It was demonstrated that, in high-quality hydrogenated amorphous films, almost 40% of the H content was in the form of H molecules which were individually trapped in the amorphous equivalent of tetragonal T-sites. The majority of these molecular H entities were in the less-clustered component of the H content. The results were suggested to have major implications for the understanding of light-induced defects and H mobility.

Molecular Hydrogen in a-Si:H. P.A.Fedders, D.J.Leopold, P.H.Chan, R.Borzi, R.E.Norberg: Physical Review Letters, 2000, 85[2], 401-3