Background Au coatings are widely used as mirrors in synchrotron radiation. Decreasing the surface roughness of Au coatings to reduce scattering signals is still a major difficult problem. [Purpose] This paper aims to study the effect of Pt inter-layer on the surface roughness of Au coatings. [Methods] Based on the research of Au coatings at home and abroad, a new type of Au-Pt coatings was prepared by inserting Pt inter-layer into Au coatings. Effects of various thickness of Pt inter-layer were evaluated by using atomic force microscope (AFM) and X-ray diffractometer (XRD). Finally, IMD software was employed to calculate the reflectivitiesreflectivity of traditional Au coatings and new Au-Pt coatings based on the results of AFM measurement. [Results] AFM measurements show that when Pt inter-layer with 1 nm thickness is inserted into the Au coating at 1 nm interval. The surface roughness of this new Au-Pt coating is less than 0.3 nm, which is obviously less than that of the traditional Au coating. XRD measurement shows that the insertion of Pt layers can effectively inhibit the crystallization of Au coatings, and with the decrease of the thickness of Au film between Pt inter-layers, the crystallinity of the Au coatings decreases significantly. Compared with traditional Au coatings, the reflectivity of new Au-Pt coatings is similar, but the surface roughness of new Au-Pt coatings is smallersmaller, and the scattering signal intensity is reduced, hence the practical performance of mirrors is improved. [Conclusion] This paper provides a reference for the fabrication of Au-Pt mirrors with high transmission efficiency and reflectivity for synchrotron radiation.

N-doped nickel thin films were fabricated by direct current reactive magnetron sputtering, with varying nitrogen contents (0%-20%) added to the sputtering gas (Ar). To investigate the effect of nitrogen contents on morphology, microstructure, chemical composition and intrinsic stress of nickel thin films, characterizations were carried out using grazing incidence X-ray reflectivity (GIXRR), X-ray scattering (XRS), atomic force microscopy (AFM), X-ray diffraction (XRD), cross-sectional transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and intrinsic stress measurements. GIXRR and AFM results showed that the roughness achieves minimum with 8% nitrogen, corresponding to minimum average grain size obtained by XRS and XRD measurements. XRD patterns simultaneously indicated that the position and intensity of the Ni(111) and Ni(200) peaks shifted. This is because Ni lattice structure changed after the introduction of N atoms at interstitial sites, which were octahedrally surrounded by Ni atoms. Cross-sectional TEM images confirmed that Ar + 8%N-2 as sputtering gas can suppress the crystallization and effectively smoothen the surface of Ni film. Moreover, no nickel nitride was found in the N-doped Ni films by XPS analysis and the intrinsic stress remained unchanged after the addition of 8% nitrogen.

Gold films deposited by direct current magnetron sputtering are used for synchrotron radiation optics. In this study, the microstructure and surface roughness of gold films were investigated for the purpose of developing high-reflectivity mirrors. The deposition process was first optimized. Films were fabricated at different sputtering powers (15, 40, 80, and 120 W) and characterized using grazing incidence X-ray reflectometry, X-ray diffraction, and atomic force microscopy. The results showed that all the films were highly textured, having a dominant Au (111) orientation, and the film deposited at 80 W had the lowest surface roughness. Subsequently, post-deposition annealing from 100 to 200 °C in a vacuum was performed on the films deposited at 80 W to investigate the effect of annealing on the microstructure and surface roughness of the films. The grain size, surface roughness, and their relationship were investigated as a function of annealing temperature. AFM and XRD results revealed that at annealing temperatures of 175 °C and below, microstructural change of the films was mainly manifested by the elimination of voids. At annealing temperatures higher than 175 °C, grain coalescence occurred in addition to the void elimination, causing the surface roughness to increase.

Narrowband Mg/SiC multilayer mirrors working around 30.4 nm with a significantly reduced bandwidth (FWHM ≈ 0.7 nm) basing on high order reflection have been designed and fabricated by direct-current (DC) magnetron sputtering.