Orientation optimization for high performance Mg 3 Sb 2 thermoelectric films via thermal evaporation.

Low-cost, highly efficient thermoelectric thin-film materials are becoming increasingly popular as miniaturization progresses. Mg 3 Sb 2 has great potential due to its low cost and high performance. However, the fabrication of Mg 3 Sb 2 thin films with high power factors (PFs) poses a certain challenge. In this work, we propose a general approach to prepare Mg 3 Sb 2 thin films with excellent thermoelectric properties. Using a two-step thermal evaporation and rapid annealing process, (001)-oriented Mg 3 Sb 2 thin films are fabricated on c -plane-oriented Al 2 O 3 substrates. The structure of the film orientation is optimized by controlling the film thickness, which modulates the thermoelectric performance. The PF of the Mg 3 Sb 2 at 500 nm (14 μ W·m -1 ·K -2 ) would increase to 169 μ W·m -1 ·K -2 with Ag doping (Mg 3 Ag 0.02 Sb 2 ) at room temperature. This work provides a new strategy for the development of high-performance thermoelectric thin films at room temperature.