Graphene/h-BN In-Plane Heterostructures: Stability and Electronic and Transport Properties

We present a first-principles study of structural, electronic, and transport properties of in-plane Gr:BN heterostructures in the form of graphene stripes embedded in a BN matrix. In our calculations, we consider carbon, nitrogen, and boron chemical potentials that are consistent with growth conditions (gas sources and temperatures) at either nitrogen-rich or boron-rich environments. Interestingly, we find that structures with excess of B atoms can be energetically more stable than structures with excess of N atoms even in N-rich growth conditions. The general trend is that N-rich growth conditions favor B/N stoichiometric heterostructures, while B-rich growth conditions favor heterostructures with excess of B atoms at the graphene/BN junctions, such that only B–C bonds occur at both edges of a graphene stripe region embedded in BN. We also investigate the dependence of magnetic properties and the band gap magnitudes of graphene stripe regions embedded in BN with several structural characteristics. We find that graphene stripes with only one bond type (either B–C or N–C) at the graphene/BN edges always present metallic behavior, with zigzag-oriented stripes of this type presenting large magnetic moments. Finally, we obtain the characteristic I–V curves for systems formed by junctions of two graphene stripes embedded in BN, one of them terminated by C–N bonds and the other terminated by C–B bonds. We find that systems of this type should present rectifying behavior.