Regensburg 2007 – scientific programme

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DS: Fachverband Dünne Schichten

DS 25: Symposium: Real Time Growth Studies III

DS 25.1: Invited Talk

Thursday, March 29, 2007, 15:00–15:45, H32

Pentacene thin film growth — •George Malliaras — Cornell University, Ithaca, NY, USA

Organic thin film transistors (OTFTs) are being developed in academic and industrial labs for "disposable" plastic electronics such as radio-frequency identification tags. Among the most promising organic semiconductors is pentacene, which yields transistors with performance similar to that of amorphous silicon. The interfaces of pentacene films with dielectric materials (gate oxide) and conductors (electrodes) play a major role in determining OTFT performance. X-ray scattering has proved to be superb tool for the study of crystalline organic films such as pentacene. My talk will focus on the interface of pentacene films with dielectric materials. Recent studies of growth of pentacene films on silicon oxide has revealed interesting new physics: For example, layer-by-layer growth can be obtained despite the fact that the interaction of pentacene with itself is stronger that that with the substrate. I will discuss our current understanding of how the kinetics of growth affects film morphology. A second topic that will be overviewed is the evolution of structure of organic films with film thickness. As organics are highly polymorphic, they usually adopt a *thin-film* phase at the substrate, with the bulk phase not seen until film thickness has exceeded a certain thickness. I will show that the nucleation of the bulk phase begins at the substrate, but it remains undetected due to the fact that bulk crystallites scatter incoherently. Implications of this phase co-existence on the electrical properties of organic films will be discussed.