Optimized thermoelectric performance of porous Bi0.5Sb1.5Te3 thin films through rapid thermal processing

Porous thermoelectric (TE) materials have attracted considerable interest due to their excellent TE performance and mechanical properties. Porous Bi2Te3-based thin films could trigger the energy filtering effect to realize synergetic optimizations of electrical conductivity and Seebeck coefficient. Rapid thermal processing (RTP) is a high-efficient annealing technique to modulate film microstructures. Herein, a series of porous Bi0.5Sb1.5Te3 thin films were prepared by magnetron sputtering through deposition with substrate heating and subsequent RTP at various temperatures and heating rates. The crystallinity, preferential orientation, and surface morphology could be readily modified, which affect the electrical transport properties distinctly. The configuration of annealing temperature of 623 K and heating rate of 30 K/min leads to the best power factor of 687 μW m−1 K−2, mainly due to the substantially improved mobility via microstructure decorating. This result confirms that the RTP is a feasible and economic strategy to optimize the TE performance of porous thin films.