InAs quantum dots (QDs) are grown on planar InP (1 0 0) by metalorganic vapor-phase epitaxy (MOVPE) with a thin GaAs interlayer beneath the QDs. The QDs' structural and optical properties are investigated when varying the GaAs interlayer thickness, growth temperature, and group V/III ratio and related to As/P exchange, the goal being to obtain high-quality QDs with emission wavelength around 1.55 mu m. (C) 2010 Elsevier B.V. All rights reserved.