Evolution transients were measured in hydrogenated amorphous material which had been prepared by the Si implantation of crystalline Si, followed by H implantation. The evolution curves were found to be similar for various H concentrations, but were associated with entirely different atomic and nano-scale structures; as revealed by small-angle X-ray scattering and infra-red absorption data. The results were explained in terms of H diffusion-controlled effusion, with a limited density of available sites, in the amorphous material, for occupation by H. Diffusion through highly disordered material with a low H content was found to be governed by an activation energy of 2.26eV.

Effects of the Defect Structure on Hydrogen Transport in Amorphous Silicon. S.Acco, W.Beyer, E.E.Van Faassen, W.F.Van der Weg: Journal of Applied Physics, 1997, 82[6], 2862-8

Figure 6

Diffusivity of H in Si

D (cm2/s) = 2.485 x 101 exp[-1.27(eV)/kT]