Abnormal photoluminescence behavior of self-assembled InAs quantum dots with bimodal size distribution

We report on the abnormal behaviors of the optical properties for self-assembled InAs/GaAs quantum dots (QDs) by using excitation-intensity-dependent and temperature-dependent photoluminescence (PL) spectroscopy, The excitation intensity- and temperature-dependent PL of InAs QDs indicate that the double-peak feature is due to ground-state transitions of QDs with branches of two different sizes, From the variations in the PL peak position and linewidth with temperature, thermally activated carriers transfer from the small QDs to large ones, and that carrier transfer between QDs can be facilitated by using a wetting layer.