On the kinetics of electron processes in $^{60}$Co $\gamma$-irradiated $n$-Ge single crystals

Variations in the main electrical parameters of $n$-Ge single crystals with different doping levels under the effect of $^{60}$Co $\gamma$-irradiation are investigated. A noticeable increase in the carrier mobility in the irradiated samples is observed in some dopant concentration range and the nature of this effect is explained. It is demonstrated that the electron-mobility variation under the action of $\gamma$-irradiation in the initial $n$-Ge crystals with an oxygen impurity and in the annealed crystals have opposite signs. It is established that the oxygen complexes formed in the samples during annealing and the local lattice stresses near these complexes play a key role in the radiation-induced mobility increase. It is clarified that the radiation resistance of the electron mobility significantly depends on the crystallographic orientation of the investigated samples.