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HL: Fachverband Halbleiterphysik

HL 48: ZnO: Preparation and characterization II

HL 48.4: Vortrag

Donnerstag, 28. Februar 2008, 10:15–10:30, ER 164

ZnO:Mn^x valence configuration from the perspective of density functional theory — •Marc Andy Gluba and N. H. Nickel — Hahn-Meitner-Institut Berlin GmbH, Abt. Silizium Photovoltaik (SE1), Kekuléstraße 5, D-12489 Berlin, Germany

Zinc oxide (ZnO) doped with transition metal (TM) ions has attracted considerable interest because of its potential application as a base-material for spintronic devices. According to theoretical predictions by Dietl et al. manganese doped into ZnO should preserve its ferromagnetic order up to room temperature[1]. However, the experimental realization of dilute ferromagnetic ZnO is still challenging.

It is widely accepted that TM ions, when incorporated into the ZnO lattice, are isovalent with the zinc ions they substitute for. Thus, Mn in ZnO is commonly present in the divalent charge state for perceptibly high concentrations above 10¹⁹cm⁻³. However, recent electron paramagnetic resonance (EPR) experiments on ZnO with Mn traces of concentrations as low as 10¹⁴cm⁻³ suggest that the Mn charge state can deviate from the divalent configuration[2]. In order to elucidate stable valence configurations of Mn and their respective transition levels bandstructure calculations have been performed in the framework of density functional theory (DFT). The impact of additional on-site coulomb interaction within the local spin density approach (LSDA+U) will be discussed.

[1] T. Dietl et al., Science 287, 1019 (2000)

[2] M. A. Gluba et al., Superlattices and Microstructures (in press)