Spectroscopic investigations on sol-gel derived organic-inorganic hybrid films for photonics from ormosils and tetrapropylorthotitanate

Titania/ormosils organic-inorganic hybrid films with a thickness of approximately 1.55-mum were prepared as planar waveguides by a single spin-coating process and low temperature heat treatment. Acid-catalyzed solutions, firstly, gamma-glycidoxypropyltrime-thoxysilane (GLYMO) mixed with tetrapropylorthotitanate, secondly, methyltrimethoxysilane (MTES) mixed with tetrapropylorthotitanate, and thirdly, gamma-glycidoxypropyltrimethoxysilane and methyl trimethoxysilane mixed with tetrapropylorthotitanate were used as precursors. Purely inorganic, crack-free and highly transparent silica-titania films with a thickness of more than 0.5-mum were also obtained after a heat treatment temperature of 500 degreesC. Films were characterized by thermal gravimetric analysis, and certain optical tools such as UV-visible spectra, Fourier transform infrared spectra and Raman spectra. The obtained results indicate that the GLYMO derived films show more shrinkage and the GLYMO and MTES derived films higher refractive index during heating. The hardness and Young's modulus of the films were characterized by a nanoindenter. Hardness as high as 6.83 GPa was obtained in GLYMO and MTES derived film after being heat-treated at 800 degreesC. It has been proposed that the high hardness of the film could be related to the carbon and high titanium content in the film. (C) 2003 Elsevier Science B.V All rights reserved.