Fabrication of a p-type Sb2Te3 and n-type Bi 2Te3 thin film thermocouple

A thin film Sb₂Te₃-Bi₂Te₃ based thermocouple was fabricated. P-type antimony telluride thin films and n-type bismuth telluride thin films have been deposited by co-evaporation on to glass substrates. The conditions for deposition have been investigated as a function of substrate temperature (T_s ) and flux ratio (F_r = F(Te)/F(Sb,Bi)) and optimised to achieve a high thermoelectric power factor. The qualities of deposited films, e.g. structure, composition and morphology, have been examined by X-ray diffraction (XRD), energy dispersive X-ray analysis (EDXA), flame atomic absorption spectroscopy (FAAS) and atomic force microscope (AFM). The thermoelectric properties of the thin films have been studied by room temperature measurement of the Seebeck coefficient, Hall coefficient and electrical resistivity. It has been observed that the Seebeck coefficient and electrical conductivity of p-type Sb₂Te₃ thin film (α_p, σ_p) and n-type Bi₂Te₃ thin films (α_n, σ_n) were found to be about 185 μV/K, 0.32 × 10³ Ω^-1 cm^-1 and -228 μV/K, 0.77 × 10³ Ω ^-1 cm^-1, respectively. From optimal deposition parameters, a thin film thermocouple was fabricated and operated in Peltier mode. The observed maximum value for temperature difference between hot and cold end is about 15 K for a current of 50 mA. The results indicate that good quality antimony telluride and bismuth telluride thin films grown by co-evaporation are promising candidates for use in a micro-Peltier module