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

摘要

Bismuth-telluride-based alloy thin film thermoelectric generators are fabricated by a flash evaporation method. We prepare Bi0.4Te3.0Sb1.6 (p-type) and Bi2.0Te2.7Se0.3 (n-type) powders for the fabrication of the flash evaporated thin films. The overall size of the thin film thermoelectric generators, which consist of 7 pairs of legs connected by aluminum electrodes, is 20mm by 15mm. Each leg is 15mm long, 1mm wide and 1μm 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 oC to 250 oC. The highest output voltage of 83.3 mV and estimated output power of 0.21 μW are obtained from a hydrogen annealing temperature of Ta =250 oC and a temperature difference of ΔT = 30K. The hydrogen annealing temperature of Ta = 250 oC 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 K2) and n-type thin film (-179.3 μV/K, 1.5 mΩ cm, 21.5 μW/cm K2).