OPTICAL-PROPERTIES OF GAAS/ALGAAS QUANTUM DOTS REALIZED BY IMPLANTATION-INDUCED INTERMIXING

GaAs/AlGaAs quantum dots with diameter down to 70 nm have been realized by implantation induced intermixing. Photoluminescence studies demonstrate a high optical quality. From the systematic small blue shift of the dot luminescence with dot diameter it is shown that the dots reveal a steep radial potential and that the blue shift is caused by quantization. The increase of relative quantum efficiency of the dots with decreasing diameter can be explained by a model which takes the graded shape of the potential and the carrier capture from the barrier into account. Time-resolved measurement yield short carrier lifetimes in the dots. With decreasing dot diameter an increasing decay time and a slowed carrier cooling is observed.