Energetics of bonded hydrogen for realistic a-Si : H supercells - art. no.165206

Using ab initio density functional calculations we investigate the energeti cs of hydrogen in a-Si:H starting from a basic supercell that contains 142 atoms and is completely free of defects. The study includes isolated H atom s bonded to dangling bonds, H atoms bonded to dangling bonds in regions of clustered H, and bond-centered hydrogen. In particular, the difference betw een clustered and isolated hydrogen has been largely ignored in the past. E nergetics of doped as well as undoped cells are considered. The results are discussed with particular emphasis on H diffusion.