A study was made of the photoluminescence from samples with N contents of less than 0.5%. The low-temperature photoluminescence spectra were composed of several excitons bound to N complexes; each of which was associated with a different composition or configuration. The dependence of the binding energy, of the predominant recombination center, upon the N concentration was explained in terms of a hierarchy of N complexes: from centres which comprised at least two N atoms to more extended clusters. The excitonic transitions were very sensitive to growth parameters and could be used to study the statistical distribution of N in nominally uniform layers.

Excitons Bound to Nitrogen Clusters in GaAsN S.Francoeur, S.A.Nikishin, C.Jin, Y.Qiu, H.Temkin: Applied Physics Letters, 1999, 75[11], 1538-40