Silicene and Germanene: A First Principle Study of Electronic Structure and Effect of Hydrogenation-Passivation

Department of Physics, Maulana Azad National Institute of Technology (MANIT), Bhopal 462051, IndiaUsing first principle calculations we have explored the structural and electronic properties of silicene(silicon analogue of graphene) and germanene (germanium analogue of graphene). The structuraloptimization reveals that buckled silicene and germanene are more stable than their planar counter-parts by about 0.1 and 0.35 eV respectively. In comparison to planar graphene (buckling parameter =0 A) the germanium sheet is buckled by 0.737 A and silicene by 0.537 A but both have similarelectronic structure with zero band gap at K point as that of graphene. Further we investigated theeffects of complete hydrogenation on these materials by considering different geometrical config-urations (chair, boat, table and stirrup) and found that chair-like structure has the highest bindingenergy per atom in comparison to other structures. Hydrogenated silicene (silicane) shows an indi-rect band gap of 2.23 eV while hydrogenated germanene (germanane) possess a direct band gapof 1.8 eV.