Unique hierarchical structure and high thermoelectric properties of antimony telluride pillar arrays.

The p-type antimony telluride (SbTe) pillar arrays with unique hierarchical architecture have been self-assembled in large scale by a simple vacuum thermal evaporation technique. The composition and the microstructure of the films are studied by X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy, and high-resolution transmission electron microscopy. The results show that the hierarchical film with multi-scale and multi-dimensional structure is well-oriented pillar arrays perpendicular to the substrate. A large number of nanowires (NWs) are assembled into a submicro/micro-scaled pillar, while antisite defects and dislocations as well as other defects are found in the one-dimensional NWs. The growth mechanism of such nanostructure is proposed and investigated. The thermoelectric (TE) properties, i.e., electrical conductivity (σ), Seebeck coefficient ( S), and thermal conductivity ( κ) of the films are measured. The properties of the hierarchical SbTe film have been greatly enhanced in comparison with those of the ordinary SbTe films. A TE dimensionless figure-of-merit ZT = 0.88 in the novel hierarchical SbTe film is obtained at room temperature. [ABSTRACT FROM AUTHOR]