Temperature and excitation density dependence of the photoluminescence from annealed InAs/GaAs quantum dots

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Using rapid thermal annealing, we fabricated a series of InAs/GaAs quantum dot samples with ground-state emission ranging from 1.05 eV to 1.35 eV. This set of annealed samples, all having the same density, allows us to study the influence of the barrier height on the temperature dependence of the photoluminescence (PL). The integrated PL follows an Arrhenius-type behavior, with activation energies matching the barrier heights. However, the quenching occurs at lower temperatures as the barrier height decreases. The modeling of these data enables us to understand the important mechanisms determining the critical temperature where the quenching occurs. We also present a detailed investigation into the excitation density dependence of the photoluminescence at different temperatures. Under relatively low excitation, this dependence is linear at 10 K, and becomes increasingly superlinear and eventually quadratic as the temperature is increased and carriers escape from the dots. However, under high excitation, the dependence remains linear even at high temperatures and the activation energy for quenching is different. We show that all these results can be understood by considering the independent capture and escape of electrons and holes in the dots.