Examinando por Autor "Flores, Mauricio A."

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    First-principles DFT + GW study of the Te antisite in CdTe
    (Elsevier, 2016-12) Flores, Mauricio A.; Orellana, Walterc; Menéndez-Proupin, Eduardo
    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. © 2016 Elsevier B.V.
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    Self-compensation in chlorine-doped CdTe
    (Nature Publishing Group, 2019-12) Orellana, Walter; Menéndez-Proupin, Eduardo; Flores, Mauricio A.
    Defect energetics, charge transition levels, and electronic band structures of several Cl-related complexes in CdTe are studied using density-functional theory calculations. We investigate substitutional chlorine (ClTe and ClCd) and complexes formed by ClTe with the cadmium vacancy (ClTe-VCd and 2ClTe-VCd) and the TeCd antisite (ClTe-TeCd). Our calculations show that none of the complexes studied induce deep levels in the CdTe band gap. Moreover, we find that ClTe-VCd and ClTe are the most stable Cl-related centers in n-type and p-type CdTe, under Te-rich growth conditions, showing shallow donor and acceptor properties, respectively. This result suggests that the experimentally-observed Fermi level pinning near midgap would be originated in self-compensation. We also find that the formation of the ClTe-TeCd complex passivates the deep level associated to the Te antisite in neutral charge state. © 2019, The Author(s).