Regensburg 2013 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 58: Poster Session III (Solid-liquid interfaces; Scanning probe and other methods; Electronic structure theory; Spin-orbit interaction)

O 58.20: Poster

Mittwoch, 13. März 2013, 18:15–21:45, Poster B1

Dielectric Properties of Functional Oxide thin-films from First Principles — •Jawad Alsaei¹, Neal Alford², Paul Tangney¹, and Arash A. Mostofi¹ — ¹Departments of Materials and Physics, Imperial College London, SW7 2AZ, United Kingdom. — ²Department of Materials, Imperial College London, SW7 2AZ, United Kingdom.

Perovskite oxide materials show a wide range of physical properties that make them interesting both technologically and scientifically. Particular attention has been drawn to perovskites in thin-film form in order to meet the demand of manufacturing smaller industrial components such as advanced integrated electronic devices.

The optical properties of thin-film perovskite oxides can differ significantly from those of the bulk due to several factors, such as the mismatch strain imposed by the substrate, cation substitution, point defects, etc. We investigate, from first principles, the effect of some of these factors on the optical properties of functional oxide materials (BaTiO₃ and SrTiO₃).

First, it is found that the refractive index, at (400-1600 nm), increases with applied uni-axial strain. Second, the optical properties of Ba_xSr_1−xTiO₃ (BSTO) solid solutions are studied using both the supercell and the virtual-crystal approximation (VCA) approaches. It is found, surprisingly perhaps, that the two methods agree remarkably well. Third, the effect of Sr content in BSTO is investigated. It is found that the refractive index decreases almost linearly as the Sr:Ba ratio increases. Finally, the effect of Oxygen vacancies is studied.