Structural and optical properties of titanium oxide thin films deposited by filtered arc deposition

Thin films of titanium oxide have been deposited on conducting (100) silicon wafers by filtered are deposition (FAD). The influence of the depositing Ti+ energy on the structure, optical and mechanical properties of these films has been investigated. The results of X-ray diffraction showed that with increasing substrate bias the film structure changed from an anatase to rutile phase at room temperature with the transition occurring at a depositing particle energy of about 100 eV. The optical properties over the range of 300 to 800 nm were measured using spectroscopic ellipsometry and found to be strongly dependent on the substrate bias. The refractive index values at a wavelength of 550 nm were found to be 2.6 and 2.72 for the anatase and rutile films, respectively. The optical band gap as a function of the substrate bias was also determined and was found to be 3.15 and 3.05 eV for anatase and rutile phases, respectively. Hardness and stress measurements also confirmed the structural transitions. The hardness range of TiO2 films was found to be between 11.6 and 18.5 GPa and the compressive stress was found to vary over the range of 0.7-2.6 GPa. Studies carried out in this paper showed that the properties of the FAD-deposited TiO2 are sensitive to the energy of depositing Ti+. (C) 1999 Elsevier Science S.A. All rights reserved.