Morphological phase diagrams of C60 and C70 films on graphite.

The morphologies of C 60 and C 70 fullerene films vacuum-deposited onto graphite at various deposition rates and grown at several temperatures were investigated using atomic force microscopy. These fullerene films on graphite are model systems of physisorption of organic molecules that likely exhibit little chemical interaction with the graphite's surface. The morphologies of C 60 and C 70 films grown on graphite can be understood well from growth models previously reported. Comparison of the morphological phase diagrams obtained for C 60 and C 70 indicate that the diffusion properties of the adsorbed molecule are key in determining the morphology of the obtained film. The low diffusion rate of C 70 resulted in various film morphologies for all deposition conditions tested. Also, the obtained phase diagrams can be understood by the results of fractal dimension analysis on the C 60 and C 70 islands. The fundamental understanding of film growth obtained using these ideal physisorption systems will aid in understanding film growth by other molecular adsorption systems. [ABSTRACT FROM AUTHOR]