The effect of (00l) crystal plane orientation on the thermoelectric properties of Bi₂Te₃ thin film

Highly (00l)-oriented pure Bi₂Te₃ films with in-plane layered grown columnar nanostructure have been fabricated by a simple magnetron co-sputtering method. Compared with ordinary Bi₂Te₃ film and bulk materials, the electrical conductivity and Seebeck coefficient of such films have been greatly increased simultaneously due to raised carrier mobility and electron scattering parameter, while the thermal conductivity has been decreased due to phonon scattering by grain boundaries between columnar grains and interfaces between each layers. The power factor has reached as large as 33.7 μW cm^-1 K^-2, and the out-of-plane thermal conductivity is reduced to 0.86 W m^-1 K^-1. Our results confirm that tailoring nanoscale structures inside thermoelectric films effectively enhances their performances.