EFFECTS OF THERMAL-TREATMENT ON THE STRUCTURE AND PROPERTIES OF SIO2-TIO2 GEL FILMS ON SILICON SUBSTRATES

Solution derived thin films of molar composition 90SiO(2)-10TiO(2) dep osited on c-Si substrates, for use as planar waveguides are characteri zed in terms of thickness and refractive index, by ellipsometry, as a function of isothermal heat treatments. The structural evolution of th e films with thermal treatment is followed by infrared spectroscopy. T he estimated average Si-O-Si intertetrahedral bond angle increases fro m 137 degrees, at room temperature, to 144 degrees, after heating at 9 00 degrees C. The films should be annealed at T > 800 degrees C, in or der to release the residual stresses.