C60 single crystal films on GaAs/InAs(001) surfaces

In this paper, we report a scanning tunnelling microscopy study of C60 thin film growth on the GaAs(001) As-rich 2 × 6 and InAs(001) In-rich 4 × 2 surfaces prepared by molecular beam epitaxy. On the 2 × 6-As surface, the corrugated potential of the 2 × 6 substrate forces the first monolayer structure to be strongly modified resulting in formation of a ‘double-chain’ commensurate structure. C60-substrate interaction, however, is limited to 2–3 monolayers at the interface and the competing intermolecular interaction governs the 3-dimensional growth of multiple-layer C60 FCC crystalline film on the InAs(001). In 4 × 2 surface, the C60 molecule is very mobile even at room temperature. The intermolecular interaction is significant and overcomes the substrate corrugated potential, and 2-dimensional islands with quasi-hexagonal close-packing form even at submonolayer coverage.