Stoichiometric Effect of Sb₂Te₃ Thin Film on Thermoelectric Property

Properly selecting electrode materials for antimony telluride (Sb₂Te₃) thermoelectric (TE) thin film enhances the power factor. This study analyzed the compositional variation and measured the TE properties of pristine antimony telluride (Sb₂Te₃), Ni/Sb₂Te₃/Ni, and Cu/Sb₂Te₃/Cu thin films that were aged to simulate real applications. The rapid diffusion of Cu in the Cu/Sb₂Te₃/Cu film resulted in the massive growth of the CuTe intermetallic compound (IMC), which led to Te deficiency. Te deficiency causes the formation of antisite SbTe_′and reduces the power factor. Antisite TeSb_•increases the power factor because the growth of Sb₂O₃on the pristine Sb₂Te₃and Ni/Sb₂Te₃/Ni films, in which almost no Ni diffusion occurs, results in Sb deficiency. The formation of oxides and IMCs alters the stoichiometry of the films. The formation of the NiTe reaction layer at the interface becomes a self-barrier that inhibits Ni diffusion to the Sb₂Te₃film. Herein, a defect reaction is proposed to explain the effects of such changes on the TE properties and the relationship between the stoichiometry of the films and the concentrations of the antisites.