AFM study of surface phenomena based on C60 film growth

The surface phenomena of C-60 films were investigated using atomic force microscopy (AFM). The films were grown epitaxially on cleaved KBr (001) substrates under various conditions. For thin films (< 50 nm), single crystalline C-60 islands oriented randomly on the substrate due to the lattice mismatch between C-60 and substrate. Peculiar features were observed on the thin films, i.e., concave top surface, fivefold twinning and screw dislocation of the islands. The thick films (> 500 nm) showed different surface phenomena from the thin films. One of these is the spiral growth originated in screw dislocation. We observed both single and double spirals. Another is the surface reconstruction on the thick films. Furthermore, deposition-rate-dependence studies revealed that morphological changes from the (001) faces to the (111) faces depend on an increase in the deposition rates. (C) 1998 Elsevier Science B.V. All rights reserved.