Processing effects on the composition and dielectric properties of hydrothermally derived Ba_xSr_(1−x)TiO₃ thin films

Polycrystalline Ba_xSr_(1−x)TiO₃ (BST) thin films were processed on Pt-coated glass substrates at temperatures below 100 °C by reacting TiO₂ films in alkaline solutions containing Ba²⁺ and/or Sr²⁺. The TiO₂ was deposited by spin-casting a titanium metalorganic precursor onto Pt-coated glass substrates, followed by pyrolysis in air at 400 °C. Film stoichiometry deviated from the initial solution composition, with a preferred incorporation of Sr²⁺ into the perovskite lattice. The BST thin films had dielectric constants ranging from 100 to 185 and dielectric loss values below 0.25. Capacitance–voltage and current–voltage relationships were examined to determine the effect of phase stoichiometry and processing route on dielectric properties.