Thermoelectric response of textured Sb₂Te₃-BiSb and Sb₂Te₃-Bi₂Te₃ thin film junctions

Surface mounted thin film thermoelectric (TE) devices for localized cooling, power generation, and sensing are topics of immense current interest. Here, we establish the superior TE performance of thin film junctions made of topological insulators (TIs) Bi85Sb15 (BiSb) and Sb2Te3 by comparing their performance with those of Bi2Te3 and Sb2Te3. Thin films of these TIs were first evaluated for their carrier concentration, Hall mobility, resistivity, and thermopower. The Seebeck coefficient of BiSb, Sb2Te3, and Bi2Te3 measured against copper at ambient temperature is -100, +160, and -70 (+/- 10) mu V/K, while their power factors are 0.5, 0.5, and 0.45 (+/- 0.05) 10(-3) W m(-1) K-2, respectively. Single TE junctions of BiSb-Sb2Te3 and Bi2Te3-Sb2Te3 yield a response of 272 and 240 (+/- 10) mu V/K, respectively. This comparative study shows that BiSb is a superior n-type counter electrode for Sb2Te3 compared to the n-type Bi2Te3. Moreover, Bi2Te3 is prone to tellurium antisite disorder, which affects its TE properties significantly.