Diffusion process of excitons in the wetting layer and their trapping by quantum dots in sparsely spaced InAs quantum dot systems

Photoluminescence (PL) characteristics have been systematically studied in a set of novel InAs quantum dot (QD) systems, where the average interdot distance is set in the range between 2 and 20 μm by controlling the self-assembled growth on GaAs. By investigating the ratio of the PL intensity of QDs to that of the wetting layer (WL), the diffusion of excitons in the WL and their subsequent trapping by QDs are examined. It is found that the diffusion length LD of excitons is about 0.45 μm at 11 K, but increases with temperature, reaching 4 μm at 60 K.