Effect of thallium doping on the mobility of electrons in Bi$_{2}$Se$_{3}$ and holes in Sb$_{2}$Te$_{3}$

The Shubnikov–de Haas effect and the Hall effect in $n$-Bi$_{2-x}$Tl$_{x}$Se$_{3}$ ($x$ = 0, 0.01, 0.02, 0.04) and $p$-Sb$_{2-x}$Tl$_{x}$Te$_{3}$ ($x$ = 0, 0.005, 0.015, 0.05) single crystals are studied. The carrier mobilities and their changes upon Tl doping are calculated by the Fourier spectra of oscillations. It is found shown that Tl doping decreases the electron concentration in $n$-Bi$_{2-x}$Tl$_{x}$Se$_{3}$ and increases the electron mobility. In $p$-Sb$_{2-x}$Tl$_{x}$Te$_{3}$, both the hole concentration and mobility decrease upon Tl doping. The change in the crystal defect concentration, which leads to these effects, is discussed.