Adsorption and diffusion of gold adatoms on boron nitride nanoribbons: A first-principles study

We have carried out first-principles calculations to explore the adsorption and diffusion of Au adatoms on boron nitride nanoribbons (BNNRs). We found that Au adatoms prefer to locate at the edge B site of the ribbons for both armchair (A-) and zigzag (Z-) BNNRs. Different diffusion paths, such as diffusion from central region to edge site, along the subedge sites or along the edge sites, are considered. The unique atomic arrangement and electronic structures of Z-BNNRs make the Au adatom tend to migrate only to B edge site rather than to the both edges. Different from the cases of graphene nanoribbons, the energy barriers for A-BNNRs are higher than those of the corresponding paths for Z-BNNRs. The electronic structure calculations indicate the wide-band-gap features are preserved in the Au-doped BNNRs as the Au concentration is low. With the increase of Au concentration, the Au adatoms form an atomic chain along the B zigzag edge, resulting in band gap closure. These results are expected to provide useful information for the development of nanoscaled electronic devices based on BNNRs.