Growth of oriented Bi nanorods at graphite step-edges

We report on the growth of ordered arrays of bismuth nanorods, extending outward from highly oriented pyrolitic-graphite (HOPG) step-edges. The rods grow via adatom diffusion in a multilayer two-dimensional growth mode, with {0112}Bi planes parallel to the basal plane of the substrate, and in-plane orientations aligned with the high symmetry directions of the substrate such that <1120>Bi parallel <1010>HOPG. The morphologies are characterized with varying particle flux and coverage. It is shown that bismuth aggregates become elongated when the particle flux is reduced. When coupled with an anisotropic diffusion field surrounding step-edge structures, this results in the manifestation of rods in a low flux growth environment. The rods are only ∼2 nm tall and can extend up to several microns in length