The carrier-transport characteristics of the low and high surface density InAs/GaAs quantum-dot (QD) heterosystems are studied in depth using photoluminescence measurements. It is found that both the anomalous temperature- and photoexcitation-dependent phenomena can be attributed to the carrier-thermalization processes. Photogenerated carrier redistribution leads not only to linewidth broadening but also to emission blueshifts for the radiative transitions in QD ensembles under various pump intensities. The short dot distance of a high dot-density system facilitates thermally excited carrier redistribution. However, due to the inhibition of photocarrier transfers, QD heterostructures that have a long interdot spacing exhibit more excitation insensitivity. (c) 2006 American Vacuum Society.