First-principles studies of the hydrogenation effects in silicene sheets

Using density functional theory (DFT) with both the generalized gradient approximation (GGA) and hybrid functionals, we have investigated the structural, electronic and magnetic properties of a two-dimensional hydrogenated silicon-based material. The compounds, i.e. silicene, full- and half-hydrogenated silicene, are studied and their properties are compared. Our results suggest that silicene is a gapless semimetal. The coverage and arrangement of the absorbed hydrogen atoms on silicene influence significantly the characteristics of the resulting band structures, such as the direct/indirect band gaps or metallic/semiconducting features. Moreover, it is interesting to see that half-hydrogenated silicene with chair-like structure is shown to be a ferromagnetic semiconductor.