Improvement of thermoelectric properties induced by uniquely ordered lattice field in Bi2Se0.5Te2.5 pillar array

In this study, it was found that uniquely ordered lattice field favors transport of carriers but hinder that of phonons. The n-Bi2Se0.5Te2.5 pillar array film was successfully achieved by a simple ion beam assisted deposition technique. This oriented pillar array structure is clear with pillar diameter of about 30 nm, exhibiting a uniquely ordered lattice field. The properties of the ordered Bi2Se0.5Te2.5 pillar array were greatly enhanced in comparison with those of the ordinary film. The Bi2Se0.5Te2.5 pillar array with a thermoelectric dimensionless figure-of-merit ZT = 1.28 was obtained at room temperature. The in-plane transport mechanisms of the ordered pillar array and the ordinary structures, lattice field model, are proposed and investigated. The specially ordered lattice field is the main reason for the properties enhancement observed in the Bi2Se0.5Te2.5 film. Introduction of such ordered lattice field into TE films is therefore a very promising approach. (C) 2014 Elsevier Inc. All rights reserved.