Radiative Recombination Mechanisms of Large InAs/GaAs Quantum Dots

The optical properties of large InAs/GaAs quantum dots were investigated by low-temperature photoluminescence as a function of the excitation-power density. The presence of excited states was clearly detected below the saturation regime of the ground state. We analyzed the dependence of the integrated-photoluminescence intensity on the excitation-power density and the type of radiative recombination involving the electronic ground state and the excited states inside the quantum dots. We concluded that the probability to have more than one exciton by dots must be considered, and the usual equation , must be revised to correctly describe the origin of the recombination and must include other factors as scattering, relaxation time, radiative recombination rate, and others.