Abstract
An electric-current assisted thermal treatment is demonstrated to be an effective process for eliminating crystal lattice defects and improving thermoelectric properties of both Bi-Sb-Te and Bi-Se-Te nanocrystalline thin films. A model based on electromigration-induced preferential Sb and Te diffusion is proposed to explain the observed Sb-rich and Te precipitation as well as the enhancement of Seebeck coefficient and electrical conductivity of the electrically stressed thin films. Owing to anisotropic diffusion and electrical transport properties, charged lattice defects are preferentially eliminated in the direction parallel to the basal plane of bismuth telluride crystal under electric current stressing. The presented current assisted annealing approach can be an efficient postdeposition treatment that prevents from gross grain growth and evaporation of volatile constituents in Bi-Te based nanocrystalline thin films during high-temperature annealing process. © 2010 American Institute of Physics.