In this paper, InAs self-organized quantum dots (QDs) were deposited on (0 0 1)InP substrate with and without a GaAs interlayer by low pressure metalorganic chemical vapor deposition. An atomic force microscope image showed that InAs QDs arranged regularly on the GaAs interlayer. Comparison between photoluminescence (PL) spectra of InAs QDs with and without GaAs interlayer indicated that larger area density and much narrower size distribution of InAs QDs were obtained by inserting the GaAs interlayer. The area density of InAs QDs increased while the size distribution hardly changed when the thickness of InAs increased from 2.5 to 4 ML (monolayer). However, when the thickness of InAs increased to 6 ML, the mean size of InAs QDs increased while the area density of InAs QDs decreased because of the coalescence of QDs. PL spectra with different thickness of GaAs interlayer indicated that the largest density of InAs QDs could be obtained when the thickness of GaAs interlayer was 3 nm. (C) 2002 Elsevier Science B.V. All rights reserved.