Results of a post-growth rapid thermal annealing (RTA) on GaAs proximity-capped structures with high density (-10(11) cm(-2)) of self-assembled InAs/GaAs quantum dots (QDs) are presented. Features due to the QDs, bi-dimensional platelets (2DP) and InAs wetting layer (WL) were identified in photoluminescence (PL) spectrum of the as-grown sample. It is shown, using transmission electron microscopy, that RTA at temperature up to 700 degreesC (for 30 s) results in an increase of QDs lateral sizes. After RTA at 800 degreesC or higher temperatures, no QDs can be distinguished and substantial thickening of the WL can be seen. The main PL peak blueshifts as a result of RTA in all investigated temperature ranges, which is accompanied by a quenching of the 2DP and WL PL. It is proposed that the main PL peak, which is due to the QDs in the as-grown sample, results from optical recombination in the modified WL in the samples, after RTA at 800 degreesC and higher temperatures. Laterally-enhanced Ga/In interdiffusion induced by strain is proposed to explain a relatively fast dissolution of QDs.