We report the enhancement of electron mobility and power factor for 3D topological insulator Bi 2 Te 3 with Cobalt (Co) doping. Thermal variation of resistivity (ρ), thermopower (S), carrier concentration (n H ), magneto-resistance (MR), and magnetization measurements have been performed on synthesized Cobalt-doped n-type Bi 2 Te 3 , viz., Bi 2Àx Co x Te 3 (x = 0, 0.05, and 0.1) samples. Theoretical simulation of electrical and thermal transport parameters has been done in the frame of the Boltzmann equation approach and shows satisfactory agreement with experimental results. The thermoelectric performance, as estimated through power factor is found to increase with Co doping, with an enhancement of $47% is observed for Bi 1.9 Co 0.1 Te 3 sample. The positive linear MR and nearly cusp like behaviour at low field and low temperature confirms the presence of weak anti-localization (WAL) effects in pristine and Co-doped Bi 2 Te 3 samples. The field-dependent magnetization showing a cusp-like nature in the susceptibility data around zero field regions signifies the existence of topological surface state (TSS). MR along with magnetization data confirms the robustness of TSS with Co doping.

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