We investigated the effect of atomic H irradiation on thin-film growth of GaInNAs by hydrogen-assisted RF-molecular beam epitaxy (RF-MBE) from the viewpoint of growth dynamics and crystal quality. The crystal quality of GaInNAs was characterized by X-ray diffraction and photoluminescence (PL), and the surface morphology was characterized by using atomic force microscope. The atomic H irradiation during the growth of GaInNAs in RF-MBE was found to be effective in improving the overall quality of the epilayers. Further, it was found that atomic 14 irradiation has an effect of suppressing the three-dimensional growth thereby promoting a two-dimensional growth as well as is effective in passivating the defects and suppressing the recombination from localized states. Low temperature (77 K) PL measurements showed that the incorporation of N into InGaAs effectively reduces the emission energy. An emission enhancement in GaInNAs grown with atomic H was observed at 1.2 mum. (C) 2002 Elsevier Science B.V. All rights reserved.