Carrier localization effects in energy up conversion at ordered (Al0.5Ga0.5)0.5In0.5P/GaAs heterointerface

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Abstract
We investigated up-converted photoluminescence (UPL) in long-range ordered (Al 0.5 Ga 0.5 ) 0.5 In 0.5 P grown on GaAs (115) A and GaAs (001). A multidomain structure of the ordered epitaxial film, each domain having its own order parameter, causes a band gap fluctuation. This enhances a localization of excited carriers from the GaAs layer. The UPL intensity excited at 1.83 eV depends nonlinearly on the excitation-laser power. It was found that an excitation-power dependence of the normal PL intensity excited by an above-gap light (2.54 eV) agrees well with those of the UPL at 11 K. However, at elevated temperatures, the excitation-power dependence of the normal PL intensity becomes linear. These results suggest that the nonlinear dependencies of the UPL intensity at low temperature closely relate to localization properties of photoexcited carriers. Furthermore, we observed band-filling effects on UPL under an irradiation of the above-gap light.