Excitation Transfer through Quantum Dots Measured by Microluminescence: Dependence on the Quantum Dot Density

In this study, spatially resolved cw photoluminescence of self-assembled InAs quantum dots (QDs) on a GaAs matrix has been observed using the microluminescence surface scan technique. A sample containing QD densities from 0 up to 1600 dots/μm 2 was investigated. It was found that the QD density has a strong influence on the diffusion process and there is evidence of two different mechanisms operating at low and high QD concentration ranges that we interpret as photon recycling and interdot carrier tunneling, respectively.