Emission and elastic strain in InAs dot-in-a well InGaAs/GaAs structures

The paper presents the photoluminescence (PL) study of InAs quantum dots (QDs) embedded in the asymmetric GaAs/In_xGa_1?xAs/In_0.15Ga_0.85As/GaAs quantum wells (QWs) with the different compositions of capping In_xGa_1?xAs layers. The composition of the buffer In_0.15Ga_0.85As layer was the same in all studied QD structures, but the In content (parameter x) in the capping In_xGa_1?xAs layers varied within the range 0.10–0.25. The In concentration (x) increase in the In_xGa_1?xAs capping layers is accompanied by the variation non-monotonously of InAs QD emission: PL intensity and peak positions. To understand the reasons of PL variation, the PL temperature dependences and X ray diffraction (XRD) have been investigated. It was revealed that the level of elastic deformation (elastic strain) and the Ga/In interdiffusion at the In_xGa_1?xAs/InAs QD interface are characterized by the non-monotonous dependences versus parameter x. The physical reasons for the non-monotonous variation of the elastic strains and PL parameters in studied QD structures have been discussed.