Improving the soft X‐ray reflectivity of Cr/Ti multilayers by co‐deposition of B4C. (9th October 2020)

• Record Type: Journal Article
• Authors: Zhu, Jingtao; Zhang, Jiayi; Li, Haochuan; Tu, Yuchun; Chen, Jinwen; Wang, Hongchang; Dhesi, Sarnjeet S.; Cui, Mingqi; Zhu, Jie; Jonnard, Philippe
• Is Part Of: Journal of synchrotron radiation. Volume 27:Part 6(2020)
• Page Start: 1614
• Page End: 1617
• Publication Date: 2020-10-09
• Subjects: synchrotron radiation -- multilayer -- interface -- Cr/Ti; Synchrotron radiation -- Periodicals; Free electron lasers -- Periodicals; 539.73505
• DOI: 10.1107/S1600577520011741
• Languages: English
• ISSNs: 0909-0495

Abstract

Abstract : Systematic analysis on interfaces of Cr/Ti multilayers has been performed. The near‐normal‐incidence reflectivity increases from 4.48% to 15.75% at a wavelength of 2.73 nm using co‐deposition of B4 C. Abstract : The `water window', covering 2.4–4.4 nm, is an important wavelength range particularly essential to biology research. Cr/Ti multilayers are one of the promising reflecting elements in this region because the near‐normal‐incidence reflectivity is theoretically as high as 64% at 2.73 nm. However, due to multilayer imperfections, the reported reflectivity is lower than 3% for near‐normal incidence. Here, B and C were intentionally incorporated into ultra‐thin Cr/Ti soft X‐ray multilayers by co‐deposition of B4 C at the interfaces. The effect on the multilayer structure and composition has been investigated using X‐ray reflectometry, X‐ray photoelectron spectroscopy, and cross‐section electron microscopy. It is shown that B and C are mainly bonded to Ti sites, forming a nonstoichiometric TiB x C y composition, which hinders the interface diffusion, supresses the crystallization of the Cr/Ti multilayer and dramatically improves the interface quality of Cr/TiB x C y multilayers. As a result, the near‐normal‐incidence reflectivity of soft X‐rays increases from 4.48% to 15.75% at a wavelength of 2.73 nm.