Abstract
TiO2 is a very important thin film material in optics, because the refractive index is high, and also it can satisfy the requirements of a hard, dense and chemically stable coating. In our study, the effect of the floating potential, and the resulting ion beam bombardment on the properties of TiO2 thin film deposited by reactive planar magnetron sputtering has been observed. The dense plasma of an unbalanced planar magnetron was 'leaked' onto the substrate, and controlled by permanent magnets placed behind the substrate. This allowed the floating potential to be varied from -3 up to -59V. During sputtering, this bombardment was used as a neutralised ion beam to enhance film growth. To stabilise the oxygen partial pressure, an optical emission controller was used. It gave a complete range of Ti to oxygen ratios. As a result, we obtained samples with a maximum refractive index at 633nm of 2.52 and a deposition rate of about 4X/s. The properties measured were the refractive index, the surface composition and morphology, and the crystallinity. The relationship between the refractive index and the proportions of 'anatase' and 'rutile' crystal structures of the TiO2 film was especially considered. The highest floating potential showed up to 75% 'rutile' contents.
