The impact of confinement enhancement AlGaAs barrier on the optical and structural properties of InAs/InGaAs/GaAs submonolayer quantum dot heterostructures

The effect of additional AlXGa1−XAs barrier layer on luminescence and structural behaviors of four cycle InAs/In0.15Ga0.85As/GaAs based quantum dots (i.e., standard submonolayer (SML) QDs) has been investigated here. Blue-shift in peak emission wavelength, along with narrow full width at half maxima (FWHM) is observed, as evidenced by the photoluminescence measurement results. InAs SML QDs in an In0.15Ga0.85As/GaAs well with a confinement enhancing Al0.2Ga0.8As barrier exhibits the lowest FWHM of 10.12 meV with an activation energy of 110 meV. Cross-sectional transmission electron microscopy confirms improvement in QD size distribution and the presence of small QDs of high crystalline quality. Symmetric rocking curves along the [004] Bragg angle affirm that incorporation of the additional barrier improvs the crystalline quality of corresponding heterostructures and yields sharp interfaces with adequate amount of QDs. In addition, the ex situ annealing study exhibits the enhancement in thermal stability of optical properties through integration of this symmetric AlGaAs barrier.