Gallium-Doped Zinc Oxide Nanostructures for Tunable\nTransparent Thermoelectric Films

Abstract

Ga-doped\nZnO (GZO) transparent nanostructured thin films were fabricated\nvia the magnetron sputtering process, and the effect of the Ga doping\nlevel in Ga_<i>x</i>Zn_1–<i>x</i>O on their thermoelectric performance was investigated. Nanostructured\ncomposite Ga_0.085Zn_0.915O could achieve a power\nfactor up to 1428 μW/mK² at 850 K, which is one of\nthe highest among the reported thin-film GZO and other metal oxides-based\nthermoelectrics. A corresponding thermoelectric generator module using\nGZO as n-type legs was fabricated to attain a maximum power output\nof 230 nW at Δ<i>T</i> = 138 K with an estimated power\ndensity of 19.1 mW cm^–2. First-principles calculations\nwere performed to study the thermoelectric properties of GZO, showing\nthat the calculated result is perfectly consistent with the experimental\nobservation that the maximum power factor was achieved at around 8.5%\nGa doping. In addtion, 10 nanostructured gallium-doped ZnO thin-film\nlegs were fabricated for transparent thermoelectric modules. This\nwork provides an excellent example to foresee the thermoelectric nanostructured\nthin-film material property through the theoretical simulation of\nmaterials, suggesting that modeling plays a big role in designing\nand formulating high-performance thermoelectric materials.