A study on the influence of the growth conditions on the optical and structural properties of In0.6Ga0.4As quantum dots (QDs) grown on GaAs(I 0 0) substrates is presented. We investigated the impact of the substrate temperature, the growth rate, and V/III flux ratio on the full-width of half-maximum (FWHM) of the photoluminescence (PL) spectra and on the density and height of quantum dots. Our results show that the dot density depends strongly on the growth parameters. From them the substrate temperature has the strongest influence on the density and the height of QDs as well as on the PL properties. By varying only this parameter a direct control of the dot density and the height is possible over more than one order of magnitude (from 6 x 10(10)cm(-2) at 480 degrees C to 1 x 10(8) cm(-2) at 530 degrees C). The smallest PL linewidth of 36 meV was observed by QDs deposited at low substrate temperatures (480 degrees C). (C) 2008 Elsevier B.V. All rights reserved.