Influence of spatial doping correlation on scattering times studied in gated and ungated GaAs/AlGaAs quantum weels under hydrostatic pressure

Silicon modulation delta -doped GaAs/AlGaAs quantum wells were investigated by Hall effect and Shubnikov de Haas measurements. The two-dimensional carrier concentration ns was either changed with applied gate voltage or by application of hydrostatic pressure. Due to cooling under different gate voltages or hydrostatic pressures, the correlation between the charged donors could be changed and investigated by evaluation of the transport mobility mu 1 and quantum mobility mu q. At the occupation of the second subband, the two mobilities mu 1 and mu q behave qualitatively different. The experimental results are compared with calculations of the scattering times and show the influence of correlation effects on mobility.