High-performance bismuth telluride thermoelectric thin films fabricated by using the two-step single-source thermal evaporation

Bismuth telluride (Bi2Te3) is an efficient thermoelectric material, and fabricating Bi2Te3 thin films with good thermoelectric properties is a prerequisite to realizing the potential of these materials in microdevice application. Controllable content deposition and low-negative thermal treatment are the two main challenges in preparing high-performance thin films. In this study, stoichiometric Bi2Te3 thin films were successfully fabricated via the two-step thermal vapor process with a single evaporation source. Then, the rapid thermal process, which could avoid component loss, was used to further improve the crystallinity and thermoelectric properties of thin films. The Seebeck coefficient of Bi2Te3 thin films clearly increased after rapid heat treatment, leading to enhanced power factor and good flexibility. Such thin films exhibited low thermal conductivity due to their nano-sized grains, resulting in high ZT of flexible Bi2Te3 thin films.