Regensburg 2013 – scientific programme

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DS: Fachverband Dünne Schichten

DS 11: Poster Session I: Application of thin films; Ion beam induced surface patterns; Ion and electron beam induced processes; Micro- and nanopatterning (jointly with O)

DS 11.1: Poster

Monday, March 11, 2013, 17:00–20:00, Poster B1

Optical and structural properties of ZnCo₂O₄ under different growth conditions — •Vitaly Zviagin, Tammo Böntgen, Rüdiger Schmidt-Grund, Michael Lorenz, and Marius Grundmann — Universtät Leipzig, Institut für Experimentelle Physik II, Linnéstr. 5, Germany

We present an investigation of optical and structural properties of ZnCo₂O₄ thin films in dependence on the growth conditions. The films were grown on an a-sapphire substrate by pulsed layer deposition at different oxygen partial pressures. The optical properties were determined by spectroscopic ellipsometry (SE) in the range from 0.5 eV to 9.0 eV. A model was developed for the measured dielectric function (DF) of the ZnCo₂O₄. Our model consists of Gauss- and critical-point-functions located at the optical transition energies. Transmission measurements in the same spectral range were carried out and reveal weak absorption bands below the band gap. The positions of the bands correspond to d-d transition of Co²⁺ known to arise in ZnCo₂O₄[1]. The thickness of the thin films and surface topology, estimated from atomic force microscopy and scanning electron microscopy, are comparable to the SE estimations. The crystal structure of the films was determined from the wide-angle X-ray diffraction scans which are presented and compared in dependence on the oxygen partial pressure of the film deposition. It was determined that the partial pressure during the deposition induces a distinct shift in the observed transition energies as well as clear dependence in the crystallography and surface topology of the thin films. [1] Wang et al., J. Alloys Compd. 520 (2012) 158.