Fabrication and characterization of bismuth–telluride-based alloy thin film thermoelectric generators by flash evaporation method

Abstract

Bismuth–telluride-based alloy thin film thermoelectric generators are fabricated by a flash evaporation method. We prepare Bi 0.4Te 3.0Sb 1.6 (p-type) and Bi 2.0Te 2.7Se 0.3 (n-type) powders for the fabrication of the flash evaporated thin films. The overall size of the thin film thermoelectric generators, which consist of seven pairs of legs connected by aluminum electrodes, is 20 mm by 15 mm. Each leg is 15 mm long, 1 mm wide and 1 μm thick. We measure the output voltage and estimate the maximum output power near room temperature as a function of the temperature difference between hot and cold junctions of the thin film thermoelectric generators. In order to improve the performance of the generators, a hydrogen annealing process is carried out at several temperatures from 25 °C to 250 °C. The highest output voltage of 83.3 mV and estimated output power of 0.21 μW are obtained from a hydrogen annealing temperature of T a = 250 °C and a temperature difference of Δ T = 30 K. The hydrogen annealing temperature of T a = 250 °C also results in the best electrical performance for both p-type thin film (Seebeck coefficient = 254.4 μV/K, resistivity = 4.1 mΩ cm, power factor = 15.9 μW/cm K 2) and n-type thin film (−179.3 μV/K, 1.5 mΩ cm, 21.5 μW/cm K 2).