Density functional theory study of BN-doped graphene superlattice: Role of geometrical shape and size

Effects of geometric shape and size of embedded boron nitride (BN) nanodot on the electronic and magnetic properties of the BN-doped graphene superlattices are systematically studied by spin-polarized first-principles calculations. The band gap of graphene superlattice is found to increase with the size of the BN nanodot, regardless of the shape of BN nanodot. Midgap states are found for graphene superlattices with triangular BN nanodots, and the number of such midgap states is determined by the imbalance between the number of carbon atoms occupying A- and B-sublattices, which is closely related to the geometric shape and size of the BN nanodot. When B and N atoms in the superlattices are exchanged, the valance bands and conduction bands are inverted with respect to the Fermi level due to electron-hole symmetry. Furthermore, partial occupation of the midgap states induces spin-polarization, and results in a magnetic ground state for the BN-doped graphene superlattices with triangular BN nanodots. Through electron or hole injection, the magnetic moment of the BN-doped graphene superlattice can be tuned, which may find applications in spintronic devices. (c) 2010 American Institute of Physics. [doi:10.1063/1.3487959]