Enhanced Thermoelectric Performance of Tin(II) Sulfide Thin Films Prepared by Aerosol Assisted Chemical Vapor Deposition.

Abstract

Orthorhombic SnS exhibits excellent thermoelectric performance as a consequence its relatively high Seebeck coefficient and low thermal conductivity. In the present work, polycrystalline orthorhombic SnS thin films were prepared by aerosol-assisted chemical vapor deposition (AACVD) using the single source precursor dibutyl-bis(diethyldithiocarbamato)tin(IV) [Sn(C4H9)2(S2CN(C2H5)2)2]. We examined the effects of the processing parameters on the composition, microstructure, and electrical transport properties of the SnS films. Deposition temperature dominates charge transport; the room temperature electrical conductivity increased from 0.003 to 0.19 S·cm-1 as deposition temperature increased from 375 to 445 °C. Similarly, the maximum power factor (PF) increased with deposition temperature, reaching ∼0.22 μW·cm-1·K-2 at 570 K. The power factors for SnS films deposited by AACVD are higher than values from earlier work on SnS bulks and SnS/SnSe films at temperatures up to 520 K. The electronic structure and electrical transport properties of SnS were investigated using density-functional theory to provide an improved understanding of the materials performance. To the best of our knowledge, the thermal conductivity (κ) of SnS film was measured for the first time allowing the figure of merit (zT) for SnS film to be evaluated. A relatively low thermal conductivity of ∼0.41 W·m-1·K-1 was obtained at 550 K for SnS films deposited at 445 °C; the corresponding zT value was ∼0.026. The SnS films are good candidates for thermoelectric applications and AACVD is a promising technique for the preparation of high-performance thermoelectric films.