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Search for doped superconducting topological insulators is of prime importance for new quantum technologies. We report on fabrication of Sr-doped Bi 2 Te 3 single crystals. We found that Bridgman grown samples have p-type conductivity in the low 10 19 cm − 3 , high mobility of 4000 cm 2 V − 1 s − 1 , crystal structure independent on nominal dopant content, and no signs of superconductivity. We also studied molecular beam epitaxy grown Sr x Bi 2 − x Te 3 films on lattice matched (1 1 1) BaF 2 polar surface. Contrary to the bulk crystals thin films have n-type conductivity. Carrier concentration, mobility and c-lattice constant demonstrate pronounced dependence on Sr concentration x. Variation of the parameters did not lead to superconductivity. We revealed, that transport and structural parameters are governed by Sr dopants incorporation in randomly inserted Bi bilayers into the parent matrix. Thus, our data shed light on the structural position of dopant in Bi 2 Te 3 and should be helpful for further design of topological insulator-based superconductors. [ABSTRACT FROM AUTHOR]