Enhanced Thermoelectric Properties and Superlattice Structure of a Bi2Te3/ZrB2 Film Prepared by Ion-Beam-Assisted Deposition

In this study, it was found that a novel superlattice structure can favorably influence the carrier and phonon transport properties of superlattice films. The n-type Bi2Te3/ZrB2 superlattice film was successfully fabricated by simple ion-beam-assisted deposition on a large scale. The composition and microstructure of the films were studied by X-ray diffraction, energy-dispersive X-ray spectroscopy, and scanning electron microscopy. The results show that the multilayered Bi2Te3/ZrB2 film with a modulation period (Lambda) of 12 nm is alternately composed of monolithic Bi2Te3 and ZrB2 layers. The Bi2Te3/ZrB2 superlattice film possesses a relatively rough interface and distinct layer structure. The thermoelectric properties, i.e., electrical conductivity (sigma), Seebeck coefficient (S), and thermal conductivity (kappa), of the Bi2Te3-based films were measured in the in-plane direction. The properties of the Bi2Te3/ZrB2 superlattice film were greatly enhanced in comparison with those of Bi2Te3 and ZrB2 films. The superlattice Bi2Te3/ZrB2 film with a thermoelectric dimensionless figure-of-merit ZT = 1.54 was obtained at room temperature. An in-plane transport mechanism of the superlattice structure was proposed and investigated. Introduction of such a superlattice structure into films is therefore a very promising approach.