Dresden 2006 – wissenschaftliches Programm
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MM: Metall- und Materialphysik
MM 25: Poster Session
MM 25.39: Poster
Mittwoch, 29. März 2006, 15:30–17:30, P4
Band-gap variation and structural phase transition in Zn1−xMgxO — •I.V. Maznichenko1, M. Bouhassoune2, A. Ernst2, J. Henk2, P. Bruno2, M. Däne1, D. Ködderitzsch1, I. Mertig1, W. Hergert1, Z. Szotek3, and W.M. Temmerman3 — 1Martin Luther University Halle-Wittenberg, Halle (Saale), Germany — 2Max Planck Institute of Microstructure Physics, Halle (Saale), Germany — 3Daresbury Laboratory, United Kingdom
Oxides are highly interesting materials with a huge potential for future applications. MgO is a well known spacer material in tunnel junctions whereas ZnO has a considerably smaller band gap and is applied for opto-electronic devices. The combination of both in the binary alloy Zn1−xMgxO exhibits extraordinary properties as a function of concentration x. First of all, Zn1−xMgxO undergoes a structural phase transition from the wurtzite structure of ZnO to the rock-salt structure of MgO at x=0.4. Second, the band gap of the alloy changes from 3.4 eV for x=0 to 7.2 eV for x=1. First-principle studies of the band gap as a function of concentration and the phase diagram based on total energy calculations of the alloy Zn1−xMgxO are reported. Full charge density-functional calculations in local-density approximation (DFT-LDA) were performed within the framework of the Korringa-Kohn-Rostoker method. The substitutional disorder was treated within the coherent potential approximation (CPA). For the Zn-3d levels we used the local self-interaction correction (SIC). The presented first-principle calculations are in good agreement with experimental results and demonstrate that a proper description of oxide semiconductors requires a treatment beyond LDA.