The structural modification of InAs/GaAs(0 0 1) quantum dots (QDs) grown with 2.0 or 2.7 monolayers (ML) of InAs during annealing was investigated by a combination of in situ X-ray diffraction (XRD), reflection high-energy electron-beam diffraction (RHEED) and ex situ atomic force microscopy (AFM). For 2.0 ML in coverage, QD size increased due to the incorporation of Ga atoms into the QDs, after which QD ripening occurred. For 2.7 ML in coverage, on the other hand, the change in the strain energy due to enhanced intermixing of In and Ga atoms induced a morphological transition from three dimension (3D) to two dimension (2D). These results yielded some useful information about control of the SK QD structure during growth interruption. (c) 2006 Elsevier B.V. All rights reserved.