Optical Properties of Nonstoichiometric Silicon Oxide SiOx (x < 2)

Abstract

The optical properties of amorphous nonstoichiometric silicon oxide (SiO_x) films of variable composition (x = 0.62–1.92) formed by plasma-enhanced chemical vapor deposition are studied in the spectral range of 1.12–4.96 eV. Spectral ellipsometry showed that the refractive index dispersion character allows one to assign the formed SiO_x films to silicon-like films, dielectrics, or intermediate-conductivity-type films depending on the content of oxygen in the gas phase during synthesis. A model of the SiO_x structure for ab initio calculations is proposed and describes well the experimental optical spectra. Ab initio calculations of the dependences of the SiO_x refractive index and band gap on stoichiometry parameter x are performed.