Effects of interactions and disorder on the compressibility of two-dimensional electron and hole systems

The compressibility χ of dilute two-dimensional electron and hole gases in GaAs semiconductor structures has been studied in the ranges of the interaction parameter rs=1–2.5 and rs=10–30 for the electron and hole system, respectively. Nonmonotonic dependence of χ-1 with an upturn at low carrier densities is observed. Despite the large difference in rs the behavior of χ-1 in both systems can be accurately described by the theory of nonlinear screening of disorder by the carriers.