Antimony has been used as a surfactant to improve the quality of GaInNAs/ GaAs quantum wells for long-wavelength optoelectronics. We demonstrate the importance of antimony as a reactive surfactant and the proper usage of it with dilute nitrides in order to tailor the properties of solar cell and laser devices. The effects of the addition of antimony to low indium concentration 8% and low strain GaInNAs material for 1.0 eV solar cell applications were investigated. It was assumed previously that adding antimony helped all GaInNAs alloys, but the validity of this was not previously tested. The addition of antimony to high indium concentration 32% and high strain GaInNAs samples led to a dramatic improvement in optical quality and a widening of the growth window, while it led to a degradation in the low indium low strain composition samples. The addition of indium under constant antimony flux also improved the optical quality of the GaInNAs material. Variations in the indium and antimony compositions revealed a competition in atomic incorporation into the GaInNAsSb alloy. This interaction will be discussed. Increasing indium and/or strain confirmed the reactive surfactant properties of antimony on GaInNAsSb alloys. © 2006 American Institute of Physics.