Increasing soft x-ray reflectance of short-period W/Si multilayers using B4C diffusion barriers

Dennis IJpes*, Andrey Yakshin, J.M. Sturm, Marcelo Ackermann

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

4 Citations (Scopus)
104 Downloads (Pure)


Short-period multilayer mirrors are used in wavelength-dispersive x-ray fluorescence to extend the wavelength range available with naturally occurring Bragg-crystals. W/Si multilayer mirrors with a period of 2.5 nm are used to reflect and disperse elements in the O-Kα-Al-Kα range. However, the reflectance is far from theoretical due to nanoscale W-Si intermixing and formation of WSix. In this work, B4C diffusion barriers were applied in sputter deposited 2.5 nm W/Si multilayers to inhibit W-Si interaction. A peak reflectance of 45% at 9.7° grazing was measured at a wavelength of 0.834 nm - the highest reported in the literature so far. Diffuse scattering measurements revealed no change in interfacial roughness when applying B4C barriers compared to W/Si. A hybrid grazing incidence x-ray reflectivity and x-ray standing wave fluorescence analysis revealed an increase in W concentration of the absorber layer after the application of B4C barriers. Chemical analysis suggests a partial replacement of W silicide bonds with W carbide/boride bonds from the B4C barrier. The formed WxBy and WxCy instead of WxSiy is hypothesized to increase reflectance at 0.834 nm due to its higher W atomic density.

Original languageEnglish
Article number025302
JournalJournal of Applied Physics
Issue number2
Early online date9 Jan 2023
Publication statusPublished - 14 Jan 2023


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