Effects of thickness on thermoelectric properties of Bi_0.5Sb_1.5Te₃ thin films

Bi₂Te₃-based materials have been widely utilized for commercial bulk thermoelectric (TE) devices. For the manufacture of miniaturized TE devices, the large-scale deposition of high-performance Bi₂Te₃-based thin films is crucial. However, it has not yet been effectively resolved. Herein, the Bi_0.5Sb_1.5Te₃ films with different thicknesses were grown on sapphire substrates by controlling the co-sputtering time. We reveal that the film thickness has a significant impact on the electrical transport properties. Due to the mutual influence of electrical conductivity and Seebeck coefficient, there exists an optimal thickness with the maximum power factor is as high as 2900 μW m⁻¹ K⁻². Therefore, systematic research on the thickness-dependent TE characteristics of Bi₂Te₃-based films and the deposition of high-performance films will provide important information for the large-scale development of high-performance micro-TE devices.