Photoluminescence characterisation of InGaAs/GaAs quantum well structures

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Abstract
A photoluminescence (PL) study of InGaAs/GaAs strained quantum well (QW) structures is reported. Both fully strained and partially relaxed structures are examined, and the authors show that carrier localisation in the latter leads to enhanced extrinsic luminescence. Two other sources of localisation are considered, namely alloy and interface fluctuations, and their effect on the PL spectra is discussed. The effect of indium concentration (xIn) on the PL spectra is also examined, with greater surface roughening being observed at higher xIn, in turn leading to wider PL linewidths. Finally, they have examined the effect of nonradiative recombination in these QWS. In the unrelaxed layers the trap density is shown to be very low, while nonradiative recombination in the partially relaxed layers most likely occurs at electrically active extended dislocations.