Structures and electronic properties of silicene clusters: a promising material for FET and hydrogen storage

Structures and electronic properties of clusters of an all-Si analogue of graphene, silicene, have been studied through quantum chemical calculations. The structures of the six-membered rings show interesting chair like puckering, which for large sheet-like clusters form ordered ripples. Binding energies, HOMO-LUMO gaps and polarizabilities for the silicene clusters show interesting monotonic trends analogous to polyacenes. Stacking of two silicene layers leads to the formation of closed 3D clusters with high symmetry and strong Si-Si bonds. The heat of hydrogenation of silicene to form silicanes is overwhelmingly exothermic and leads to the opening up of the HOMO-LUMO gaps. Thus, analogous to graphanes, silicanes are predicted to be interesting materials for hydrogen storage and for their band engineering properties.