We report improvement in the uniformity of InAs quantum dot (QD) arrangements grown on GaAs(100) surfaces by molecular beam epitaxy. GaAs surfaces were subjected to annealing processes at high temperature under no flux and under molecular Si flux for 10 s prior to InAs deposition. InAs thickness equivalent to 2.1 InAs monolayers (ML) was deposited on GaAs surfaces annealed under Si flux, giving a better QD arrangement with larger dimensions and lower density than that obtained for the InAs QDs grown conventionally. On the other hand, when InAs deposition took place on GaAs surfaces subjected to annealing under no As flux, two- to three-dimensional transition occurred at around 3.0 InAs ML, instead of at 1.7 ML as observed for conventional and Si-treated samples. Moreover, the QDs obtained by employing this high-temperature GaAs(100) substrate treatment demonstrated a significant reduction in size dispersion as well as considerable improvement in the uniformity of the spatial arrangement. Photoluminescence spectra revealed a redshift of the emission peak for the QDs grown on GaAs surfaces subjected to different annealing processes, as well as a reduction in the full width at half maximum of emission spectra. (C) 2004 American Vacuum Society.