Optical properties of fluorinated silicon oxide films by liquid phase deposition for optical waveguides

Optical properties of fluorinated silicon oxide (SiOF) films for optical wa veguide in optoelectronic devices were investigated, The SiOF films are for med at 25 degrees C by a liquid phase deposition (LPD) technique using a su persaturated hydrofluosilicic acid (H2SiF6) aqueous solution. Two main abso rption peaks corresponding to Si-O and Si-F bonds were observed at the wave numbers of 1090 and 930 cm(-1) in Fourier transform infrared (FTIR) spectru m, respectively. The LPD-SiOF films show very little content of water compo nents such as SI-OH bonds and ON group. Although the transmittance for 600- nm-thick LPD-SiOF film gradually decreased from the wavelength around 700 m m, the relative transmittances to quartz glass are over 98% in the waveleng th region from 350-2500 nn, The concentration of fluorine atoms in the LPD- SiOF film was about 5%, and the calculated composition was SiO1.85F0.15. Th e calculated refractive index from the polarizability for LPD-SiOF film was 1.430, and agrees very well with the measured value at the wavelength of 6 32.8 mn by ellipsometry. The dispersion of refractive index was evaluated a nd fitted to a three-term Sellmeier's dispersion equation. The zero dispers ion wavelengths for the LPD-SiOF and thermally grown SiO2 films were 1.271 and 1.339 mu m, respectively.