It was found that H existed in a molecular form in crystalline samples which were treated with H atoms in the downstream of a H plasma. The vibrational Raman line of H molecules was observed at 4158/cm, for samples which had been hydrogenated at temperatures between 180 and 500C. The attribution of the Raman line was confirmed by its isotope shift to 2990/cm, for material which was treated with D atoms. The Raman intensity went through a maximum, for hydrogenation at 400C. The vibrational Raman line of the H molecules was broad and asymmetrical. It consisted of at least 2 components, which may have arisen from H molecules in various occupation sites in crystalline material. A component at about 4160/cm was attributed to H2 in the tetrahedral interstitial site in crystalline material, as predicted by theoretical calculations. A component at about 4130/cm was tentatively attributed to H2, in the Td site, having a Si-H bond as its nearest neighbor. The rotational Raman line of H molecules was observed at 590/cm. The Raman band for Si-H stretching was observed for hydrogenation temperatures of between 100 and 500C, and the intensity exhibited a maximum for hydrogenation at 250C. The formation efficiency of H molecules was similar for samples with or without P+ implantation. A Raman peak at 2130/cm, which was observed in samples treated with H atoms at substrate temperatures of between 150 and 250C, was attributed to Si-H in {111} platelets.

N.Fukata, S.Sasaki, K.Murakami, K.Ishioka, K.G.Nakamura, M.Kitajima, S.Fujimura, J.Kikuchi, H.Haneda: Physical Review B, 1997, 56[11], 6642-7