Dresden 2009 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 52: Organic semiconductors II
HL 52.2: Talk
Friday, March 27, 2009, 10:30–10:45, POT 51
Growth and Morphology of Three Dimensional Rubrene Single Crystals — •Mira El Helou1,2, Olaf Medenbach3, and Gregor Witte1,2 — 1Molekulare Festkörperphysik, Philipps-Universität Marburg, Germany — 2Physikalische Chemie I, Ruhr-Universität Bochum, Ger — 3Institut für Geologie, Mineralogie und Geophysik, Ruhr-Universität Bochum, Germany
In the fast growing field of organic electronics, organic field effect transistors (OFETs) have become a focus of intense research due to their promising potential in flexible electronics, low-cost devices and large-area applications. Among organic semiconductors the highest room temperature charge carrier mobility has been reported for rubrene crystals (Sundar et al. 2004). So far essentially crystalline platelets of a few microns thickness and (001) orientation were grown (de Boer et al. 2004) while the growth of thicker single crystals became a challenge, due to the conformational change from gas into bulk phase but can be overcome by employing hot wall type deposition (Käfer et al. 2005). Here we report a detailed morphological characterization of bulk crystallites with lateral dimensions of up to 150*m. By using SEM and AFM the equilibrium structure and the topography including the step height of the differently oriented surfaces have been analyzed in detail. The availability of such oriented crystallites allows in particular a precise characterization of optoelectronic properties along different crystallographic directions. As a stating point the refractive indices of the three main crystallographic directions a, b and c at wavelength of 589 nm have been determined.