenated vacancy defects, were due to these interstitial molecules.

Self-Interstitial-Hydrogen Complexes in Silicon B.Hourahine, R.Jones, S.Oberg, P.R.Briddon: Physical Review B, 1999, 59[24], 15729-32