Compositional uniformity of lattice-matched qaternary (InGaAsP) epitaxial layers on InP substrate was examined with multi-wafer MOVPE growth. Epitaxial layers with the photoluminescence (PL) wavelength of 1.3 mum were obtained with compositional uniformity standard deviation of 0.80 nm in all four wafers, and 0.97 nm in all six wafers for the same growth batch. The vertical high-speed rotating-disk reactor was used to grow the epitaxial layers on four or six 2" InP wafers for the same growth batch. Compositional uniformity depends on wafer temperature that attributes to the thermal contact resistance between a wafer and a wafer carrier. It is important to suppress the temperature difference between them. The structure of the wafer carrier was optimized by computational fluid dynamics (CFD) analysis in order to compensate the thermal contact resistance. The wafer carrier temperature was successfully controlled to the same as the wafer, so that compositional uniformity of epitaxial layers was improved. (C) 2004 Elsevier B.V. All rights reserved.