Emission and elastic strain study in GaAs/In0.15Ga0.85As/InxGa1−xAs/GaAs quantum wells with embedded InAs quantum dots

GaAs/In0.15Ga0.85As/InxGa1−xAs/GaAs quantum wells (QWs) with embedded InAs quantum dots (QDs) and with variable In compositions in capping InxGa1−xAs layers (0.10 ≤ x ≤ 0.25) have been studied by means of photoluminescence, X ray diffraction (XRD) and high resolution XRD (HR-XRD) methods. InxGa1−xAs composition varying is accompanied by changing no monotonically the PL spectrum parameters of InAs QDs and by decreasing the InAs QD sizes. XRD and HR-XRD studies permit to control the InGaAs layer compositions and elastic strains in QWs. The analysis of HR-XRD results has shown that the level of elastic strain varies no monotonically in studied QD structures as well. The physical reasons of mentioned optical and structural effects and their dependences on capping layer compositions have been discussed.