Structure and morphology of sexiphenyl thin films grown on aluminium (1 1 1) (original) (raw)

The epitaxial growth of sexiphenyl (C 36 H 26 ) on an atomically clean aluminium (1 1 1) surface is studied on the basis of thin films grown at different substrate temperatures. Thin films with an average thickness of 350 A are investigated by X-ray diffraction techniques and atomic force microscopy. Grown at room temperature the films show epitaxial order. It is found that the aromatic planes of sexiphenyl are oriented parallel to Al(1 1 1) and the long axes of the sexiphenyl molecules are aligned along a AE1 )1 0ae azimuthal direction at the Al(1 1 1) surface. The films grow in islands with average lateral dimensions up to of 200 nm and to 50 nm in height, the areas between the islands are observed as rather flat. The films grown at 150°C show a completely different morphology: occasional large islands and irregularly distributed segmented needles with a relatively constant width of about 0.5 lm, lengths up to 100 lm and heights of about 600 nm.