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HL: Fachverband Halbleiterphysik

HL 52: Oxide Semiconductors II

HL 52.1: Vortrag

Donnerstag, 20. März 2025, 15:00–15:15, H14

Connection between electronic structure and crystal symme- try in bismuth vanadate — •Philip Schwinghammer, Franziska Hegner, Frederico Delgado, and David A. Egger — Physics Department, TUM School of Natural Sciences, Technical University of Munich, Germany

The electronic and structural properties of bismuth vanadate (BVO) were characterized using density functional theory (DFT). Previous work in the literature indicated that semi-local exchange was incapable of correctly reproducing the ground-state structure of BVO, but disagreed on which functional would improve the description. We found that the Heyd-Scuseria-Ernzerhof hybrid functional could accurately predict the monoclinic ground state structure, provided spin-orbit coupling was included. Semi-local density functionals mischaracterize the hybridization of the lone pair Bi6s states and O2p states near the valence band edge, which is corrected by hybrid functionals. Due to the large mass of bismuth, spin-orbit coupling is required for an accurate description of the electronic structure. When both corrections are taken into account, we find that the valence and conduction band edges in BVO are extremely flat, leading to large effective masses along one direction in reciprocal space. The effective carrier masses are affected by the ionic structure, indicating a possible reason for the different photo-catalytic efficiencies of tetragonal and monoclinic scheelite BVO.

Keywords: BVO; DFT; flat bands; hybrid functional; spin-orbit coupling