Effect of zirconium oxide local structure on soft x-ray optical properties near the oxygen K-edge region

Zirconium oxide thin film serves as one of the potential material candidates in extreme ultraviolet/soft x-ray optics applications. The suitability of its application can be justified by investigating its optical performance in the working energy range. In this study, we have investigated the soft x-ray optical properties of a zirconium oxide thin film near the O K-edge region using the energy-dependent soft x-ray reflectivity (SXR) technique. The SXR and absorption measurements are performed using the Indus-2 soft x-ray reflectivity beamline BL-03. The optical constants (delta and beta) in the energy range of 500-560eV covering O K-edge are extracted by applying Kramers-Kronig relations. Experimentally obtained delta and beta profiles show a prominent e(g) and t(2g) feature in the vicinity of O K-edge with the crystal field splitting of 2.9eV. All features observed in the delta and beta spectra are correlated with their electronic structure and composition of the zirconium oxide thin film. Details of correlation between structural and optical properties as determined by x-ray absorption spectroscopy, x-ray photoelectron spectroscopy, and SXR analyses are discussed.