Stenuit G, Fahy S

Ab initio Troullier-Martins and empirically adjusted Hartwigsen-Goedecker-Hutter pseudopotentials have been used, within the density-functional theory (DFT) framework, to study the optical transitions in the dilute nitride, GaNxAs1-x. Composition dependence of the energy gap (E-) and the E+ optical transitions have been computed with the two pseudo potentials. Band anticrossing (BAC) model parameters have been derived from the composition dependence of the DFT E- and E+ optical transitions, providing DFT-based analytical expressions for E+(x) and E-(x). The influence of the N configuration (ordered or randomly distributed in the GaAs host material) has been studied. Random distribution is found to increase the energy gap E-, compared to ordered structures, but has relatively little effect on the E+ energy. Comparisons with the experimental and tight-binding data are reported. (C) 2009 Elsevier Ltd. All rights reserved.