Orientation optimization for high performance Mg₃Sb₂ thermoelectric films via thermal evaporation

Low-cost, highly efficient thermoelectric thin-film materials are becoming increasingly popular as miniaturization progresses. Mg₃Sb₂has great potential due to its low cost and high performance. However, the fabrication of Mg₃Sb₂thin films with high power factors (PFs) poses a certain challenge. In this work, we propose a general approach to prepare Mg₃Sb₂thin films with excellent thermoelectric properties. Using a two-step thermal evaporation and rapid annealing process, (001)-oriented Mg₃Sb₂thin films are fabricated on<i>c</i>-plane-oriented Al₂O₃substrates. The structure of the film orientation is optimized by controlling the film thickness, which modulates the thermoelectric performance. The PF of the Mg₃Sb₂at 500 nm (14<i>μ</i>W·m^-1·K^-2) would increase to 169<i>μ</i>W·m^-1·K^-2with Ag doping (Mg₃Ag_0.02Sb₂) at room temperature. This work provides a new strategy for the development of high-performance thermoelectric thin films at room temperature.