Dresden 2006 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 23: POSTER Functional Organic Thin Films

CPP 23.13: Poster

Thursday, March 30, 2006, 17:00–19:00, P2

Development of a high performance OFET on well ordered sapphire — •Sönke Sachs, Matthias Paul, Achim Schöll, and Eberhard Umbach — Experimentelle Physik II, Am Hubland, 97074 Würzburg, Germany

The charge carrier mobility in organic field effect transistors strongly depends on the structural quality of the active medium. For thin film transistors the structural order is strongly influenced by the structure, morphology, and interaction potential of the substrate, which in case of a bottom gate geometry is an insulator.

For such a geometry we try to optimize the film growth by using a highly-ordered, clean, and well-characterized single-crystalline (1120) sapphire (α-Al₂O₃) substrate. With the organic semiconductor diindenoperylene (DIP) we demonstrate that the organic film grows polycrystalline with large single crystalline domains. An AFM analysis indicates that under optimized preparation conditions the size of these crystallites is only limited by the dimensions of the substrate terraces. Moreover, XPS and NEXAFS results show only weak interaction at the interface and a preferential upright orientation of the DIP molecules within the crystallites, thus exhibiting very favorable conditions for a high performance OFET. A design for an optimized model OFET is discussed.