Optical properties of silicon titanium oxide mixtures prepared by metallic mode reactive sputtering

摘要

In this paper different SiO_2-TiO_2 mixtures are prepared by metallic mode reactive sputtering. The samples were sputtered from cylindrical targets in a sputter-up configuration using an additional plasma source for oxidization. The different ratios of SiO_2 and TiO_2 in the mixtures are prepared by a target sputtering power variation. Optical film properties of the mixtures such as refractive index, which is determined by ellipsometric measurements, and optical bandgap, which is measured by photometric (transmission) measurements, are investigated. The thin-film structure is investigated by x-ray diffraction analysis and the stress of the films is presented. It is shown that the metallic mode reactive sputtering in the present configuration is applicable to continuously tune optical and mechanical properties. Finally the sputtered mixed materials are compared with other optical standard materials such as Nb_2O_5, Ta_2O_5, HfO_2, and Al_2O_3.