Photoluminescence (PL) and its temperature dependence have been investigated in InAs quantum dots (QDs) embedded in In0.15Ga0.85As/GaAs quantum wells (QWs). The QD density varied from 1.1 X 10(11) down to 1.3 X 10(10) cm(-2) with an increase in QD growth temperature. Three stages have been revealed in the thermal decay of the PL intensity in InAs QDs. A variety of activation energies of PL thermal decay are discussed. Numerical simulations of experimental PL thermal decay curves give possibility to analyze the area of localization of nonradiative defects in InGaAs/GaAs QW structures with different InAs QD densities. (C) 2009 American Vacuum Society. [DOI: 10.1116/1.3010718]