Hydrogen diffusion and densification in amorphous silicon

Hydrogenated amorphous silicon prepared by evaporation onto low-temperature substrates is characterized by a low-density network and by the presence of (${\mathrm{SiH}}_{2}$${)}_{\mathit{n}}$ bonds. By monitoring the decay of the small-angle neutron-scattering intensity during annealing of Si/Si:H/Si/Si:M/... (M=${\mathrm{H}}_{28}$${\mathrm{D}}_{72}$) multilayers, it is possible to follow simultaneously the densification of the silicon network and the diffusion of the hydrogen atoms.