Potential barrier study at the InGaAs/InAs quantum dot interface in asymmetric multi quantum well structures

The photoluminescence and its temperature dependences have been investigated for the InAs quantum dots embedded in the asymmetric GaAs/InxGa1−xAs/In0.15Ga0.85As/GaAs quantum wells (dot-in-a-well, DWELL structures) as a function of the In content x (x = 0.10–0.25) in the capping InxGa1−xAs layer. The study of PL temperature dependences in the range of 80–120 K has revealed the potential barrier for electrons at the capping InxGa1−xAs/InAs QD interface. The value of mentioned barrier has varied in QD structures with the different InxGa1−xAs capping layer compositions and it was estimated in the studied asymmetric GaAs/InxGa1−xAs/In0.15Ga0.85As/GaAs DWELL structures. It is shown that the barrier for electrons equal to 48 and 24 meV appears in the InGaAs conduction band at the formation of InGaAs QW/InAs QD interface for the In compositions of x = 0.10 and 0.15, respectively. This barrier has not been detected in DWELLs with the In compositions x = 0.20 and 0.25. The energy gap offsets at the InAs/InxGa1−xAs interface in studied structures has been estimated and discussed as well.