Optical Properties and HR-XRD Study of /InGaAs/Al Ga As/GaAs Structures with InAs Quantum Dots and Different Capping Layers

Abstract

The Al0.30Ga0.70As/InGaAs/AlGaInAs/Al0.30Ga0.70As structures with embedded InAs quantum dots (QDs) covered by strain reduced AlGaInAs capping layer have been investigated in as grown state by means of a photoluminescence (PL) and high resolution X ray diffraction (HR-XRD) methods. Two types of QD structures with different quantum well (QW) capping layers: Al0.10In0.15Ga0.75As (#1) and Al0.40In0 .15Ga0.45As (#2) are compared. It is revealed that the QD emission in the structure with Al0.10In0.15Ga0.75As capping is characterized by the highest PL intensity of the ground state (GS) band and smaller the full with at half maximum (FWHM), compared to #2 structures. The variation of the GS emission peak versus temperature has been monitored within the range of 10-400K for the as grown film states and compared with shrinkage of the energy bandgaps in the InAs and GaAs bulk crystals. The results show that the efficiency of Ga/Al/In intermixing in #2 is less than in #1. HR-XRD study has shown that the both QD structures are characterized by best quality of QW interfaces with the high numbers of Pendellösung peaks. The HR-XRD scans were numerically modelled for the analysis of QW layer compositions. The peculiarities of PL spectra of the studied QD structures are analyzed and the advances of studied QD structures have been discussed.