Control of Microstructure and Orientation in Solution‐Deposited BaTiO ₃ and SrTiO ₃ Thin Films

Columnar and highly oriented (100) BaTiO 3 and SrTiO 3 thin films were prepared by a chelate‐type chemical solution deposition (CSD) process by manipulation of film deposition conditions and seeded growth techniques. Randomly oriented columnar films were prepared on platinum‐coated Si substrates by a multilayering process in which nucleation of the perovskite phase was restricted to the substrate or underlying layers by control of layer thickness. The columnar films displayed improvements in dielectric constant and dielectric loss compared to the fine‐grain equiaxed films that typically result from CSD methods. Highly oriented BaTiO 3 and SrTiO 3 thin films were fabricated on LaAlO 3 by a seeded growth process that appeared to follow a standard “two‐step” growth mechanism that has been previously reported. The film transformation process involved the bulk nucleation of BaTiO 3 throughout the film, followed by the consumption of this matrix by an epitaxial overgrowth process originating at the seed layer. Both BaTiO 3 and PbTiO 3 seed layers were effective in promoting the growth of highly oriented (100) BaTiO 3 films. Based on the various processing factors that can influence thin film microstructure, the decomposition pathway involving the formation of BaCO 3 and TiO 2 appeared to dictate thin film microstructural evolution.