Stoichiometric Effect of Sb<sub>2</sub>Te<sub>3</sub> Thin Film on Thermoelectric Property
Zhenwei Sun, Kai-Wen Cheng, Siwei Lin, V.K. Ranganayakulu, Yang‐Yuan Chen, Shang‐Jui Chiu, Tai-Wei Lee, Albert T. Wu
Abstract
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 Sb2O3 on the pristine Sb2Te3 and 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 Sb2Te3 film. 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.