H interacting with intrinsic defects in Si

B Bech Nielsen, L Hoffmann, M Budde, R Jones, J Goss and S Öberg
Materials Science Forum

The Si-H stretch modes of vacancy-hydrogen complexes are studied by infrared absorption spectroscopy, uniaxial stress measurements, and ab initio theory. Hydrogen and/or deuterium is introduced by ion implantation which facilitates studies of isotopic shifts. The Si-H mode at 2222 cm−1 is identified as the T2 mode of the fully saturated vacancy (VH4). Modes at 2166 and 2191 cm−1 are ascribed to VH3 and modes at 2121 and 2144 cm−1 to VH2. Another mode at 2068 cm−1 is tentatively assigned to VH0 and two modes at 1987 and 1990 cm−1 are tentatively ascribed to a <100>-split interstitial saturated by two hydrogen. The calculations show that all these complexes are stable and the calculated quasi-harmonic frequencies reproduce the trend in the observed frequencies, although the theoretical values are about 5% too high. The influence of anharmonicity upon these frequencies is also briefly discussed.

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