Emission Variation of InAs Quantum Dots within (Al)GaInAs Quantum Wells in AlGaAs/GaAs Structures vs Quantum Well Compositions

Abstract

The parameters of quantum dots (QDs) of InAs inserted in Al0.30Ga0.70As/GaAs hetero structures with additional cap/buffer AlGaInAs quantum wells (QWs) of different compositions have been investigated by photoluminescence, transmission electron microscopy and high-resolution X-ray diffraction methods. QD structures with the buffer layers: In0.15Ga0.85As (#1) or In0.25Ga0.75As (#2) and covering (cap) layers: Al0.10In0.15Ga0.75As (#1) or Al0.40In0.15Ga0.45As (#2), are compared. Structure #1 is characterized by a higher density of QDs, high QD emission intensity and a smaller full width at half maximum of the PL bands, compared to #2. The dependence of the intensity of QD emission against temperatures of 10–500 K has been studied. Significant thermal quenching of the PL intensity was revealed in #1 compared to #2. HR-XRD investigation has confirmed that QD structures are of perfect crystalline quality with sharp QW interfaces and a high number of Pendellösung peaks were detected. To fit the HR-XRD scans, the X′Pert Epitaxy software has been applied. The peculiarities of the QD emission and the parameters of the HR-XRD scans are compared, as well as the advances of the QD structures studied are discussed.