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 ($p\gtrsim 4\times {10}^9{\mathrm{cm}}^{-2}$), the nonmonotonic temperature dependence ($\sim 50–300\mathrm{mK}$) of the resistivity is consistent with temperature dependent screening of residual impurities. At a fixed temperature of $T=50\mathrm{mK}$, the conductivity versus density data indicate an inhomogeneity driven percolation-type transition to an insulating state at a critical density of $3.8\times {10}^9{\mathrm{cm}}^{-2}$.

• Received 30 April 2007

DOI:https://doi.org/10.1103/PhysRevLett.99.236402