Effect of nonradiative recombination centers on photoluminescence efficiency in quantum dot structures

The influence of dislocations on photoluminescence (PL) intensity in structures with InAs-GaAs quantum dots (QD) has been studied. The structural characteristics of samples were studied by transmission electron microscopy in bright-field and weak-beam dark-field diffraction conditions. At temperatures below room temperature and for moderate excitation density, the PL intensity in a structure containing large clusters with dislocations was about the same as in a structure with a significantly lower density of clusters. In contrast, the measurement of PL intensity at elevated temperatures and high excitation densities allows an accurate estimation of the structural perfection of QD structures. The overgrowth of QDs with a thin (1–2 nm) GaAs layer with subsequent annealing reduces the density of clusters with dislocations and significantly improves the temperature stability of the PL intensity.