Photoluminescence wavelength emission of GaxIn1-xAsyP1-y/InP heterostructures grown in multiwafer gas-source molecular-beam epitaxy (GSMBE) is studied in detail for both bulk and multiple quantum well (MQWs) heterostructures. Excellent photoluminescence wavelength uniformity is reported in 4 x 2-in. configuration, demonstrating the compatibility of GSMBE process with large-scale 1.55 mu m telecom laser production. A strong dependence of wavelength uniformity on group-V/group-III flux ratio is reported and analyzed quantitatively. An empirical model based on the interplay between group-V elements incorporation and gas distribution is proposed to predict the influence of AsH3 and PH3 fluxes on As content in the solid. This understanding opens the way to an accurate tuning of wavelength dispersion of GaxIn1-xAsyP1-y/InP MQWs grown in multiwafer GSMBE,system. (c) 2004 Elsevier B.V. All rights reserved.