Dresden 2017 – scientific programme
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DS: Fachverband Dünne Schichten
DS 16: Layer Properties: Electrical, Optical, and Mechanical Properties I
DS 16.4: Talk
Monday, March 20, 2017, 17:45–18:00, CHE 91
Optical Characterization of Anisotropic Thiophene-Phenylene Co-oligomer Micro Crystals by Spectroscopic Imaging Ellipsometry — •Christian Röling1, Elena Y. Poimanova2, and Vladimir V. Bruevich3 — 1Stresemannstrasse 30, 37079 Göttingen — 2Donetsk National University, Department of Chemistry, Ukraine — 3International Laser Center & Physics Faculty, M.V. Lomonosov Moscow State University, Vorobyevy gory, Moscow
Here we demonstrate Imaging Ellipsometry as a combination of microscopy and ellipsometry to characterize even micro-sized thin film crystals on plane surface regarding anisotropy, optical properties, crystalline domains and thickness. The semiconducting thiophene-phenylene co-oligomer 1,4-bis(5'-hexyl-[2,2'-bithiophen]-5-yl)benzene (dHex-TTPTT) crystals were grown by solvent based self-assembly technique on silicon substrate with 300 nm thermally silicon dioxide. The ellipsometric measurements were performed with an Ep4-SE (Accurion). In an ellipsometric high-contrast image of the complete sample we have localized high quality single crystals. After demonstrating the biaxial anisotropy of the crystal by using Müller-Matrix imaging ellipsometry we determined the optical axes by rotating the sample and performed spectroscopic measurements (λ = 400-700 nm) in 5 nm intervals. The optical properties were described by using a Lorentz term in the Ep4-Model. After determining the dispersion of the crystals we converted a recorded Delta and Psi-map into a 2D thickness image. Based on a quantitative analysis of the resulting thickness map we have calculated the height of a molecular layer (3.49 nm).