Density of thin TiO 2 films

Abstract

Thin oxide films have a broad range of applications in optical devices. Titania (TiO 2) is a frequently used oxide material for optical coatings because of its high refractive index (≈ 2.4) and low absorption. The development of devices and optimization of production parameters require proper knowledge of the film properties, such as refractive index, composition, contaminations and density. In thin-film analysis, RBS is usually employed for the determination of the film stoichiometry and contaminations. We have used a combination of RBS analysis and optical measurements to deduce absolute values for the density of thin films. Results for thin TiO 2 films are presented demonstrating the usefulness of this approach. A strong correlation of density and refractive index is found. The density values are compared with data gained by X-ray reflection spectrometry. The differences of the density values obtained by both techniques are discussed, focusing on the uncertainties of the 4He stopping power values.