Post-growth intermixing by rapid thermal annealing in self-assembled InAs/InP quantum dot (QD) structures with and without SiO2 capping has been investigated. Room-temperature photoluminescence spectra measured from the intermixed QD structures show substantial blue shift accompanied by an increase in the PL intensity. Such group V intermixing is further probed by micro-Raman scattering technique. Apart from InAs and InP related longitudinal optical and transverse optical phonon peaks, Raman spectra show the appearance of InAs- and InP-like phonon peaks from InAsP-like alloy formed at the QD interfaces. These alloy modes show substantial peak shift with respect to annealing temperature and clearly indicates As/P exchange at the QD interfaces. (c) 2005 The Electrochemical Society.