Temperature dependence of hole mobility in GaAs-Ga_1-xAl _xAs heterojunctions

The mobility and carrier density of two-dimensional hole systems formed at the interface of GaAs-Ga_1-xAl_xAs heterojunctions have been measured in the temperature range 1.9-100 K. The mobility increased monotonically with decreasing temperature, and in one sample reached 2.35×10⁵ cm² V^-1 s ^-1, the highest value reported for holes. Optical phonon scattering (for T>40 K) and acoustic phonon scattering (for 15 K≤T≤40 K) are the mechanisms limiting the mobility down to low temperature, where Coulomb scattering dominates (for T<15 K). An observed linear increase of the inverse mobility with temperature cannot be explained quantitatively with a theory that was able to account for a similar behavior found in two-dimensional electrons.