High Temperature Electrical Properties of Co-Substituted La₄BaCu₅O_13+δ Thin Films Fabricated by Sputtering Method

The high-temperature conductivity of the perovskite oxides of a La₄BaCu₅O₁₃₊ (LBCO) thin film prepared by RF sputtering deposition and thermal annealing has been studied. While the bulk LBCO compound was metallic, the LBCO film deposited on a Si substrate by sputtering and a post annealing process showed semiconductor-like conduction, which is considered to be due to the defects and poor grain connectivity in the LBCO film on the Si substrate. The LBCO film deposited on a SrTiO₃ substrate was of high film quality and showed metallic conduction. When the cation site Cu was substituted by Co, the electrical conductivity of the LBCO film increased further and its temperature dependence became smaller. The transport properties of LBCO films are investigated to understand its carrier generation mechanism.