Structural and electrical properties of flash evaporated (Bi0.4Sb0.6)2Te3 alloy thin films

The alloys of (Bi_1-xSb_x)₂Te₃ are the best materials currently available for thermoelectric application near room temperature. Thin films of (Bi_0.4Sb_0.6)₂Te₃ alloy were prepared by flash evaporation technique onto clean glass substrates held at room temperature in a vacuum of 1×10^-5 torr. Thickness of the films was monitored by a quartz crystal thickness monitor. Structural characterisation was carried out by X-ray diffraction (XRD) and transmission electron microscopy (TEM). It was found that the structure of the alloy films is hexagonal and the films are polycrystalline. Electrical resistivity and thermoelectric measurements were carried out on these films in the temperature range 300 K to 450 K. From the electrical resistivity measurements, the plot of Ln(σ) vs. 1000/T was drawn. From the plot of thermoelectric power against temperature, the nature of films has been identified. These parameters are found to influence the figure of merit of the alloy films