(GaIn)(NAs) can be grown pseudomorphically strained on GaAs with a very small band gap, opening up the possibility of achieving 1.3 or even 1.55 mum emission; however, wavelengths are actually limited by the N solubility limit and the high In strain limit. By adding Sb to the quaternary (GaIn)(NAs) we have observed a remarkable shift towards longer luminescent wavelengths, while maintaining good crystal quality. The growth of this now five-component system poses several challenges in regards to the epitaxial growth and the compositional characterization. The present paper elucidates the role of Sb as an alloy constituent as well as a surfactant in the growth of this pentanary alloy. The compositional changes of the material resulting from the addition of Sb will be shown. (C) 2002 Elsevier Science B.V. All rights reserved.