Optical and structural properties of ZnS0.5Se0.5 films and interference filters based on them

Abstract

In this study, the structural and optical properties of thin films of a ${{\rm ZnS}_{0.5}}{{\rm Se}_{0.5}}$ZnS0.5Se0.5 solid solution, which are used to create multilayer interference coatings for operation in the near- and mid-infrared regions, are investigated. The structural features and phase composition of the initial film-forming material and films obtained by thermal evaporation in a vacuum on substrates of borosilicate glass and single crystals of germanium and silicon are studied by X-ray diffraction analysis. The dispersion dependences of the optical constants are calculated from spectrophotometric measurements of the films studied here in the spectral range of 2–25 µm. The results of designing and manufacturing infrared interference filters using the films studied here are presented, which include a bandpass filter with transmission in the wavelength range of 8–12 µm and a narrow-bandpass filter with maximum transmission at a wavelength of 10.56 µm and a full width at half-maximum of 140 nm.