Fabrication of induced two-dimensional hole systems on (311)A GaAs

We demonstrate a method for fabricating induced two-dimensional hole devices in (311)A GaAs. The method uses a metallic p(+)-GaAs capping layer as an in situ top gate that pins the Fermi energy close to the valence band, thereby allowing very small gate biases to be used to induce a two-dimensional hole system at a AlGaAs/GaAs interface. We present transport data from devices with different levels of background impurities. Modeling the mobility as a function of hole density gives a quantitative measure of the level of disorder and indicates that these systems can be used for a systematic study of the effects of disorder in strongly interacting low-dimensional systems. (c) 2006 American Institute of Physics.