Growth and optical performance of short-period W/Al and polished W/Si/Al/Si multilayers
Short-period multilayer mirrors are used in wavelength-dispersive x-ray fluorescence to reflect and disperse elements in the O-Kα– Al-Kα range. In this work, we investigated sputter-deposited 2.5 nm W/Al with 20 periods. Our results show that W/Al is a poor reflector due to a combination of high int...
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Veröffentlicht in: | Journal of applied physics 2023-10, Vol.134 (15) |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Short-period multilayer mirrors are used in wavelength-dispersive x-ray fluorescence to reflect and disperse elements in the O-Kα– Al-Kα range. In this work, we investigated sputter-deposited 2.5 nm W/Al with 20 periods. Our results show that W/Al is a poor reflector due to a combination of high interfacial roughness and strong W–Al intermixing. To address this, we introduced 0.5 nm Si seed layers at the W-on-Al and Al-on-W interfaces each consecutive period, while reducing the Al thickness from ∼2.0 to ∼1.0 nm. The Si seed layers significantly reduced interfacial roughness and W–Al intermixing, which led to an increase in the reflectance of the first Bragg peak at λ = 0.154 nm. To further reduce interfacial roughness, ion beam polishing of the top Si layer was applied at each period. The resulting structure of W/Si/Al/Si with ion beam polishing showed that the reflection coefficient of the first Bragg peak at λ = 0.154 nm was comparable to that of standard W/Si. These findings demonstrate the effectiveness of seed layers combined with polishing techniques in synthesizing smooth, high-reflectance multilayers containing two materials that are otherwise challenging to synthesize. |
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ISSN: | 0021-8979 1089-7550 |
DOI: | 10.1063/5.0168377 |