Synthesis of new silicene structure and its energy band properties

Silicene, silicon analogue to graphene possesses a two-dimensional (2D) hexagonal lattice, has attracted increasing attention in the last few years due to predicted unique properties. However, silicon naturally adopts the three-dimensional diamond structure, so there seem to be not any natural solid phase of silicon similar to graphite. Here we report the synthesis of new silicene structure with a unique rectangular lattice through using irradiation of coherent electron beam on amorphous silicon nanofilm produced by pulsed laser deposition (PLD). Under coherent electron beam irradiation with proper kinetic energy, the surface layer of silicon nanofilm can be crystallized into silicene. The dynamic stability and the energy band properties of this new silicene structure were investigated using first-principle calculations and density function theory (DFT) with the observed crystalline structure and lattice constant, which has a real direct bandgap of 0.78eV. It is interesting in the simulating calculation that the convex bond angle with 118° was measured in the new silicene structure with rectangular lattice. The DFT simulations reveal that this new silicene structure has a Dirac-cone like energy band. The experimental realization of silicene and the theoretically predicted properties shed a light to silicon material with potential new device applications.