(In)GaAsN bulk layers and quantum wells usually demonstrate lower photoluminescence intensity than the nitrogen-free compositions. In the present work we have carefully optimized both conductance and operation of a nitrogen plasma source as well as growth parameters of GaAsN layers. We found conditions when incorporation of nitrogen did not lead to formation of additional nonradiative recombination. There is some minimum growth rate to obtain good crystal and optical quality of GaAsN. At growth rates below this value the pattern of reflection high energy electron diffraction turns spotty and the growth proceeds in a three-dimensional mode. This leads to a steep decrease in luminescence efficiency of the grown layer. The minimum value of growth rate depends on nitrogen content and growth temperature. Defects caused by low temperature growth are removed by post-growth annealing. We achieved the same radiative efficiency of GaAsN samples with nitrogen content up to about 1.5% grown at 520 degreesC as that of a reference layer of GaAs grown at 600 degreesC. Compositional fluctuation in the GaAsN layers leads to the S-shape temperature dependence of photoluminescence peak position. Post-growth annealing reduces compositional fluctuation.