Microstructure-Controlled Deposition of SrTiO₃ Thin Film on Self-Assembled Monolayers in an Aqueous Solution of (NH₄)₂TiF₆−Sr(NO₃)₂−H₃BO₃

Strontium titanate precursor thin films were directly deposited on different self-assembled monolayers (SAM) in an aqueous solution at 40−60 °C. We have investigated the film growth rate, mechanism, and kinetics. The film microstructure and thickness can be controlled by appropriate SAM surfaces and solution conditions, such as the concentration of starting materials, pH, and deposition temperatures. Uniform, smooth, and adhesive films with thickness in the range of 25−480 nm could be successfully prepared on the OH surfaces of UV-modified SAM. The films were transparent and composed of closely packed particles of 20−50 nm, which formed by coalescence of very small particles. The Sr species preferably reacts with intermediate Ti species to produce SrTiO 3 precursor solid when the Sr and Ti species coexisted in the present solution system, resulting in a stoichiometry in terms of Sr/Ti ratio even if the Ti species was excessive.