First-principles DFTÂ +Â GW study of the Te antisite in CdTe

Formation energies, charge transitions levels, and quasiparticle defect states of the tellurium antisite (TeCd) in CdTe are addressed within the DFT + GW formalism. We find that (TeCd) induces a (+2/0) deep level at 0.99 eV above the valence band maximum, exhibiting a negative-U effect. Moreover, the calculated zero-phonon line for the excited state of (TeCd)0 corresponds closely with the ∼1.1 eV band, visible in both luminescence and absorption experiments. Our results differ from previous theoretical studies, mainly due to the well-known band gap error and the incorrect position of the band edges predicted by standard DFT calculations.