Structural and optical characteristics designed by sputtering deposition conditions of the oxide thin films

Abstract

The influence of film thickness on the structural and optical properties of silicon dioxide (SiO2) and zinc oxides (ZnO) thin films deposited by radio frequency magnetron sputtering on quartz substrates was investigated. Deposition conditions were optimized to achieve stoichiometric thin films. The orientation of crystallites, structure and composition were investigated by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), while the surface topography of samples was analyzed using scanning electron microscopy (SEM). The optical characteristics were measured for samples with the same composition but obtained with different deposition parameters, such as increasing thickness. Optical constants (i.e. refractive index n, extinction coefficient k, and absorption coefficient α) of the SiO2 and ZnO oxide films were determined using Swanepoel’s method from the transmission spectra recorded in the range 190 - 2500 nm, while the energy bandgap was calculated from the absorption spectra. The influence of thickness on the structural and optical properties of the oxide films was investigated. A good optical quality and real performance was noticed, which makes these thin films deem worthy of integration into metamaterial structures.