Chemical solution deposition of biaxially oriented (Ba,Sr)TiO 3 thin films on 〈100〉 Ni

Biaxially oriented Ba 1 - x Sr x TiO 3 (BST) thin films were fabricated under a highly reducing atmosphere (oxygen partial pressure ∼10 - 1 8 atm) on base metal substrates ((100) Ni) using a fluorinated chemical solution deposition method. The degree of film orientation was investigated with respect to film annealing temperature and composition (x = 0, 0.33, 0.5, 0.67, 1). The solution synthesis route included fluorinated solvents, donor-dopants, and chelating agents for control of orientation, defect chemistry, and morphology. Free-energy and phase diagrams guided solution development using halide addition to avoid intermediate BaCO 3 formation and instead produce direct crystallization of BaTiO 3 -type materials from BaF 2 . The degree of (200) orientation of BST films deposited on (100) Ni substrates displayed a compositional dependence for 0 < x < 1, with a maximum orientation Lotgering factor approaching unity. Low-temperature (500 °C) crystallization of highly oriented films was demonstrated for solution-derived BST on Ni, which may have enabling materials integration implications for capacitors and other applications.