The effects of doping antimony (Sb) to dilute GaAsNx (x = 0.4%) grown on GaAs by molecular bean epitaxy are investigated. A transition region was found at 5 x 10(-9) < Sb < 10(-8) Torr where below this, Sb behaves as an impurity and above it, Sb acts as a surfactant. Low-temperature (4.5 K) PL peak intensities of prominent emissions were observed at 955 and 10 17 nm in GaAsN: Sb samples. The 955 nm peak is from GaAsN fundamental bandgap transition and the 10 17 nm peak, which was never reported, appears at the same magnitude as the GaAsN peak in higher Sb-doped samples and is reduced with decreasing Sb doping at the 10(-9) Torr range. This peak is related to point defects from Sb-doped III-V nitride under high arsenic overpressure. A blend of AFM, HRXRD and PL is used to characterize the material properties. (C) 2003 Elsevier Science B.V. All rights reserved.