▎ 摘　　要

The electronic properties of two-dimensional hexagonal silicon (silicene) are investigated using first-principles simulations. Though silicene is predicted to be a gapless semiconductor, due to the sp(2)-hybridization of its atomic orbitals, the weak overlapping between 3p(z) orbitals of neighbor Si atoms leads to a very reactive surface, resulting in a more energetically stable semiconducting surface upon the adsorption of foreign chemical species. It is predicted that silicene inserted into a graphitelike lattice, like ultrathin AlN stacks, preserves its sp(2)-hydridization, and hence its graphenelike electronic properties. (c) 2010 American Institute of Physics. [doi:10.1063/1.3489937]