Single-crystal InGaO3(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 InGaO3(ZnO)m films. The sandwich structure of the ZnO/InGaZnO/ZnO resulted in an increase in the ZnO content in the superlattice InGaO3(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.
Bibliographical noteFunding Information:
This work was financially supported by the Grant Nos. 2011-0000082 and 2011-0001650 through the National Research Foundation of Korea funded by the Ministry of Education, Science and Technology (MEST). This research was also financially supported by the Ministry of Knowledge Economy (MKE) and the Korea Industrial Technology Foundation (KOTEF) through the Human Resource Training Project for Strategic Technology.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Polymers and Plastics
- Metals and Alloys