The dependence of the size and the strain in the double-stacked InAs/GaAs quantum dot (QD) was investigated by using the reflection high-energy electron diffraction pattern, transmission election microscopy (TEM), high-resolution X-ray diffraction (HRXRD), and photoluminescence (PL) measurements. The results of the TEM images and the reciprocal spacer mapping, obtained from the HRXRD measurements, showed that the microstructures of the InAs QDs were significantly affected by the strain-controlled InAs layer thickness, and the PL spectra showed that the peak intensity and position corresponding to the interband transitions from the ground electronic subband to the ground heavy-hole band of the InAs QDs strongly depended on the thickness of the InAs layer embedded in the GaAs barrier. The present results can help improve the precise control of the size and the density in the InAs/GaAs multiple-stacked QD arrays. (c) 2005 Elsevier B.V. All rights reserved.