Electron mobility studies of the donor neutralization by atomic hydrogen in GaAs doped with silicon

Hall effect and conductivity measurements have been performed on n- and n+-silicon-doped GaAs epilayers before and after hydrogen plasma exposure. We show that the reduction of the free-carrier concentration in the hydrogen diffused region is accompanied by a significant increase of the electron mobility. This increase is mainly attributed to the transformation of the ionized silicon donors into neutral complexes. This result is in quite good agreement with the model of silicon donor neutralization by formation of neutral silicon–hydrogen complexes.