Point defects engineering in graphene/h-BN bilayer: A first principle study

Point defects engineering in a new type hetero bilayer consisting of graphene and hexagonal boron-nitrogen (h-BN) sheet, including vacancy, substitutional C/B/N doping and the possible combinations of the former two, was theoretically studied using first-principles calculations. The optimized geometry, formation energy, magnetic moment, and electronic property of these systems are discussed. It was found that N vacancy is more likely to form than B vacancy in graphene/h-BN bilayer and their electronic properties exhibit n-type and p-type conductivity, respectively. Divacancy of N and C in hetero bilayer shows high stability and induces direct band gap in up and down spin, respectively. Combined by N substitutional doping in graphene and B vacancy in h-BN layer, this substitution-vacancy combination shows low formation energy and changes the semiconductor property of pristine graphene/h-BN bilayer to metallic. In contrast, the graphene/h-BN bilayer with the combinated defect of C-substitution in B site and C vacancy in graphene shows half-metallic electronic property. The calculated magnetic moments are in reasonable agreement with the available theoretical analysis on atomic charge distribution. This work reveals that the electronic and magnetic properties of graphene/h-BN bilayer can be effectively tuned by above proposed point defects engineering.