Photoluminescence efficiency was enhanced in molecular-beam-epitaxial-grown 1.55-μm GaInNAsSb single quantum wells through modulation of the arsenic and antimony fluxes. The arsenic-to-antimony flux ratio was found to be a key consideration at reduced group-V fluxes in maintaining the beneficial effects of antimony while reducing the number of point defects, most likely arsenic antisites. Samples were also characterized by high-resolution x-ray diffraction, secondary ion mass spectrometry, and low-temperature photoluminescence. These findings offer a means to substantially reduce dilute-nitride laser threshold current densities.