Resistivity of a high mobility two-dimensional hole gas on (100) GaAs in the vicinity of the metal-to-insulator transition

We report on the density and temperature dependence of the resistivity of an extremely high mobility, carbon-doped, two-dimensional hole system (2DHS) in the vicinity of the putative metal-to-insulator (MIT) transition. The high mobility of our structures allows us to probe the conduction properties at very low 2D densities, $\sim $10$^{9}$cm$^{-2}$, a regime in which interactions are expected to play an important role. Using a back-gated structure, a mobility of 2.2x10$^{6}$cm$^{2}$/Vs is achieved at a density of 2.9x10$^{10}$cm$^{-2}$ at T=50mK. Backgating allows us to monitor the evolution of the resistivity as the density is continuously tuned from 2.9x10$^{10}$cm$^{-2}$ to 2.9x10$^{9}$cm$^{-2}$. From analysis of the temperature dependence of the resistivity, the sample becomes insulating at 3.5x10$^{9}$cm$^{-2}$. We compare our data to existing models of the MIT in high mobility, low density, structures.