Selective-area metal organic vapor phase epitaxy (SA-MOVPE) of InGaAsP-related semiconductors is one of the most important fabrication techniques for monolithically integrated optical devices. However, it has not been clarified how much the mask effect depends on the position of a wafer in a MOVPE reactor. Therefore, the uniformity of the mask effect in a reactor was investigated experimentally coupled with the simulation in both reactor scale and micrometer scale. As for the reactor-scale distributions of an InGaAsP layer, the measured profiles of the growth rate and composition were well-reproduced by the simulation that assumed the adsorption and the desorption of As and P species. As for the micro-scale distribution in the selective-area growth, the modulations of photoluminescence (PL) wavelength due to masks were dependent on the position of the substrate in the reactor. The reason was assumed to be that the surface reaction rate constant of a precursor had the distribution in the reactor, due to the concentration distribution of both precursors and reaction products. (c) 2006 Elsevier B.V. All rights reserved.