Carrier screening effects in semimetallic InAs single-quantum wells

Measurements of the resistivity between 40 mK and 1 K are presented for electron-hole systems comprised of InAs single-quantum wells clad with ${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Al}}_{\mathrm{x}}$Sb for x=0, 0.15, and 0.30. In contrast to previous studies, no logarithmically increasing resistivity with decreasing temperature is observed, and for samples with hole carriers we find a weakly decreasing resistivity. Measurements of the low-field magnetotransport, as well as the resistivity at higher temperatures, inidicate that the decreasing resistivity is related to an increasing electron mobility due to the presence of hole carriers, and that in the low-temperature limit the electrons are scattered primarily by holes and impurity charges located at the interface.