Growth and morphology of thin films of aromatic molecules on metals: the case of perylene

Abstract

The morphology and growth of perylene films on copper and gold surfaces have been characterized by XPS, AFM, SEM and polarization microscopy. Deposition at cryogenic temperatures leads to amorphous but homogeneous films whereas growth a room temperature results in a formation of disjointed crystalline islands. A similar morphology was observed after thawing the amorphous films which were grown before at low temperature and hence demonstrates a pronounced dewetting. Furthermore, it was found that the geometry of the resulting islands depends on the actual substrate surface which is attributed to the formation of seed layers and their influence on the subsequent film growth. The presently described dewetting and island formation appears to be a quite general phenomenon of organic film growth which needs to be considered in the interpretation of spectroscopic data and STM measurements for organic thin films.