We use photoluminescence (PL) to compare large low-density and small high-density self-assembled InAs/GaAs quantum dots (QDs)-capped at low and high temperatures. The low-temperature capped QDs show an improved PL linewidth of 23-26 meV, which is caused by an improvement of size and composition homogeneity of buried QDs due to suppressed material intermixing. The improvement is more pronounced for the small QDs. Excitation power and temperature-dependent PL are performed for all different QD types. (C) 2003 Elsevier Science B.V. All rights reserved.