AVS 53rd International Symposium
    Electronic Materials and Processing Thursday Sessions
       Session EM-ThM

Paper EM-ThM6
Growth of Pentacene Films: Influence of Substrates

Thursday, November 16, 2006, 9:40 am, Room 2001

Session: Organic Electronic Materials and Devices
Presenter: G. Witte, Ruhr-University Bochum, Germany
Authors: G. Witte, Ruhr-University Bochum, Germany
D. Kaefer, Ruhr-University Bochum, Germany
Ch. Woell, Ruhr-University Bochum, Germany
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In recent years organic semiconductors have gained wide-spread attention due to their promising potential as active materials for organic electronic applications. Of particular interest among such materials are oligoacenes, such as pentacene, because of their ability to form crystalline phases which reveal remarkable high carrier mobilities. In view of the interrelation between intermolecular packing and electronic properties a precise control of the molecular packing and orientation in thin (poly-) crystalline films is of vital interest especially for devices such as OFETs where high charge carrier mobilities are required. Here we report the result of a comprehensive growth study of thin pentacene films deposited by OMBD under vacuum conditions onto various metal surfaces. By combining different microscopy techniques including STM, AFM, SEM with X-ray absorption spectroscopy (NEXAFS) the evolution of such organic films has been analyzed as a function of thickness and deposition parameters (rate and temperature). We demonstrate that the resulting molecular orientation and the film morphology depend critically on the roughness and chemical termination of the substrate whereas growth rate and substrate temperature mainly affects the grain size. Dewetting phenomena which usually dominate the morphology of pentacene films on clean metal substrates can be suppressed by first coating the substrate with self-assembled monolayers (SAMs) which leads to rather smooth films. Possible driving forces for the appearance of the various film structures and strategies for a rational control of the microstructure of such organic films are discussed.