Effect of Doping and Annealing on Thermoelectric Properties of Bismuth Telluride Thin Films

This work investigates the thermoelectric and electrical performance of nanostructured thin films of antimony (Sb)-doped Bi₂Te₃ (thickness ∼ 60 nm) and Bi_0.5Sb_1.5Te₃ (thickness ∼ 60 nm). The films were deposited on a glass substrate by thermal evaporation under high vacuum conditions. The structure and morphology of the films was investigated by standard characterization techniques. X-ray diffraction was used to identify the formation of different phases during the synthesis of the films. The Van der Pauw and Harman methods were employed to measure the conductivity (σ) and figure of merit (ZT). Further, samples were subjected to annealing under a high vacuum at 200°C for 1 h to improve the quality and ZT of the deposited films. The Sb-doped Bi₂Te₃ film was found to be ∼ 6.5 times more conductive than the Bi_0.5Sb_1.5Te₃ film. However, the two films exhibited comparable ZT values owing to the small value of the Seebeck coefficient (S) of Sb. This study represents a significant contribution in the field of thermoelectric materials and device applications.