Drastic improvement of oxide thermoelectric performance using thermal and plasma treatments of the InGaZnO thin films grown by sputtering

• Published in: Acta materialia 2011-10, Vol.59 (17), p.6743-6750
• Main Authors: Seo, Dong Kyu, Shin, Sangwoo, Cho, Hyung Hee, Kong, Bo Hyun, Whang, Dong Mok, Cho, Hyung Koun
• Format: Article
• Language: English
• Subjects: Applied sciences; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; InGaO 3(ZnO) m; Materials science; Metals. Metallurgy; Methods of deposition of films and coatings; film growth and epitaxy; Oxides; Physics; Plasma treatment; Production techniques; Single crystals; Sputtering; Superlattice; Surface treatment; Thermoelectric; Thermoelectricity; Thin films
• ISSN: 1359-6454; 1873-2453
• DOI: 10.1016/j.actamat.2011.07.032

Single-crystal InGaO 3(ZnO) m thin films with periodic superlattice structures suitable for transparent thermoelectric applications were fabricated using a commercially available c-plane sapphire substrate, an epitaxial ZnO buffer layer, a thermal treatment at 900 °C, and an Ar plasma treatment. The introduction of the epitaxial ZnO buffer layer led to a significant reduction in the lattice mismatch at the interface with the InGaO 3(ZnO) m films. The sandwich structure of the ZnO/InGaZnO/ZnO resulted in an increase in the ZnO content in the superlattice InGaO 3(ZnO) m thin films. With respect to thermoelectric properties, the formation of a perfect, layered structure induced an increase in the Seebeck coefficient and, at the same time, a decrease in the thermal conductivity. After complete crystallization, the Ar plasma treatment resulted in a considerable decrease in the electrical resistivity without microstructural changes and without a large decrease in the thermal conductivity. As a result, the thermoelectric properties using n-type oxide semiconductors were dramatically improved.