Using TEM and XRD to probe crystal orientation in organic thin films grown with OMBD

Abstract

Correlating X-ray diffraction data with images of lattice fringes obtained in the transmission electron microscope allows diffraction from planes in crystalline materials to be studied from different perspectives. The focus of this work is on the characterisation of thin films of copper phthalocyanine prepared using organic molecular beam deposition. Films grown on silicon have been studied using X-ray diffraction, which identifies that the (100) plane lies parallel to the substrate surface. Films grown on amorphous carbon have been studied using transmission electron microscopy which confirms that the (001) plane is close to perpendicular to the substrate surface. The promotion of a different crystal orientation can be achieved by deposition of copper phthalocyanine on to a film of perylene tetracarboxylic dianhydride. The X-ray diffraction data of these films shows that the (11-2) plane is now parallel to the substrate surface and this is confirmed by the observation of lattice fringes corresponding to the (100) plane in the transmission electron microscope. The information obtained can be used to correctly predict the angles needed to tilt the sample in the transmission electron microscope to observe lattice fringes from both the (100) and (001) planes in the double layer films.