Growth of nanorods and mesoscale stars prior to an orientation transition in thin Bi films on graphite

We report on the growth of unusual star shaped Bi islands and ordered arrays of nanorods on highly ordered pyrolitic graphite (HOPG) substrates. The rods and stars grow with {0 1 2}Bi||{0 0 1}HOPG and are preferentially aligned with the high symmetry directions of the substrate. As more Bi is deposited, the film undergoes a transition to the {0 0 1} orientation. These features are a result of a complex interplay between kinetics, thermodynamics, and the crystallography of the substrate and island material.