Effects of thickness and rf plasma oxidizing on structural and optical properties of SiOxNy thin films

SiO_xN_y thin films were prepared by electron beam evaporation on microscopic glasses and titanium substrates held at room temperature. The effects of thickness and rf plasma oxidizing power/time on structural and optical properties of SiO_xN_y thin films were examined. The experimental results indicated that the thickness affects the structural and optical properties of SiO_xN_y significantly. All the examined films with different thicknesses designated the presence of the hexagonal Si₃N₄ phase. As thickness changed the preferred orientation of hexagonal Si₃N₄ phase is changed. A decrease in transmittance and the optical band gap along with an increase in refractive index are observed with increasing the film thickness. The rf plasma oxidizing power/time also affects the structural and optical properties of SiO_xN_y significantly. The rf plasma treatment processes caused amorphization to the SiO_xN_y films. Slight increase in optical band gap values was observed with increasing rf power/time. Substantial increase in the refractive index, which could be attractive for optoelectronics applications, was obtained at moderate rf plasma processing powers/times.