Spectroscopic signature of strain-induced quantum dots created by buried InAs quantum dots in an InGaAs quantum well

Abstract

Spectroscopic study of self-assembled InAs/GaAs quantum dots (QDs) capped with an InxGa1−xAs quantum well (QW) is carried out under variable excitation intensity and temperature. The QW reduces strain in the QDs, and it is demonstrated that the cap layer shifts the transition energy of the QD lower, while maintaining the strong quantization of the QD electronic states which develops in photoluminescence as a series of excited state transitions at higher excitation intensity. An additional spectral band is also revealed below the energy of the InGaAs QW exciton, which is unambiguously assigned to the emission of a strain-induced QD layer created by the InAs stressors within the InGaAs QW.