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

Abstract

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 mu V/K and 0.7 x 10(-4) W/K-2.m, respectively, and became substantially improved to -160 mu V/K and 16 x 10(-4) W/K-2.m by annealing at 400 degrees C for 20 min. While the Seebeck coefficient of the co-evaporated Sb2Te3 thin film was 72 mu V/K, it increased significantly to 165-142 mu V/K by annealing at 200-400 degrees C for 20 min. A maximum power factor of 25 x 10(-4) W/K-2.m was achieved for the co-evaporated Sb2Te3 film by annealing at 400 degrees 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.