Abstract
We present the analysis of magnetotransport measurements of n-type GaAs samples grown by MBE technique. The samples cover a wide range of donor concentrations, from 4.0 x 10(14) cm(-3) to 3.0 x 10(16) cm(-3). Experiments were performed for a wide range of temperatures and magnetic fields. The apparition of a magnetic freeze-out for conduction electrons allows us to extract the binding energy of donors as a function of the magnetic field as well as the impurity concentration. The measured binding energies decrease as the doping level increases. This behavior is due to the overlap of the wavefunctions of neighbouring impurities which results in the formation of an impurity band. (c) 2005 WILEY-VCH Verlag GmbH W Co. KGaA, Weinheim.