Dresden 2009 – scientific programme

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O: Fachverband Oberflächenphysik

O 42: Poster Session II (Nanostructures at surfaces: arrays; Nanostructures at surfaces: Dots, particles, clusters; Nanostructures at surfaces: Other; Nanostructures at surfaces: Wires, tubes; Metal substrates: Adsorption of O and/or H; Metal substrates: Clean surfaces; Metal substrates: Adsorption of organic/bio moledules; Metal substrates: Solid-liquid interfaces; Metal substrates: Adsorption of inorganic molecules; Metal substrates: Epitaxy and growth; Heterogeneous catalysis; Surface chemical reactions; Ab-initio approaches to excitations in condensed matter; Organic, polymeric, biomolecular films– also with adsorbates; Particles and clusters)

O 42.103: Poster

Wednesday, March 25, 2009, 17:45–20:30, P2

Solving the Bethe-Salpeter equation for Wannier-Mott like excitons in InN, ZnO, and MgO. — •Frank Fuchs, Claudia Rödl, André Schleife, Jürgen Furthmüller, and Friedhelm Bechstedt — Institut für Festkörpertheorie und -optik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany

The accurate calculation and parameter-free prediction of optical spectra including excitonic effects is highly desirable for both fundamental and applied research. Excitonic effects can be treated in the framework of many-body perturbation theory and the Bethe-Salpeter equation (BSE), by solving an eigenvalue problem for the electron-hole Hamiltonian Ĥ.

In this study we investigate the formation of Wannier-Mott like excitonic states below the optical absorption edge for InN, ZnO, and MgO. Using a recently developed numerically efficient method [1] it is possible to obtain converged results for the binding energies of the first shells of Wannier-Mott excitons.

The results are critically compared to the predictions based on the Wannier-Mott two-band model and available experimental data. In comparison to the latter the computed binding energies, if converged, appear to be significantly overestimated. We discuss this with respect to a deficiency in the underlying approximation of a static screening and investigate the possibility to go beyond.

[1] F. Fuchs, C. Rödl, A. Schleife, and F. Bechstedt Phys. Rev. B 78, 085103 (2008)