Abstract
We present a study of the electronic properties of narrow zigzag and armchair nanoribbons substitutionally doped with a single boron, nitrogen, or phosphorus atom. Using density functional calculations, we analyze the formation energy, electronic band structures, magnetic, and quantum conductance properties of these nanoribbons with doping site positions ranging from the edge to the center of the ribbon. Substitutional doping is found to be most favorable at the ribbon edge in all the cases except for the boron-doped armchair ribbon, which has the lowest formation energy in the three-coordinated site next to the edge. Boron-doped zigzag nanoribbons exhibit spin-dependent donor-like states when the dopant is on the ribbon edge, and acceptor states as the dopant moves toward the ribbon center. Nitrogen doped zigzag nanoribbons show the opposite effect, while phosphorus doped nanoribbons exhibit both donor-like and acceptor-like states. The band structure and local density of states of these ribbons indicate that dips in conductance occur from either the presence of a localized state or the opening of mini band-gaps around a particular energy value. The variations in conductance arising from different doping profiles could be useful for tailoring the properties of graphene-based nanoelectronic devices.
