Carrier diffusion in the barrier enabling formation of charged excitons inInAs/GaAs quantum dots

It is demonstrated that the photoluminescence spectra of single self-assemb led quantum dots are very sensitive to the experimental conditions, such as excitation energy and crystal temperature. A qualitative explanation is gi ven in terms of the effective diffusion of the photogenerated carriers, det ermined by the experimental conditions, which influence the capture probabi lity and hence also the charge state of the quantum dots. This is proposed as a new tool to populate quantum dots with extra electrons in order to stu dy phenomena involving charged excitons.