Preparation of a TiO₂ film coated Si device for photo-decomposition of water by CVD method using Ti(OPrⁱ)₄

Growth of a TiO₂ film on a Si wafer by CVD method was studied for a new design of chemically stable device which is useful in the visible region and increases the efficiency of the photocatalytic decomposition process of water. This design is made up of a monolithic structure of a TiO₂ thin film and a Si solar cell. The TiO₂ film was deposited on a Si substrate by the vapor phase reaction of Ti(OPrⁱ)₄ with water at temperatures from room temperature to 473 K. At room temperature, a rough TiO₂ film with a nano-sized cone shape deposit was observed by AFM. The smooth TiO₂ film of ∼ 10 nm thickness was obtained by the reaction of 80 Pa Ti(OPrⁱ)₄ and 493 Pa water vapors at 473 K for 10.8 ks. The surface and the thickness of the film became rougher and thicker, respectively, with increasing pressure of Ti(OPrⁱ)₄.