Carrier transport in self-organized InAs/GaAs quantum-dot structures studied by single-dot spectroscopy

A microphotoluminescence study of single InAs/GaAs quantum dots subjected to a lateral external electric field gives insight into carrier transport and capture processes into Stranski-Krastanov-grown quantum dots. The results obtained on the excitons in a single dot demonstrate a considerable luminescence intensity enhancement of the dot as well as a charge redistribution when an electric field is applied. The charge reconfiguration is evidenced by the transition from a predominantly negatively charged to a neutral charge state of the exciton. The model proposed to explain the charge redistribution is based on an effective hole localization at the potential fluctuations of the wetting layer.