Quaterphenyl thin films were grown on Au(111) surfaces which were intentionally covered by different amounts of carbon. The films were investigated by X-ray diffraction and atomic force microscopy. An epitaxial character of the quaterphenyl crystallites could be confirmed for films grown on a clean Au(111) surface, with the (211) plane of quaterphenyl parallel to the An(111) surface. It was found that the in-plane orientation of the quaterphenyl crystallites is determined by aligning the long molecular axes along < 110 >(Au) and < 112 >(Au), facing the aromatic units of the molecules parallel to Au(111). Carbon coverages of 15% or 50% of the An(111) surface cause a change in the orientation of the crystallites and a loss of the epitaxial orientation of the crystallites. In case of 15%, carbon coverage the (201) plane of quaterphenyl crystallites develops parallel to Au(111), and 50% carbon coverage causes a (001) orientation of the crystallites. Both planes are cleavage planes of quaterphenyl. The film morphology consists of aligned needles for quaterphenyl films grown on the clean An(111) surface, bent and randomly oriented needles at 15% carbon coverage and of uniformly distributed hillocks at 50% carbon coverage. The corresponding morphologies can be explained by the crystal structure features of quaterphenyl in combination with the orientation of the molecules within the thin films. (c) 2005 Elsevier B.V. All rights reserved.