Theoretical Study of Edge States in BC 2 N Nanoribbons with Zigzag Edges

Abstract Graphene is an atomically thin carbon sheet in which carbon atoms are arranged in a honeycomb lattice. Due to their outstanding electronic structure and electron transport properties, graphene attracts much interest for future electronic devices. Graphene nanoribbons are finite width graphene sheets. The electronic properties of graphene nanoribbons strongly depend on the edge structures On the other hand, boron and nitrogen atoms behave as acceptors and donors, respectively. Therefore, boron-carbon-nitride, i.e., graphene sheet doped with B and N, should show interesting electronic properties with controllability by doping. BC 2 N sheet is organic analogous of graphene, which can be regarded as one of example of boron-carbon-nitride. Graphite-like BC 2 N was synthesized using chemical vapor depositions of boron trichloride, BCl 3 , and acetronitrile, CH 3 CN In this paper, we investigate the electronic properties of BC 2 N nanoribbons with zigzag edges using a tight binding model. In the tight-binding model, B and N atoms are described by higher and lower site energy, E B and E N , compared with that of C atom, E C , respectively Figure 1 (b) shows calculated results of the band structures of BC 2 N nanoribbons for N = 10. We observed the flat bands at E = 0. However, we confirm that the flat bands are absent if atoms are not arranged as B-C-N-C along the zigzag lines. Therefore, we can conclude that B-C-N-C arrangement along the zigzag line is necessary to obtain the flat bands. In the right part of In the model-1, the charge distributions at the both edges are different each other, i.e., the charge distribution at the edge, where the outermost sites are occupied with C atoms, is similar to that at the conventional zigzag edge, while the charge of the edge states at the edge, where the outermost sites are occupied with B and N atoms, distributes the both sublattice sites. Recently, Kaneko et al. showed that the edge states in zigzag graphene nanoribbons are robust on the substitution of outermost C atoms with B and N atoms alternately In this paper, we also performed the first-principles calculations based on the density functional theories within projector-augmented wave method and the local density approximation implemented in VASP code. We shall discuss the comparison of the results within the tight-binding model with those within the density functional theories