Dresden 2011 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 44: Poster Session I
HL 44.53: Poster
Tuesday, March 15, 2011, 18:00–21:00, P3
Isostructural and heterostructural MgZnO and CdZnO alloys — •André Schleife, Claudia Rödl, and Friedhelm Bechstedt — Institut für Festkörpertheorie und -optik and European Theoretical Spectroscopy Facility, Friedrich-Schiller-Universität Jena, 07743 Jena, Germany
One important goal of materials design is to purposefully tailor the fundamental band gap. Recently, group-II oxides such as MgO, ZnO, and CdO are discussed to possibly supersede the nitrides for certain applications, e.g. in optoelectronics. Since the band gaps of the oxides cover a large spectral range from 1.8 eV (CdO) up to 7.7 eV (MgO), their alloys seem to be promising – unless the different equilibrium crystal structures of the end components (rocksalt-MgO and -CdO vs. wurtzite-ZnO) prevent their application.
By employing three different cluster statistics within a cluster-expansion approach we investigate the impact of different growth conditions on the composition of isostructural and heterostructural MgxZn1−xO and CdxZn1−xO alloys. Our total-energy calculations are based on density-functional theory using a generalized-gradient approximation for exchange and correlation.
We also compute quasiparticle energies using the HSE03+G0W0 approach. This allows us to derive the bowings of fundamental band gaps, which reveal a strongly nonlinear behavior. Using the solution of the Bethe-Salpeter equation for the optical polarization function we investigate the influence of the preparation conditions on the peaks related to bound excitonic states at the absorption edge.