B and N doping in graphene ruled by grain boundary defects

The energetics and electronic properties of substitutional B (BC) and N (NC) doping, and BN codoping in graphene with distinct grain boundary defects were investigated by ab initio simulations. Our results indicate that a single B or N impurity atoms and an isolated BN pair prefer to incorporate into the grain boundary region. In particular, we find that the formation of NC along the grain boundary sites is an exothermic process. It suggests that hexagonal-BN (h-BN) or h-BN and carbon (h-BNC) domains may be patterned by these defective regions. The electronic properties of those doped grain boundary systems have been examined through scanning tunneling microscopy (STM) simulations and electronic band-structure calculations. We find a quite different STM picture for the BC- and NC-doped grain boundaries when compared with the same impurities on the perfect graphene sheet.