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.
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