In the current research, synthesis and deposition procedures of Bi2Se0.3Te2.7 and Bi2Te3 thin film materials using hydrothermal process and thermal evaporation method were developed. The effects of these procedures on microstructural, optical and thermoelectric properties of Bi2Te3 and Bi2Te2.7Se0.3 thin films were investigated. X-ray diffraction patterns confirmed the successful synthesis of the ternary and binary materials. However, the EDS analysis of the hydrothermally synthesized powders indicated a slight increase of Bi compared to the stoichiometric composition. In addition, SEM results showed that the Bi2Te3 thin film structure consists of smaller nano-sized grains and a great amount of micropores compared with that of Bi2Te2.7Se0.3 thin film. The thermoelectric results confirmed that the Se doping from 0 in Bi2Te3 to 0.3 in Bi2Se0.3Te2.7 thin film samples leads to an increase in the Seebeck coefficient from 60 to 125 µV/K and the carrier concentration from 1.4×1020 to 1.9×1020 at room temperature. The results showed that the optical and thermoelectric properties of Bi2Te3 based thin films were markedly improved by doping of Se in rhombohedral structure of Bi2Te3 using the hydrothermal method and thermal evaporation deposition approach. So that, the power factor and figure of merit increased from 0.018 to 0.3 and from 0.03 to 0.6, respectively at 25 °C.

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