The infra-red spectra from Czochralski material in H2, D2 or their mixtures, at temperatures ranging from 1100 to 1300C, exhibited vibrational absorption at 1075/cm. This was attributed to perturbed bond-centered interstitial O atoms. Deconvolution of these absorption profiles implied that observed perturbations of the Oi were due to adjacent defects which incorporated two H atoms. This interpretation was confirmed by the detection of modes with 3789 and 3731/cm. The strength of both were related to that of the 1075/cm absorption. A third set of modes, at 3618/cm, was detected in heat-treated Czochralski and float-zone material, and was not related to the absorption at 1075/cm. It was instead attributed to H-H pair defects that were trapped at an unknown impurity or lattice defect. The frequencies of the various modes implied that the 3 defects were H2 molecules, with weakened bonds and small dipole moments, that resulted from interactions with adjacent O atoms or from a second type of trap. Annealing results implied that isolated Oi-H2 complexes could dissociate at temperatures greater than 70C; thus permitting interstitial H2 molecules to diffuse away. These could be re-trapped during subsequent annealing at temperatures below 50C.

R.E.Pritchard, M.J.Ashwin, J.H.Tucker, R.C.Newman, E.C.Lightowlers, M.J.Binns, S.A.McQuaid, R.Falster: Physical Review B, 1997, 56[20], 13118-25