Investigation of ionized impurity scattering in GaAs and InP using hydrostatic pressure

The application of hydrostatic pressure to change the effective mass of conduction electrons has been used to investigate the electron scattering mechanisms in GaAs and InP over a wide range of impurity concentrations. It is observed that the Hall mobility decreases with increasing pressure and that, unexpectedly the effect increases with increasing impurity concentration. Analysis shows that, for pure material, good agreement is obtained between theory and experiment. However, for increased carrier concentrations this agreement is lost, indicating the incomplete nature of the standard theories of ionized impurity scattering. The discrepancy is tentatively associated with scattering from fluctuations in the correlated distribution of the ionized impurities which are taken here to be Gaussian in shape.