K. Iqbal *, A. Maqsood, M. Mujahid and M. H. Asghar

School of Chemical and Materials Engineering, National University of Sciences and Technology, Pakistan

Abstract

Thin film multilayer anti-reflection coatings (SiO₂/Si/SiO₂) having thicknesses 286/571/143nm were deposited by RF magnetron sputtering deposition technique on 0.5mm thick Si(100)-substrates. Post-deposition annealing is also carried out in the temperature range 150-650⁰C for 4hr at the rate of 10⁰C /min. Si Optical window was designed at 4.2µm wavelengths and correlated with modeling software. The films are transparent in the 3‐5μm band of the electromagnetic spectrum, firmly adhered to the substrate. The prepared multilayer thin films are characterized optically and structurally using a spectrophotometer, an atomic force microscope, x-ray diffraction and a scanning electron microscope. Optical and structural characterizations show that the %transmittance is between 60% and 75%, no appreciable change in crystal structure and roughness of coatings vary between 9 and 25 nm when annealed in the temperature range of 150‐650⁰C. Local elemental characterization on the surface of the thin film was carried out using energy dispersive spectroscopy. The quantitative result of energy dispersive spectroscopy has also shown that the ratio of Si to O on the film is 0.67:1.