Intersubband scattering in GaAs/AlxGa1-xAs heterostructures

We present measurements of both transport and quantum mobility in a GaAs/AlGaAs heterostructure as a function of the electron concentration, in a range where the second subband becomes occupied. From these measurements we observe a drop in the mobilities at the onset of the second subband. The second subband influences the electrical transport properties by intersubband scattering and screening effects. The individual contribution of these effects determines the height and sign of the step in the mobility and depends on the spatial overlap between the wavefunctions of both subbands, as we show with theoretical model calculations