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Published online by Cambridge University Press: 10 February 2011
The near-infrared photoluminescence of high purity, nominally undoped MOVPE AlGaAs was investigated as a function of growth temperature, aluminum content and hydrostatic pressure. Two PL bands, observed at ˜1.1 eV and ˜0.8 eV independent of aluminum content, were attributed to oxygen-related defects based on the correlation of emission intensity and oxygen concentration. Hydrostatic pressure experiments, along with the measurement temperature dependence, suggest that the ˜0.8 eV band is due to emission from an oxygen-related mid-gap level to a shallow acceptor or the valence band, depending on temperature. A tentative defect model based on the off-center OA, defect in bulk GaAs and variations in the number of nearest neighbor aluminum atoms is proposed to explain the two PL bands and the dependence of their relative intensity on aluminum content.