Effect of oxygen to argon ratio on properties of (Ba,Sr)TiO₃ thin films prepared on LaNiO₃ /Si substrates

Thin films of (Ba,Sr)TiO₃ (BST) on LaNiO₃ /Si substrates were deposited using rf magnetron sputtering at various (O ₂ /Ar+ O₂) mixing ratios (OMRs). The crystallinity of the films improved significantly as the OMR increased. The dielectric constant increased with increasing OMR and reached a maximum value at 50% OMR. The leakage current density decreased with increasing oxygen flow because of the decrease of oxygen vacancies in films and had a minimum value at 50% OMR. The results for the dielectric constant were interpreted in terms of polarization and stress effect. In addition, the BST films deposited at 600 °C and 50% OMR exhibited a higher figure of merit (FOM), and the value of FOM is calculated to be 40.23.