Berlin 2018 – scientific programme

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DS: Fachverband Dünne Schichten

DS 22: Optical Analysis of Thin Films (Reflection, Ellipsometry, Raman, IR-DUV Spectroscopy, ...): Session II

DS 22.2: Talk

Wednesday, March 14, 2018, 15:15–15:30, H 0111

Temperature dependent dielectric function of CuI — •Evgeny Krüger, Vitaly Zviagin, Chang Yang, Rüdiger Schmidt-Grund, and Marius Grundmann — Universität Leipzig, Felix-Bloch-Institut für Festkörperphysik, Linnéstr. 5, Leipzig

We present optical and structural properties of CuI thin films deposited by sputtering at temperatures varying from 55^∘C to 310^∘C on c-sapphire substrate. Scanning electron microscopy scans reveal a smooth surface morphology for films grown at temperatures above 160^∘C and large thickness inhomogeneity for films grown at lower temperatures. X-ray diffraction reveals good crystal quality for growth temperatures above 200 ^∘C. The dielectric function (DF) was determined in a wide spectral range between (0.5 – 8.5) eV and for temperatures from 10 K to 300 K. The main features in the DF were assigned to exciton-related optical transitions at various critical points in the Brilluoin zone, revealing non-monotonic temperature dependence of the energy as well as strong screening for excitons related to higher critical points.