An optical study of the lateral motion of two-dimensional electron-hole pairs in GaAs/AlGaAs quantum wells

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Abstract
The authors have studied the lateral transport of electron-hole (e-h) pairs in GaAs/AlxGa1-xAs quantum wells (QWS) (0.3<or=x<or=1.0) as a function of well width, temperature and Al content in the barriers by a method based on transparent circular microstructured areas in otherwise opaque masks. In the experiment they observe an increase of the e-h-pair mobilities with both growing Al content and increasing well width. The experimental results are compared with theoretical model calculations for different scattering mechanisms such as acoustic-deformation-potential (AC), polar-optical (PO), barrier-alloy-disorder (BAL), impurity and interface-roughness (IR) scattering. For low temperatures (about 40 K<T100 K AC scattering and PO scattering are found to dominate the scattering processes. In addition, a crossing of the theoretical electron and hole mobilities is observed for isolated BAL scattering for very narrow well widths or very low Al contents.