Low-Temperature Synthesis of Single-Phase Barium Strontium Titanate Thin Film with a nm-Seeding Technique and Its Dielectric Properties

Dielectric barium strontium titanate (Ba_0.5Sr_0.5TiO₃, BST) thin films containing crystalline seeds of BST nanoparticles were prepared on indium titanium oxide (ITO) glass electrodes with a complex alkoxide precursor method. BST precursor solution that dispersed the BST particles was spin-coated on the electrode and annealed at various temperatures. Thickness of the film was about 300 nm, and BST particle concentration in the film was varied from 0 to 17 mol%. An unseeded BST film was crystallized into a perovskite structure by annealing at 600C, while the seeding with the 17 mol%-BST particles promoted crystalline growth of BST perovskite and lowered crystallization temperature of the films to 525C. Measurement of dielectric properties at 1 kHz showed that the 4.9 mol% BST-seeded film annealed at 600C had a relative dielectric constant of 303, which was higher than that of the unseeded BST film.