Comparative study of hydrogen stability in hydrogenated amorphous and crystalline silicon

The dependence of hydrogen effusion and diffusion on hydrogen concentration was studied for crystalline and amorphous Si:H samples which were hydrogenated by hydrogen ion implantation. The results are compared to data for a-Si:H and μc-Si:H films grown with various H concentrations. Although general trends of the H concentration dependence of H stability are similar, there are differences between c-Si:H and a-Si:H. These differences involve larger hydrogen-generated microstructural effects in c-Si:H and a hydrogen diffusion coefficient in compact material increasing in a-Si:H and decreasing in c-Si:H with increasing H concentration. A different flexibility of the atomic network in amorphous and crystalline Si could be the origin. Microcrystalline Si:H films show a similar concentration dependence of H diffusion as a-Si:H.