NUCLEATION, GROWTH, AND STRUCTURE OF FULLERENE FILMS ON AU(111)

The growth of fullerene films by vapor deposition on Au(111) was studied using UHV-STM, LEED, AES, and TOF-SIMS. The fullerenes were found to grow in a layer-by-layer manner. The molecules initially adsorb at intersections of multiple steps and edges of monatomic steps on narrow terraces. As the coverage is increased, periodic arrays of short chains form at steps separating wider terraces with the periodicity determined by the (23 x square-root 3)-Au(111) reconstruction. At higher coverages, hexagonal layers with a lattice constant of 1.0 nm grow out from the steps on both the upper and lower terraces. The adsorption of the fullerenes lifts the reconstruction indicating a strong interaction between the fullerenes and Au(111). STM indicates that two ordered commensurate structures predominate on the Au(111) surface: (1) a layer with a periodicity of approximately 38 Au spacings; and (2) a layer with a (2 square-root 3 x 2 square-root 3)R30-degrees unit cell. Second layer molecules were found to display no affinity for step edges. On Au(111), the second layer desorbs at 300-degrees-C, while the first layer is strongly bound and does not begin to desorb until 500-degrees-C. After annealing to 500-degrees-C the remaining C60 is largely disordered. Intramolecular structure was observed within molecules at the step edges and in the hexagonal arrays.