Atomic layer deposition of photocatalytic TiO2 thin films from titanium tetramethoxide and water

Titanium dioxide thin films were grown by atomic layer deposition (ALD) at 200-400 degreesC from a new titanium precursor, titanium tetramethoxide, and water. As compared with other titanium alkoxides studied earlier, titanium methoxide shows the highest stability with respect to thermal decomposition, and can thus be used over the widest range of temperatures. The films deposited at 250 degreesC and above were polycrystalline with the anatase structure, whereas those deposited at 200 degreesC were amorphous. Except for the film deposited at 200 degreesC, the films contained only minor amounts of carbon and hydrogen residues. The crystalline films were shown to have photocatalytic activity in decomposing both methylene blue in aqueous solution, and solid stearic acid coated on the film surface.