Dresden 2014 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 84: Poster: Electronic structure theory / Carbon (other than graphene) / Si, Ge, and SiC / III-V semiconductors (other than nitrides)
HL 84.2: Poster
Mittwoch, 2. April 2014, 17:00–20:00, P1
Defect energy levels: Hybrid density functional theory vs. many-body perturbation theory — •Wei Chen and Alfredo Pasquarello — Chaire de Simulation à l’Echelle Atomique (CSEA), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
We establish a consistent description of the thermodynamic charge transition levels of localized point defects through hybrid density functional theory and many-body perturbation theory. Three point defects are presented in this work, including a color center (a fluorine vacancy) in lithium fluoride, an oxygen interstitial in silicon oxide, and a carbon split interstitial with ⟨ 100 ⟩-orientation in cubic silicon carbide. The choice of the defects spans atomically localized defects in both ionic insulators and covalent semiconductors. The hybrid-functional calculations are performed using the PBE0 and the range-separated HSE functionals. The G0W0 calculations are performed on top of PBE eigenvalues and eigenstates. We find that the total-energy difference method using (hybrid) density functionals yields remarkably compatible charge transition levels relative to the higher level G0W0 approach, provided the electronic structures are aligned with respect to the electrostatic potential. We highlight the importance of the finite-size effect, the delocalization error, and the choice of the calculation path in the G0W0 scheme of the defect level calculation. Our results substantiate the need of a correct description of the band edges in the prediction of defect energy levels.