Abstract
AbstractIn the past few years there has been an explosion of interest in electronic devices made from organic molecules for application in field effect transistors (FET). Pentacene is of particular interest because of its high field effect charge mobility in single crystal state, which approaches that of amorphous silicon. The electrical properties of polycrystalline films are inferior to those of single-crystal materials. Growth of appropriately oriented polycrystalline pentacene film may improve the charge mobility. In this work, we used self-assembled monolayers (SAMs) as alignment film to influence the orientation of pentacene film grown on it. For this purpose, pentacene films deposited on SAMs bearing different terminal functional groups have been studied by reflection-absorption IR, AFM, SEM, XRD and NEXAFS analyses. A film with roughly perpendicularly-oriented pentacene molecules was observed on SAM-covered Au surfaces, whereas parallel alignment was observed on bare Au surface. The X-ray photoemission electron microscope (X-PEEM) was used to analyze the orientation of pentacene molecules deposited on SAM patterned Au surface. The observation of highly oriented organic molecular crystal packing in these studies provides a chance for probing the carrier transport behavior via p-p stacking and intermolecular hopping mechanisms through the pentacene molecular crystals.