OBSERVATION OF THE EFFECT OF ELECTRON-ELECTRON SCATTERING ON THE IMPURITY-LIMITED RESISTIVITY OF A 2-DIMENSIONAL ELECTRON-GAS

We have investigated the low-temperature resistivity of a two-dimensional electron gas (2DEG) formed at a GaAs/AlxGa1-xAs heterojunction (a) as a function of electron temperature by heating the 2DEG with a dc current and (b) as a function of lattice temperature. In both cases, we find that the resistance initially decreases with increasing temperature due to ionized impurity scattering, but then passes through a minimum at a temperature of around 10 K. We show that at this temperature the ionized impurity and electron-electron- scattering lengths become equal in magnitude, with the result that the usual negative temperature dependence of the ionized impurity resistivity is reversed. The effect is due to the randomization of electron energy through electron-electron scattering between impurity scattering events. © 1995 The American Physical Society.