Enhanced electron-electron interactions in GaAs layers doped with high concentrations of donor and acceptor impurities

Magneto-transport properties of Si- and Be-doped GaAs layers grown by molecular-beam epitaxy at low temperatures were studied in order to observe effects of electron-electron interactions enhanced by doping high concentrations of donor and acceptor impurities. The negative magneto-resistance was observed from n-type samples in the whole measured temperature range up to room temperature. Magneto-conductance curves above 150 K are in close accord with calculations based on the localization theory, while those below 150 K at high magnetic fields are explained with the theory of electron-electron interactions. The temperature-dependence of the inelastic scattering time which was derived from the magneto-conductance curves suggests that it is determined by electron-electron collisions at temperatures below 150 K. Results of samples with different impurity concentrations show that doping of higher impurity concentrations along with lower carrier concentrations leads to the significant enhancement of electron-electron interactions. The effect of the spin-orbit interaction on the magneto-conductance was also observed at low magnetic fields.