Dresden 2003 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 20: POSTER A

CPP 20.54: Poster

Montag, 24. März 2003, 19:00–21:00, ZEU/250

Modeling of the anisotropic dielectric function for perylene films — •Christian Dahmen, Oliver Kappertz, and Matthias Wuttig — I. Physikalisches Institut A, RWTH Aachen

During the last years organic materials have received increasing attention due to their interesting optical and electronic properties. Polycyclic aromatic hydrocarbons are both interesting and challenging, since their strong π-electron interaction leads to anisotropic properties such as anisotropic conduction and uniaxial optical behavior. The precise determination of the dielectric function is necessary for quantitatively understanding these properties. We have used anisotropic ellipsometry to analyze thermally grown perylene films with thicknesses of tenth of micrometers deposited on quartz substrates. A Cauchy model is used for the in-plane and out-of-plane index of refraction and accurately describes the behavior in the visible range. Lorentz oscillators are employed to model the absorption in the VIS/UV region, which also allows classification of the different excitations found in this region. We have applied this model to films of varying thickness and on several substrates. The good reproducibility points towards an thorough understanding of the underlying processes.