Electronic structure and transport properties of N₂ ^AA-doped armchair and zigzag graphene nanoribbons

Substitutional doping in graphene nanoribbons (GNRs) promises to enable specific tuning of their electronic properties. Recent work by Lv et al (2012 Nature Sci. Rep. 2 586) on large sheets of nitrogen-doped graphene determined that a highly predominant amount of nitrogen dopants (80%) are present in pairs of neighbouring atoms of the same sublattice A, denoted as N₂ ^AA dopants, following the notation of Lv et al. Here, we explore the electronic and transport properties of armchair (aGNR) and zigzag (zGNR) graphene nanoribbons under different orientations of the N₂ ^AA dopants with respect to the ribbon growth direction. For all dopant configurations of zGNRs and aGNRs, we find a substantial decrease in conductance, with new conductance gaps opening in some cases, and spatially localized states induced around the dopant sites. We also provide simulated scanning tunnelling microscopy images that will aid in the experimental identification of the presence of these structures in N-doped GNR samples.