The tracer diffusion of D in hydrogenated amorphous material was studied by annealing sandwich structures of hydrogenated and deuterated material. The profiles could be fitted closely by analytical solutions which were based upon a trap-controlled diffusion model. It was found that, for annealing times which were shorter than the deep-H release time, the D profiles followed the as-grown profiles, except for the appearance of exponential wings at low concentrations. The wing amplitude increased almost linearly with time. In the long term, the solutions were identical to those for the trap-free case, but with an effective diffusion coefficient that could be calculated from features of the short-term tracer profiles. Various parameters of H diffusion were measured, including the H release time from deep traps and the mean displacement of free H before re-trapping.

H.M.Branz, S.Asher, B.P.Nelson, M.Kemp: Journal of Non-Crystalline Solids, 1993, 164-166[1], 269-72