Nonmonotonic Temperature-Dependent Resistance in Low Density 2D Hole Gases

The low temperature longitudinal resistance-per-square R sub (xx) (T) in ungated GaAs/Al sub x Ga sub (1-x) As quantum wells of high peak hole mobility 1.7x10 sup 6 cm sup 2 V sup (-1) s sup (-1) is metallic for 2D hole density p as low as 3.8x10 sup 9 cm sup (-2). The electronic contribution to the resistance R sub (e1) (T), is a nonmonotonic function of T, exhibiting thermal activation, R sub (e1) (T) alphs exp {-E sub a/kT}, for kTE sub F. The form of R sub (e1) (TO is independent of density, indicating a fundamental relationship between the low and high T scattering mechanisms in the metallic state.