First-principles and experimental characterization of the electronic and optical properties of CaS and CaO
Creators
- 1. Université catholique de Louvain, Institute of Condensed Matter and Nanosciences, NAPS Chemin des étoiles 8, bte L07.03.01, B-1348 Louvain-la-Neuve, Belgium
- 2. CERDECAM, Institut Supérieur Industriel ECAM, Promenade de l'Alma 50, B-1200 Bruxelles, Belgium
- 3. LumiLab, Ghent University, Krijgslaan 281-S1, 9000 Gent, Belgium
- 4. Mitsubishi Chemical Group, Science and Technology Research Center, Inc., 1000, Kamoshida-cho, Aoba-ku, Yokohama 227-8502, Japan
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Description
Doped alkaline-earth chalcogenides are interesting photoluminescent materials for opto-electronic applications. It is crucial to have an extended knowledge about the undoped bulk CaS and CaO since all the excited state properties of the doped material heavily depend on it. In this work we investigate the structural parameters, electronic band structures, macroscopic dielectric constants and absorption spectra for CaS and CaO compounds. Their quasi-particle band structure in the GW approximation yields a value of 4.28 eV and 6.02 eV for the indirect theoretical particle gap of CaS and CaO, respectively. The imaginary part of the macroscopic dielectric function e(omega) is computed including excitonic effects through the Bethe–Salpeter equation. The onset of absorption is within 0.1 eV of the experimental one and the calculated spectrum shows a qualitative agreement with experiment. Our computed exciton binding energies are 0.27 eV and 0.40 eV for CaS and CaO, respectively.
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References
Journal reference (Paper in which the method is described) S. Poncé, B. Bertrand, P.F. Smet, D. Poelman, M. Mikami, and X. Gonze, Optical Materials 35, 1477 (2013), doi: 10.1016/j.optmat.2013.03.001
Journal reference (Paper in which the method is described) S. Poncé, B. Bertrand, P.F. Smet, D. Poelman, M. Mikami, and X. Gonze, Optical Materials 35, 1477 (2013)