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O: Fachverband Oberflächenphysik
O 90: Semiconductor Substrates
O 90.2: Talk
Friday, March 15, 2013, 10:45–11:00, H45
Concentration of point defects at metal-oxide surfaces: case study of MgO (100) — Norina A. Richter1, Sabrina Sicolo2, •Sergey V. Levchenko1, Joachim Sauer2, and Matthias Scheffler1 — 1Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin-Dahlem 14195, Germany — 2Humboldt-Universität zu Berlin, Berlin 10099, Germany
We calculate from first principles the concentration of neutral and charged oxygen vacancies on a doped MgO (100) surface at realistic (T, pO2) conditions. Vacancy formation energies are computed using hybrid density-functional theory with parameters of the exchange-correlation functional adjusted according to a basic consistency requirement on the Kohn-Sham and G0W0 defect transition levels. The parameters are validated by CCSD(T) calculations of formation energies for neutral vacancies using embedded cluster models. Gibbs free energies of formation are obtained using the ab initio atomistic thermodynamics approach [1]. We demonstrate that the concentration of surface vacancies is significantly increased due to band bending and Fermi level pinning at the surface, resulting in lower formation energies of charged vacancies.
[1] K. Reuter and M. Scheffler, Phys. Rev. B 65, 035406 (2001); C. M. Weinert and M. Scheffler, Mat. Sci. Forum 10-12, 25 (1986); M. Scheffler and J. Dabrowski, Phil. Mag. A 58, 107 (1988).