Fullerene on Nitrogen-Adsorbed Cu(001) Nanopatterned Surfaces: From Preferential Nucleation to Layer-by-Layer Growth

Abstract

Nitrogen (N)-adsorbed Cu(001)−c(2 × 2) nanopatterned surfaces are used as templates to guide the growth of low-dimensional C60 molecular nanostructures. At room temperature and during the initial stages of growth, C60 molecules preferentially adsorb on the bare Cu regions on a partially N-covered grid surface. Subsequently, a two-dimensional molecular nanomesh is formed at low (∼0.28 monatomic layer) C60 coverages. Further deposition leads to C60 growth on the c(2 × 2)−N surface until the first molecular layer is completed. For a N-saturated surface with trench structures, the <010> steps of these structures serve as initial anchoring sites for C60 growth. From there, the growth proceeds two-dimensionally until a single C60 layer is achieved due to island coalescence. In contrast, no nucleation site was observed when the <110> steps were predominant on the surface. At least up to 6 monatomic layers, the growth proceeds layer-by-layer (i.e., the overlayer morphologies are directed by the underlying substrate pattern). Four rotational domains are observed for the quasi-hexagonally close-packed C60 overlayer with a nearest-neighbor C60−C60 distance of 1.02 nm. It was found that the interaction between C60 and the c(2 × 2)−N surface is fairly weak, likely dominated by van der Waals forces, whereas the C60−Cu interface is chemisorbed. Site-specific electronic effects between these two regions can be resolved by STM even for thick films.