Effects of O2/Ar ratio and annealing on the properties of (Ba,Sr)TiO3 films prepared by RF magnetron sputtering

Perovskite-structure (Ba,Sr)TiO3 (BST) thin films were prepared on Pt/SiO2/Si substrates by RF magnetron sputtering with various O-2/Ar ratios and subsequent annealing. The crystallinity and electrical properties of the films were investigated. It was demonstrated that the electrical properties, such as leakage current and capacitance, of the films depend strongly on the oxygen content of the sputtering gas. With increasing oxygen content of the sputtering gas, the leakage current decreases and the capacitance increases. Both the dielectric constant and the leakage current density increase upon annealing. It is believed that the electrical properties of BST films depend strongly on the grain size and surface roughness of the films.