The highly ordered epitaxial growth of C 60 films on rubrene single crystals was demonstrated. The C 60 crystals growth commensurate with rubrene (001) surface lattice was confirmed by reflection high energy electron diffraction and X-ray diffraction and grazing incident wide-angle X-ray scattering. Depending on growth conditions, several surface morphologies (rounded, hexagonal, and triangular grains) of C 60 grains were observed at the initial growth process. Large grains with layer-bylayer step and terrace structure of C 60 were observed at the terrace region of rubrene (001) surface. The growth of highcrystallinity C 60 films was achieved at high substrate temperature and slow deposition rate. Long migration length on the substrate which was given by enough substrate temperature enabled the formation of large single crystalline domains.

We have developed a method for epitaxial growth of C60 thin films on tetracene single crystals. The crystal orientation of the C60 film was examined by reflection high energy electron diffraction (RHEED) and X-ray diffraction (XRD). In-situ observation by RHEED revealed that the C60 crystallizes from the very initial stage of the deposition (0.1 nm). A 6-fold symmetric pattern, which was observed in a XRD polar scan, can be taken as direct evidence for the epitaxial growth of C60 commensurate with the tetracene (001) surface lattice.

not Available.