Study of Reflectivity and Microstructure of Mo/Be Multilayer Mirrors

Abstract

The reflection coefficient and microstructure of Mo/Be multilayer mirrors were studied as functions of Γ, the ratio of the Mo layer thickness to the period dp. The thickness and period of the layers were studied using X‑ray diffraction (wavelength 0.154 nm). Clearly defined high-intensity Bragg reflection peaks indicate good reproducibility of layer thicknesses over the depth of the multilayer structure and high quality of interfaces. The reflectivity of the mirror at a wavelength of 11.4 nm was maximum 62% at Γ = 0.42. It sharply decreased at higher and lower values of Γ. Both Mo and Be layers at Γ = 0.42 were polycrystals, which were studied using X-ray diffraction and Raman spectroscopy, respectively. It was also found that the sizes of crystallites almost coincided with the thicknesses of the Be and Mo layers in the period.