We investigated the effect of the post growth interruption (Cl) on InAs quantum dots (QDs) grown on InxGa1 - xAs strained buffer layers (SBL). When QDs were grown on the 5 and 10% In content SBLs by using post Cl, the size of QDs increased as its density decreased. Based on the 50 meV red-shift of PL in these cases, the transport of materials between QDs leads to the increase of QD size with maintaining its composition during the post GI. On the other hand, when using SBLs with the 15 and 20% In contents, the size of QDs increased, but its density was a little reduced. In addition, PL results were observed blue-shifted by about 20 meV and 2 meV, respectively. Considering the interruption of source gases during the post GI, these observations are strong evidence of the Ga incorporation from 15 and 20% In content SBLs. Therefore, these results imply that the dominant mechanism which increases the size of QDs during the post GI depends on the growth condition of SBL. (c) 2010 Elsevier B.V. All rights reserved.