The Si-H stretch modes of vacancy-H complexes were studied by means of infra-red absorption spectroscopy, uniaxial stress measurements, and  ab initio  theory. The H and/or D was introduced by ion implantation, which facilitated the study of isotopic shifts. The Si-H mode at 2222/cm was identified as being the T2 mode of the fully saturated vacancy, VH4. Modes at 2166 and 2191/cm were attributed to VH3, and modes at 2121 and 2144/cm were attributed to VH2. Another mode, at 2068/cm, was tentatively attributed to VH0, and 2 modes at 1987 and 1990/cm were tentatively attributed to a <100>-split interstitial which was saturated by two H atoms. The calculations showed that all of these complexes were stable, and the calculated quasi-harmonic frequencies reproduced the observed trend in frequencies; although the theoretical values were about 5% too high.

B.B.Nielsen, L.Hoffmann, M.Budde, R.Jones, J.Goss, S.Oberg: Materials Science Forum, 1995, 196-201, 933-8