Systematic investigation of the properties of TiO2 films grown by reactive ion beam sputter deposition

Abstract

TiO2 films were grown by ion beam sputter deposition under systematic variation of ion beam parameters (ion species, ion energy) and geometrical parameters (ion incidence angle, polar emission angle) and characterized with respect to film thickness, growth rate, structural properties, surface topography, composition, optical properties, and mass density. The angular distributions of film thickness and growth rate show an over-cosine shape, which is tilted in forward direction. All films are amorphous and the surface roughness is below 0.22nm. The investigation of the composition revealed stoichiometric TiO2 with implanted backscattered primary particles. The optical properties were analysed using the Tauc Lorentz (TL) model. The amplitude parameter of the TL model was found to vary systematically with the scattering angle, whereas the impact on the other TL parameters is negligible. Mass density follows the same trends as the optical properties, i.e. optical properties and mass density are correlated. Surface roughness, atomic fraction of implanted primary particles, optical properties and mass density show similar systematic variations with process parameters, especially, with the scattering geometry (i.e. scattering angle). Ion species, ion energy and ion incidence angle have no or only a small impact. The variations in the film properties are tentatively assigned to changes in the angular and energy distribution of the sputtered target particles and backscattered primary particles.