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

TL;DR

This study investigates how temperature and density affect resistivity in a high-quality two-dimensional hole system on GaAs, revealing a percolation transition to an insulator at low density and temperature-dependent screening effects.

Contribution

It provides new insights into the transport and percolation behavior of low-density, high-mobility 2D hole systems, highlighting a critical density for the insulator transition.

Findings

Resistivity shows nonmonotonic temperature dependence due to screening.

Percolation transition occurs at a critical density of 3.8×10^9 cm^-2.

Conductivity data indicates an inhomogeneity-driven transition.

Abstract

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