Improved thermoelectric performance of Bi2Se3 alloyed Bi2Te3 thin films via low pressure chemical vapour deposition

Abstract

Thermoelectric generators are attractive for autonomous sensor systems where regular battery replacement would not only cause an increase in the maintenance costs and discontinuity in the operation, but also destroy the concept of a truly autonomous system. Micro-thermoelectric generators utilise thin films of material for energy harvesting which can greatly reduce the amount of material used, which is especially important for rare elements such as tellurium. Thin films of Bi2Te3 were successfully prepared via a single source precursor CVD method. The thermoelectric performance of these films is improved by alloying a Bi2Se3 precursor to deposit ternary Bi2Te3-xSex. The composition of the ternary system is tuned to optimise the combination of carrier concentration and mobility to give a three-fold enhancement of the thermoelectric power factor at 300 K, and six-fold enhancement at 500 K, with respect to Bi2Te3. This improvement from the substitution of Te with Se is believed to be due to donor effects, as well as point defects caused by this substitution.