Substrate effect on the electrical properties of sputtered YSZ thin films for co-planar SOFC applications

The physical and electrical properties of sputtered YSZ thin films on various substrates were investigated. The in-plane electrical properties of the films were measured for evaluating YSZ thin film for co-planar SOFC electrolytes. The conductance measured on YSZ over Si substrates was significantly affected by the buffer layer thickness and exhibited higher values than that of YSZ on sapphire. This indicates that electrical leakage occurred through the substrate when Si substrates were utilized. Nevertheless, pure ionic conduction was observed in YSZ/sapphire regardless of the film thickness. It implies that much care should be taken for the selection of substrate materials in measuring or utilizing in-plane conductivity, especially for high temperature applications.