Regensburg 2007 – scientific programme

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SYOE: Symposium Organic Thin Film Electronics: From Molecular Contacts to Devices

SYOE 8: Poster Session SYOE

SYOE 8.45: Poster

Tuesday, March 27, 2007, 18:00–20:00, Poster B

Optical characterization of pentacene thin films by variable angle spectroscopic ellipsometry — •Alexander Hinderhofer, Ute Heinemeyer, Stefan Kowarik, Alexander Gerlach, and Frank Schreiber — Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen

Pentacene has been found to be a promising candidate for both fieldeffect transistors and photovoltaic diodes due to its high mobilities. Pentacene thin films grow in single-crystal grains and show high optical anisotropy with uniaxial symmetry. We use variable angle ellipsometry in transmission as well as in reflection on different substrates to determine the optical constants of the in-plane and the out-of-plane axes. The data analysis of such anisotropic systems is presented and the resulting optical constants are shown. Spectral features related to the vibronic progression and the different transitions (between 1.5-3eV) involved will be discussed. Furthermore, it is possible to take the spectra sufficiently fast to follow organic molecular beam deposition in real time at one fixed angle of incidence. Based on the post-growth results we analyze the real-time data and detect changes in the optical properties during growth.