Annealing Effect on the Structural and Optical properties of SiOx films deposited by HFCVD: Features for its possible use as Optical Sensor

Non-stoichiometric silicon oxide (SiOx) with embedded Si nanoparticles (Si-nps) shows novel physical characteristic, which permits its use in optoelectronic devices as photodetectors and light emitters. In this work, a detailed analysis of the structural and optical properties of silicon rich oxide films deposited via hot filament chemical vapor deposition is done. SiOx films with different Si content were obtained at different hydrogen flow. FTIR spectra show vibrational bands related to the presence of hydrogen in as-deposited SiOx films. This band is more intense as the hydrogen flow is increased, but disappears after thermal annealing. SiOx films exhibit a broad photoluminiscence (PL) spectra with main peaks at 700 and 750 nm. The PL band at 700 nm is enhanced as the hydrogen content in the SiOx films is increased. XPS spectra show a high Si concentration and a low oxygen concentration in the SiOx films. Transmittance spectra have a shifted to high wavelength after thermal annealing, and optical band gap was from 2.34 to 3.95 eV.