  We have fabricated AlGaAs/GaAs heterostructure devices in which the
conduction channel can be populated with either electrons or holes simply by
changing the polarity of a gate bias. The heterostructures are entirely
undoped, and carriers are instead induced electrostatically. We use these
devices to perform a direct comparison of the scattering mechanisms of
two-dimensional (2D) electrons
($\mu_\textrm{peak}=4\times10^6\textrm{cm}^2/\textrm{Vs}$) and holes
($\mu_\textrm{peak}=0.8\times10^6\textrm{cm}^2/\textrm{Vs}$) in the same
conduction channel with nominally identical disorder potentials. We find
significant discrepancies between electron and hole scattering, with the hole
mobility being considerably lower than expected from simple theory.
