Growth and morphology of pentacene films on oxide surfaces

Pentacene thin films were grown in ultra high vacuum on amorphous SiO₂ and on a high dielectric constant material, crystalline BaTiO₃. During pentacene deposition, substrates were held at three different temperatures (-65⁰, 25⁰ and 75⁰ C). In general, three different morphologies were identified: A first closed interfacial layer, a thin film mode composed of faceted grains with single molecule step height, and a volume mode with features substantially higher than those of the film mode. Analysis was carried out by atomic force microscopy and in some cases by synchrotron X-ray diffraction.