Origins for epitaxial order of sexiphenyl crystals on muscovite(00I)

Abstract

The epitaxial order of sexiphenyl crystals on muscovite(00I) is investigated by x-ray diffraction, lattice misfit calculations and atomic force microscopy. Depending on the substrate temperature during the thin film growth process, different epitaxial orientations are formed. Sexiphenyl thin films prepared at 37Q K preferentially form crystals with the crystallographic (11-1) planes parallel to the substrate surface while at 434 K a strong fraction of crystals with (11-2) orientations is grown. The epitaxial orders of sexiphenyl crystals are compared with lattice misfit calculations. The in-plane order of the {11-1} crystals can be explained by a point-on-line coincidence I, which reveals that the interface is formed by undisturbed crystal surfaces. The epitaxial order of the {11-2} oriented crystals is characterised by the experimental observation that low indexed crystal directions in the sexiphenyl(11-2) plane and the muscovite(001) surface coincide with each other, forming a near-coincidence case. Corrugations of the substrate surface are responsible for this second type of epitaxial order. Characteristic features in the thin film morphology could be correlated to the two observed epitaxial orientations of the sexiphenyl crystals. Copyrigh © 2009 John Wiley & Sons, Ltd.