SiON films deposited on Si(111) substrates—new promising materials for nonlinear optics

Experimental measurements of the phototransparency stimulated by the YAG–Nd laser (λ=1.06 μm) in the SiON films deposited on the Si<111> crystalline surfaces show essential dependence on the ratio between the nitrogen and oxygen (N/O) content. Dependencies of the phototransparency on the chemical content, delaying time, pressure and temperature demonstrate essential sensitivity to the N/O ratio. All of the data show that the photoinduced changes in the SiON–Si<111> are caused by both linear and nonlinear optical response function contributions and can be used for non-destructive diagnostic of the film content and thickness. To understand the physics of the observed phenomena, we perform detailed theoretical ab initio molecular dynamic simulations on the ground of the norm-conserving non-local pseudopotential method that give possibility to explain the observed dependencies and to predict the possible changes of the optical constants in the desired directions.