Optical quality of GaNAs and GaInNAs quantum wells and its dependence on RF radical cell operation in chemical beam epitaxy (CBE) were investigated. It was shown that nitrogen atoms are main plasma species responsible for the CBE growth of GaNAs and related alloy. By choosing aperture flow conductance, significant improvement in photoluminescence of GaInNAs/GaAs quantum well at 1.2 mu m wavelength region have been demonstrated. The reduction of ions are found to be effective to improve crystal quality.