A diffusion-reaction model was proposed for H diffusion in amorphous and crystalline samples. According to this model, molecular H dissolved and diffused interstitially in the open Si structure. Dissolved molecular H reacted with Si to form SiH groups. Equations which were derived for this model gave profiles that fitted well the experimental H profiles for amorphous Si. Other experimental features, such as steps in the H and D concentrations at interfaces, short-term exponential profiles and a decrease in the effective diffusion coefficient with increasing time, all arose naturally from the diffusion-reaction model.

Diffusion of Hydrogen in Silicon: Diffusion-Reaction Model. R.H.Doremus: Materials Research Innovations, 2000, 4[1], 49-59