GaAs1-xNx epilayers were grown on GaAs(001) by organometallic vapor-phase epitaxy at temperatures T-s = 500-650 degrees C from trimethylgallium, tertiarybutylarsine, and 1,1-dimethylhydrazine (DMHy) to investigate nitrogen incorporation. Secondary ion mass spectrometry depth profile measurements indicate that N concentrations are uniform across the film thickness for x up to 0.0375. Attempts to reach higher concentrations lead to phase separation and drastically reduced growth rates due to passivation of the adsorption sites by DMHy. At a given growth temperature, the ratio x/(1-x) can be related to X-v/(1-X-v), where X-v is the DMHy fraction of total group-V precursors flow, by a power law of the form x/(1-x) = 10(-A)[X-V/(1-X-V)](B). Between 500 and 550 degrees C, the exponent A remains close to 2.5-2.6, then increases to reach 3.7 at T-s = 600 degrees C, indicative of the intrinsically lower efficiency of N incorporation at high temperatures. Exponent B, however, is higher at 600 degrees C (B approximate to 1.9) than at 500 or 550 degrees C (B approximate to 1.2), indicating that x increases at a higher rate with respect to Xv for higher T,. This makes the 550-600 degrees C temperature range more attractive than initially reported for the growth of GaAs1-xNx with high N content. Our results also indicate that DMHy is significantly affecting Ga incorporation kinetics, as evidenced by the intricate relationship between the DMHy flow, the temperature, and the growth rate. For instance, DMHy stabilizes the kinetically limited growth regime up to 575 degrees C, where the growth rate of GaAs1-xNx can exceed the one observed for GaAs. At 600 degrees C, though, the GaAs1-xNx growth rate is systematically decreased with the incorporation of nitrogen. (C) 2007 Elsevier B.V. All rights reserved.