Light-induced long-ranged disorder effect in ultra-dilute two-dimensional holes in GaAs heterojunction-insulated-gate field-effect-transistors

Comparing the results of transport measurements of strongly correlated two-dimensional holes in a GaAs heterojunction-insulated-gate field-effect-transistor obtained before and after a brief photo-illumination, the light-induced disorder is found to cause qualitative changes suggesting altered carrier states. For charge concentrations ranging from $3times10^{10}$ $cm^{-2}$ down to $7times10^{8}$ cm$^{-2}$, the post-illumination hole mobility exhibits a severe suppression for charge densities below $2times10^{10}$ cm$^{-2}$, while almost no change for densities above. The long-ranged nature of the disorder is identified. The temperature dependence of the conductivity is also drastically modified by the disorder reconfiguration from being nonactivated to activated.