Highly Porous Nanocluster TiO2 Films Deposited Using APCVD in an Excess of Water Vapor

Abstract

This paper describes high-porosity titanium dioxide films deposited via atmospheric pressure chemical vapor deposition using tetraisopropyl titanate at deposition temperatures of 250 and in excess water vapor. Films deposited at low exhibit a very low refractive index and high porosity , up to 87% of the bulk rutile phase. High-temperature sintering, performed at either 450 or , can be used to tailor the films properties by crystallizing the nanoclusters into the anatase or rutile phase, while retaining a low and high φ. The nanoporous nature of the films has significantly retarded the transformation from anatase to rutile, and after sintering for at , the anatase fraction is still greater than 79%. Such thin films with a high surface area to volume ratio are suitable for use in dye-sensitized solar cells and gas sensors.