Investigation of InxGa1-xAs strain reducing layers effects on InAs/GaAs quantum dots

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Optical and morphological properties of self-assembled InAs quantum dots (QDs) covered by InxGa1-xAs strain reducing layers (SRL) with different thicknesses (2, 4, 6 and 8nm) and compositions (x=0.13, 0.18 and 0.30) were investigated. Photoluminescence from InAs QDs shows the dependence on indium mole fraction and thickness of the overgrown InxGa1-xAs SRL.Improvement in PL intensity and narrowing of PL width up to 26meV occurred together with a red shift of up to 138nm when the QDs were coved with 6nm of In0.18Ga0.82As. Also, we found that when the total amount of InAs deposited to form the QDs and the SRL was larger than a critical value of around 6MLs, the surface roughness increased and the PL intensity decreased drastically.