Fabrication and characterisation of ambipolar devices on an undoped   AlGaAs/GaAs heterostructure
  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. 
J. C. H. Chen, D. Q. Wang, O. Klochan, A. P. Micolich, K. Das Gupta,   F. Sfigakis, D. A. Ritchie, D. Reuter, A. D. Wieck, a...
cond-mat.mes-hall