Abstract
Binding energy of donors in high quality epitaxial GaAs is investigated as a function of the magnetic field between 0 and 12 T. Transverse magnetoresistance and the Hall effect are used as experimental tools. The samples are characterized using temperature dependence of free electron density and mobility, taking consistently into account the Hall scattering factor and the effective conduction depth of the structure. Our analysis of the data at the freeze-out regime of higher magnetic fields allows for the hopping conductivity over donor states. The determined magnetodonor energies are about 1 meV lower than the theoretical ones, which represents a very large improvement in comparison with previous studies.