Temperature dependence of exciton-capture at impurities in GaAs/AlxGa(1-x) As quantum wells
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چکیده
In this paper we present an investigation of the exciton capture process in GaAs/Al.jGa.7A.s quantum wells using a picosecond time-resolved photoluminescence technique. We demonstrate that there are significant differences in the capture mechanism for narrow quantum wells in comparison to bulk material. In particular the initial capture efficiency is shown to increase with temperature. This behaviour is understood in terms of the role of localisation of the free exciton in the potentials caused by the interface roughness. Higher temperam destroy this localkation process which otherwise limits the total capture rate for the exciton to the impurityThe effect of localisation on capture is also shown to be stronger for narrower wells. We conclude that the relative weakness of bound exciton recombination in the near bandgap luminescence of doped quantum wells can in part be understood by the reduction of capture efficiency due to localisation.
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تاریخ انتشار 2016