Transport and percolation in a low-density high-mobility two-dimensional hole system

We present a study of the temperature and density dependence of the resistivity of an extremely high quality two-dimensional hole system grown on the (100) surface of GaAs. For high densities in the metallic regime (p 4×109cm-2), the nonmonotonic temperature dependence (∼50-300mK) of the resistivity is consistent with temperature dependent screening of residual impurities. At a fixed temperature of T=50mK, the conductivity versus density data indicate an inhomogeneity driven percolation-type transition to an insulating state at a critical density of 3.8×109cm-2.