Time-resolved optical characterization of InGaAs/GaAs quantum dots

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Abstract
We report on the optical characterization of the strained InGaAs/GaAs quantum dots (QDs). The temperature dependence of the photoluminescence (PL) indicates that the onset energy of the thermal quenching in ∼20-nm-diam QDs is enhanced by a factor of ∼2 as compared to a quantum well (QW), due to the additional confinement. At low temperature, an increased carrier lifetime is observed for the QDs as compared to a reference QW (880 vs 330 ps). The carrier lifetime in the QDs was found to be independent of the temperature for T<30 K. In addition to this different dynamics of the localized excitons, we find that in the steady state PL and PL excitation, there is virtually no overlap between the emission and the absorption energies.