Thermoelectric Characteristics of n-Type Bi2Te3 and p-Type Sb2Te3 Thin Films Prepared by Co-Evaporation and Annealing for Thermopile Sensor Applications

A thermoelectric thin-film device consisting of n-type Bi2Te3 and p-type Sb2Te3 thin-film legs was prepared on a glass substrate by using co-evaporation and annealing process. The Seebeck coefficient and the power factor of the co-evaporated Bi2Te3 film were −30 µV/K and 0.7 × 10−4 W/K2·m, respectively, and became substantially improved to −160 µV/K and 16 × 10−4 W/K2·m by annealing at 400°C for 20 min. While the Seebeck coefficient of the co-evaporated Sb2Te3 thin film was 72 µV/K, it increased significantly to 165–142 µV/K by annealing at 200–400°C for 20 min. A maximum power factor of 25 × 10−4 W/K2·m was achieved for the co-evaporated Sb2Te3 film by annealing at 400°C for 20 min. A thermopile sensor consisting of 10 pairs of n-type Bi2Te3 and p-type Sb2Te3 thin-film legs exhibited a sensitivity of 2.7 mV/K.