Dresden 2009 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 24: Organic Thin Films IV
DS 24.2: Vortrag
Mittwoch, 25. März 2009, 16:45–17:00, GER 38
Model calculations on the in-plane optical anisotropy of copper-phthalocyanine films — •Michael Fronk, Dietrich R.T. Zahn, and Georgeta Salvan — Physics Department, Chemnitz University of Technology, D-09107 Chemnitz
Copper-phthalocyanine (CuPc) films prepared by organic molecular beam deposition on H-passivated silicon and Si covered with native oxide were investigated by means of ellipsometry and reflection anisotropy spectroscopy (RAS). In addition to the in-plane − out-of-plane anisotropy found from the evaluation of the ellipsometry data [1] an in-plane anisotropy in the order of 10−2 was observed by RAS. In a first step model calculations assuming homogeneous in-plane anisotropy over the whole layer thickness were performed in order to extract the anisotropy in the optical constants n and k. While the spectral shape of the anisotropy in k indicates that each optical transition dipole has a different preferential azimuthal orientation in the CuPc film on H-Si, all transition dipoles appear to be aligned in the same direction for CuPc on Si+SiO2. For the latter films the in-plane anisotropy was also found to increase with increasing thickness. For a detailed understanding of the azimuthal orientation of the optical transition dipoles the angle resolved RAS data were fitted. More advanced models taking into account a change in the anisotropy with film thickness were built in order to describe the spectral evolution with film thickness.
[1] O.D. Gordan et al., Organic Electronics 5, 2004, 291