Influence of titanium content and temperature on optical and mechanical properties of sol-gel derived TiO₂/γ-glycidoxypropyltrimethoxysilane and methyltrimethoxysilane hybrid organic-inorganic films

The influence of titanium content and heat treatment temperature on the optical and mechanical properties of TiO₂/γ-glycidoxypropyltrimethoxy silane and methyltrimethoxysilane hybrid films processed by the sol-gel technique are studied for photonic applications. Waveguide film with a thickness more than 1.60 μm is prepared by a single spin-coating process and low temperature heat treatment. Thermal gravimetric analysis, UV-visible spectroscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy are used to investigate the optical and structural properties of the hybrid organic-inorganic films. The results indicate that a dense, low absorption, and high transparency in the visible and near infrared range waveguide films can be obtained at a low temperature. The hardness and Young's modulus of the films are characterized by a nanoindenter and they show a dependence on the heat-treatment temperature. Hardness as high as 6.60 Gpa is obtained in 0.5 M titanium content film and heat-treated at 800°C. It is proposed that the high hardness of the film may be related to the carbon and titanium content in the film.