Hybrid functional calculations of a Te antisite in bulk CdTe

University essay from Uppsala universitet/Materialteori

Author: Kristinn Björgvin Árdal; [2013]

Keywords: CdTe; DFT; antisite; PBE; HS0E6;

Abstract:

The detection of gamma-rays is an important issue in a cast array ofindustries. CdTe is a semiconductor used for gamma-ray detectors whichcan operate at high temperatures. Density functional theory calculationsof the electronic structure within the Perdew-Burke-Ernzerhof exchange-correlation functional underestimate the bandgap of CdTe: the calculatedbandgap within PBE is less than half the experimental value. The useof a hybrid functional approach to exchange and correlation describes thebandgap correctly. The goal of this project was to nd out if PBE calcu-lations give an adequate description of defects in CdTe by comparing it tohybrid functional calculations. We show that PBE is adequate in describ-ing Te antisite defects in CdTe if a correction to the bandgap is applied.The defect level for both PBE and hybrid functional was calculated to be0.24 eV above the valance band.

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