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DS: Fachverband Dünne Schichten
DS 37: Focussed Session: Oxide semiconductors II (joint session with HL)
DS 37.9: Vortrag
Donnerstag, 19. März 2015, 17:45–18:00, H 2032
Determination of subgap states in oxides: a challenge for DFT functionals — Wolfgang Körner1, •Daniel F. Urban1, David Munoz Ramo2, Paul D. Bristowe2, and Christian Elsässer1,3 — 1Fraunhofer Institute for Mechanics of Materials IWM, Freiburg, Germany — 2Department of Materials Science and Metallurgy, University of Cambridge, United Kingdom — 3Institute for Applied Materials, Karlsruhe Institute of Technology
We present a density-functional-theory analysis of crystalline and amorphous Zn- and Sn-based oxide systems which focuses on the electronic defect-states within the band gap [1]. A comparison of these electronic levels reveals that the hybrid DFT exchange-correlation functionals PBE0, HSE06 or B3LYP agree with a self-interaction corrected local-density approximation (SIC-LDA) functional on occupied defect levels when similar treatments of the self-interaction are considered. However, for unoccupied levels the hybrid functionals and the SIC approach lead to very different predictions. We show that a prerequisite for the determination of the energetic position of subgap states in these oxides is that a functional needs to predict correctly the electronic band structure over a wide energy range and not just close to the band gap. We conclude that for accurate defect levels an adequate treatment of the self interaction problem is required especially in the presence of nearby metal-metal interactions.
[1] W. Körner, D. F. Urban, D. Munoz Ramo, P. D. Bristowe, C. Elsässer, Phys. Rev. B 90, 195142 (2014)