Band gap anomalies of the (ZnM2O4)-O-III (M-III = Co, Rh, Ir) spinels
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Scanlon, DO, Watson, GW, Band gap anomalies of the (ZnM2O4)-O-III (M-III = Co, Rh, Ir) spinels, Physical Chemistry Chemical Physics, 13, 20, 2011, 9667-9675Download Item:
Abstract:
Development of high figure-of-merit p-type transparent conducting oxides has become a global research goal. ZnM 2 IIIO 4 (M III = Co, Rh, Ir) spinels have been identified as potential p-type materials, with ZnIr 2O 4 reported to be a transparent conducting oxide. In this article the geometry and electronic structure of ZnM 2 IIIO 4 are studied using the Perdew-Purke-Ernzerhof generalized gradient approximation (PBE-GGA) to density functional theory and a hybrid density functional, HSE06. The valence band features of all the spinels indicate that they are not conducive to high p-type ability, as there is insufficient dispersion at the valence band maxima. The trend of increasing band-gap as the atomic number of the M III cation increases, as postulated from ligand field theory, is not reproduced by either level of theory, and indeed is not seen experimentally in the literature. GGA underestimates the band-gaps of these materials, while HSE06 severely overestimates the band-gaps. The underestimation (overestimation) of the band-gaps by GGA (HSE06) and the reported transparency of ZnIr 2O 4 is discussed.
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http://people.tcd.ie/watsongDescription:
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Author: WATSON, GRAEME WILLIAM
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Physical Chemistry Chemical Physics;13;
20;
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