Dresden 2009 – scientific programme
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O: Fachverband Oberflächenphysik
O 49: Ab-initio approaches to excitations in condensed matter II
O 49.7: Talk
Thursday, March 26, 2009, 12:00–12:15, SCH 251
Influence of free carrier absorption on the optical spectrum of ZnO — •André Schleife1,2, Emmanouil Kioupakis2, Patrick Rinke2, Claudia Rödl1, Frank Fuchs1, Chris G. Van de Walle2, and Friedhelm Bechstedt1 — 1Institut für Festkörpertheorie und -optik, Jena, Germany — 2Materials Department, University of California, Santa Barbara, USA
For optoelectronic devices such as light emitting or laser diodes as well as solar cells an important aspect is the availability and controllability of transparent conducting materials. Zinc oxide as a transparent conducting oxide is strongly in the focus of scientific interest.
In this ab-initio study we investigate the impact of electrons in conduction bands on the optical properties. By employing density functional theory within a generalized-gradient approximation and making use of the projector-augmented wave method, we compute all-electron wave functions. They allow the calculation of optical transition matrix elements. We explicitly elucidate the Burstein-Moss shift due to the occupancy of conduction bands as well as the absorption caused by conduction-conduction band transitions on the level of the random-phase approximation within the independent quasiparticle approximation. Both effects are analyzed regarding their dependence on the free carrier concentration.
Consequences for the transparency of zinc oxide will be discussed including the dependence on the free carrier concentration.