Optical characteristics of silica coatings deposited by ozone assisted spray pyrolysis technique

The synthesis of silica coatings by the Ultrasonic Spray Pyrolysis (USP) technique, using ozone and tetraethyl-orthosilicate (TEOS), is reported for different substrate temperatures in the 350 to 550°C range. Deposition rates as high as 3500 Å • min^-1 at a substrate temperature of 550° C were obtained. Average roughness values of up to ∼ 11 Å were obtained for the different substrate temperatures and deposition times. FTIR spectroscopy measurements show characteristic SiO2 absorption bands associated with the Si-O-Si rocking, bending and stretching vibration modes at 450, 810 and 1070 cm^-1, respectively. The behavior of the refractive index for these films was determined by spectral ellipsometry in the 275 to 827 nm wavelength range. It was found that for 450° C films the refractive index values lay within those reported for thermal and atomic layer deposited oxides.