NESTING OF C-60 AROUND AU CLUSTERS ON A C-60 CRYSTALLITE

Room temperature deposition of Au on a thin C-60,, film formed on a Si (lll) substrate has been studied with scanning tunneling microscopy. A u atoms adopt 3D clustering on the surface of a C-60,, crystallite. As the cluster grows bigger, its facets become binding sites that attrac t C-60,, molecules detached from step edges and diffusing on the surfa ce, resulting in a nested cluster structure with a lateral size of 30- 70 Angstrom. At an early stage common nested cluster configurations ar e found to be pentagonal and hexagonal, reflecting the size and shape of the core metal clusters. This nesting process plays the role of pas sivating the Au cluster during its growth and results in a self-limiti ng growth mode. The continuation of this process to higher Au coverage leads to a roughening of the C-60,, substrate. The self-limiting grow th process of the Au clusters by a capping C-60,, layer could potentia lly be used to fabricate C-60-passivated monodisperse metal clusters. (C) 1997 Elsevier Science B.V.