Mossbauer spectra and the DX-centre complex in AlGaAs

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Abstract
Mossbauer spectra for the 'DX' deep-level defect in AlGaAs alloys are just now being made available-for example, in a recent article by Gibart and co-workers. The interpretation of these spectra has been somewhat clouded by the fact that Mossbauer specialists have generally not considered the anti-site defect among the defect complexes present in III-V crystals near the Mossbauer isotope that affect the various components of the spectra. The author notes that the anti-site defect is well established as a component of, for example, the EL2 deep-level defect, and generally as the most prevalent native point defect in III-V crystals. Furthermore, the spectra reported by Gibart and co-workers are consistent with the model wherein the 'X' of the DX defect complex is the pair composed of a metal-on-As-site anti-site defect plus a Ga vacancy that results from As vacancy nearest-neighbour hopping. In particular, they show that a major fraction of donors remain in an unperturbed state when DX compensates the sample.