Effect of temperature and rare-earth doping on charge-carrier mobility in indium-monoselenide crystals

In the temperature range $T$ = 77–600 K, the dependence of the charge-carrier mobility $(\mu)$ on the initial dark resistivity is experimentally investigated at 77 K $(\rho_{d0})$, as well as on the temperature and the level $(N)$ of rare-earth doping with such elements as gadolinium (Gd), holmium (Ho), and dysprosium (Dy) in $n$-type indium-monoselenide (InSe) crystals. It is established that the anomalous behavior of the dependences $\mu(T)$, $\mu(\rho_{d0})$, and $\mu(N)$ found from the viewpoint of the theory of charge-carrier mobility in crystalline semiconductors is related, first of all, to partial disorder in indium-monoselenide crystals and can be attributed to the presence of random drift barriers in the free energy bands.