A single layer of self-assembled InAs quantum dots was grown on a GaAs (001) substrate by gas source molecular-beam epitaxy. The quantum dots were overgrown with 65 nm GaAs, 25 nm InGaP, and a 10 nm GaAs etch-stop layer. This was either uncapped or capped with 100 nm of low-temperature (LT)-grown, lattice-matched InGaP (LT-InGaP) or with a SiO2 layer or Al2O3 layer. Photoluminescence (PL) measurements were made on samples before and after rapid thermal annealing at 550-900 degrees C and for 15-120 s at 650 degrees C. Samples capped with LT-InGaP showed a significant blueshift of the PL peak wavelength for anneals above 575 degrees C. By comparison, for the SiO2-capped and uncapped samples, the net blueshift only becomes significant for anneals > 700 degrees C, while an Al2O3 cap actually reduces the blueshift and suppresses the intermixing. It appears that the best conditions for spatially controlling the quantum dot intermixing occur with annealing at low temperatures (600-650 degrees C). (c) 2006 American Vacuum Society.