Lattice-matched, single and multiple InGaP/GaAs/InGaP quantum wells (QWs) were grown at 600 degreesC by low-pressure metalorganic vapour phase epitaxy (LP-MOVPE), with the use of the tertiarybuthylarsine (TBAs) and tertiarybuthylphosphine (TBP) group-V sources. In order to enhance the interface abruptness, different gas switching sequences were exploited during the growth of the interface, and the best results were obtained by inserting a few monolayer-thick GaAsP interlayers (IL), at the direct GaAs-on-InGaP interface. Low-temperature photoluminescence (PL), high resolution X-ray diffraction, transmission electron microscopy and photoreflectance spectroscopy analysis were performed on the grown heterostructures, to correlate the adopted growth sequence with the interface properties and the QW optical transitions. Promising results were obtained, among which: (a) the suppression of the anomalous PL emission at low energy, (b) optical emission from the InGaP/GaAs/InGaP QWs, exhibiting a good correlation with theoretical expectations, (c) direct interface fluctuations within 1 nm. (C) 2003 Elsevier B.V. All rights reserved.