Hopping conduction and magnetoresistance of a GaAs/Al_xGa _1-xAs quantum well with embedded InAs dots

Magnetoresistance and temperature-dependent conductance are measured in the sample made of a GaAs/Al_xGa_1-xAs quantum well with self-assembled InAs dots. Conductance is analyzed by Mott's hopping theory; the localization lengths have been extracted at various gate voltages. The sample is in the transition from near to metal-insulator to the deeply hopping regime with the combined effect of the long- and short-range scattering potentials. The magnitude of the negative magnetoresistance increases with increasing negative gate voltage. The magnetic-field dependence of the resistance can be explained by the theory of the interference model of hopping electrons.