Enhancement of thermoelectric properties induced by oriented nanolayer in Bi2Te2.7Se0.3 columnar films

In this paper, it was found that layered and columnar structure can favorably influence the carrier and phonon transport properties of films. The n-Bi2Te2.7Se0.3 columnar film with layered structure was successfully achieved by simple magnetron co-sputtering method at 400 degrees C deposition temperature, due to the more sufficient growth along the in-plane direction induced by the enhanced mobility of deposited atoms. The layered nanostructure is clear with each layer <25 nm in the columnar film. The properties of the Bi2Te2.7Se0.3 columnar film with layered structure were greatly enhanced in comparison with those of the columnar and the ordinary films synthesized respectively at 350 degrees C and 250 degrees C deposition temperature. The layered Bi2Te2.7Se0.3 columnar film with a thermoelectric dimensionless figure-of-merit ZT = 1.27 was obtained at room temperature. The layered column structure was the main reason for the properties enhancement observed in the Bi2Te2.7Se0.3 film. Introduction of such uniquely layered and columnar structure into thermoelectric films is therefore a very promising approach. (C) 2014 Elsevier B.V. All rights reserved.