Spatial variations of photoluminescence line broadening around oval defects in GaAs/AlGaAs multiple quantum wells

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Abstract
The authors have investigated spatially resolved photoluminescence spectra around several alpha - and lambda -type oval defects in GaAs/AlGaAs multiple-quantum-well structures. In their low-temperature photoluminescence set-up they combine a high spectral resolution with a 2 mu m spot size on the sample. In the alpha -type defects the authors observe a 25-45 meV low-energy tail of the main quantum well recombination peak near the core of the oval defect as well as an approximately 1 meV line broadening originating from two regions which are symmetrically located at either side of the (110) symmetry axis of the defect. These line-broadening effects are explained by vertical growth rate variations within the oval defect.