Open AccessNitridated Ru/B4C multilayer mirrors with improved interface structure, zero stress, and enhanced hard X-ray reflectance
Author(s) -
Qiushi Huang,
Yang Liu,
Yang Yang,
Runze Qi,
Yufei Feng,
И. В. Кожевников,
Wenbin Li,
Zhong Zhang,
Hui Jiang,
Ling Zhang,
Aiguo Li,
Jie Wang,
Zhanshan Wang
Publication year - 2018
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.26.021803
Subject(s) - materials science , optics , stress (linguistics) , x ray photoelectron spectroscopy , x ray reflectivity , sputtering , analytical chemistry (journal) , argon , optoelectronics , thin film , nanotechnology , nuclear magnetic resonance , atomic physics , chemistry , philosophy , linguistics , physics , chromatography
Ru/B 4 C multilayer mirrors are used for hard X-ray monochromators with moderate spectral resolution and high integral flux. To overcome the problem of large compressive stress inherent in Ru/B 4 C multilayers, a reactive sputtering technique using a mixture working gas of argon and nitrogen with different partial pressures was tested, and the fabricated multilayers had a period of 3 nm. The intrinsic stress was essentially reduced after nitridation and relaxed to zero value at approximately 15% partial pressure of nitrogen in the working gas. Interface roughness was slightly increased which can be caused by the polycrystalline structure inside the nitridated samples. More importantly, the nitridated multilayers showed an enhanced reflectance (67% at 8.04 keV photon energy) as compared with the one fabricated with pure Ar (54%). The structure analysis with transmission electron microscopy and X-ray photoelectron spectroscopy demonstrated that nitrogen incorporated into a multilayer structure was mostly located in the B 4 C layers forming BN compounds, which suppressed the diffusion of boron, stabilized the interfaces and enhanced the reflectance.