Design optimization of Si optical window for 4.2 μm wavelength

Complex multilayer thin films (SiO2/Si/SiO2) for optical applications have been designed, prepared and characterized for a Si optical window at 4.2 µm wavelengths. RF magnetron sputtering technique has been used as a deposition process. Post-deposition annealing of the multilayer thin films in the temperatures of 150 and 200 °C, for 10 h at the rate of 10 °C/min, was also performed in order to study the effect of temperatures on spectral characteristics of thin films. Spectral performances of single-sided and double-sided Si/SiO2 film layers were studied to analyze their suitability for optical applications. In the first stage, optimized individual film layers of SiO2 and Si are deposited. After deposition, the single-sided and the double-sided Si/SiO2 film layers are characterized optically and structurally using spectrophotometery, atomic force microscopy and X-ray diffraction.