Thermal Stability of p-type Bi_2Te_3/Sb_2Te_3 and n-type Bi_2Te_3/Bi_2Te_(2-x)Se_x Thermoelectric Superlattice Thin Film Devices

摘要

Thermolectric devices have been constructed using Bi_2Te_3/Sb_2Te_3 and Bi_2Te_3/Bi_2Te_(2-x)Se_x superlattice thin films. Since these devices are intended for use in systems that will operate at elevated temperatures over their lifetime as in many power conversion applications, thermal stability of the thermoelectric figure of merit is an important consideration. The ZT_e of p-type and n-type superlattice thin film elements was evaluated at specific intervals during exposure to elevated temperatures of 150℃ for up to 60 hrs. Results indicate that the figure of merit for p- and n-type superlattice films is not compromised over time when exposed to these operating temperatures. In fact, both p- and n-type superlattice thin film ZT_e remains very constant or improves slightly when subjected to continuous exposure to elevated temperatures. Evaluation of these thin film thermoelements is reported and implications of these results are considered for thin film thermoelectric modules.