Inhibited Carrier Transfer in Ensembles of Quantum Dots

A report presents an experimental study of time-resolved, temperature-dependent photoluminescence in InxGa1–x As/GaAs specimens containing In0.6Ga0.4As quantum dots (QDs) distributed at several different areal densities on a GaAs surface and capped with GaAs. The specimens were fabricated by metal-organic vapor deposition of InxGa1–x As on slightly misoriented, semi-insulating GaAs(100) substrates. At high areal densities, the intensities of photoluminescence from the QDs were found to exhibit Arrhenius temperature dependence, attributed to thermal emission of charge carriers and recapture of the charge carriers into neighboring QDs. At low densities, it was found that the temperature dependence is more complex, the thermal transfer of charge carriers between neighboring QDs plays no significant role in the temperature dependence, and the efficiency of transfer of charge carriers into isolated QDs is limited by the rate of carrier transport in InxGa1–x As wetting layers.