Dresden 2009 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 21: Organic Thin Films I

DS 21.3: Vortrag

Mittwoch, 25. März 2009, 10:00–10:15, GER 38

Microscopic Origin of Pentacene OFET improvement by usage of Pd electrodes — •Daniel Käfer¹, Gregor Witte², Claudia Bock³, Ulrich Kunze³, and Christof Wöll¹ — ¹Physikalische Chemie I, Ruhr-Universität Bochum, 44780 Bochum — ²AG Molekulare Festkörperphysik, Philipps-Universität Marburg, 35032 Marburg — ³Lehrstuhl für Werkstoffe und Nanoelektronik, Ruhr-Universität Bochum, 44780 Bochum

Due to its high charge carrier mobility pentacene is a promising molecular semiconductor for the fabrication of organic field-effect transistors (OFETs). While gold has been commonly used as electrode material in pentacene-based thin film transistors a strong increase in the charge carrier mobility and decrease in contact resistance and activation energy can be achieved using Pd electrodes instead. On the one hand, the improved device characteristics for Pd electrodes are caused by an advantageous morphology and a different microscopic orientation compared to the growth of pentacene on Au electrodes as revealed by a combination of microscopic (AFM, SEM), spectroscopic (NEXAFS) and diffraction (XRD) techniques. A detailed UPS study, on the other hand, indicates that also different electronic properties like the absence of an interface dipole and a low hole injection barrier cause the superior device performance. The importance of these pentacene film parameters for a resulting OFET will be discussed.