Vibrational Spectroscopy of Sulfur-Containing Silicon-Rich Silicon-Oxide Films Fabricated via a Coevaporation Technique

We have fabricated sulfur-containing silicon-rich silica thin films by using a coevaporation technique. Transmission spectra in the infrared region indicated the presence of S atoms participating in the silica networks via Si-S bonds while absorption spectra in the ultraviolet/visible region proved that some of the S atoms were present in the form Of S(2) and S(3) molecules. The optical bandgap energy was inversely proportional to the number of sulfur atoms incorporated. The structural evolution of the thin films is discussed in connection with the S concentration.