Self-organized InAs quantum dots (QDs) with different depositions grown on an InP (100) substrate were prepared by solid source molecular beam epitaxy at different temperatures. Photoluminescence (PL) measurements are used to investigate optical properties of the QDs. It is observed that the PL emissions of QDs with 10 Å InAs deposition exhibit multiple peaks. Besides emission from the QDs at lower energy, two or three additional peaks are observed. This behavior is attributed to wetting layers with various thicknesses caused by an As/P exchange reaction, and this reaction is enhanced by an increase of the growth temperature. The features of PL emission change dramatically for the samples with increased InAs deposition. The PL emission from the QDs decomposes into two Gaussian peaks, which are associated with emission from QDs with two different size distributions. Atomic force microscopy examination shows the bimodal size distribution branch. This observation of the QD size distribution is simply explained by the surface mass transfer. © 2001 American Vacuum Society.