Impact of B4C co-sputtering on structure and optical performance of Cr/Sc multilayer X-ray mirrors
Abstract
The influence of B4C incorporation during magnetron sputter deposition of Cr/Sc multilayers intended for soft X-ray reflective optics is investigated. Chemical analysis suggests formation of metal: boride and carbide bonds which stabilize an amorphous layer structure, resulting in smoother interfaces and an increased reflectivity. A near-normal incidence reflectivity of 11.7%, corresponding to a 67% increase, is achieved at λ = 3.11 nm upon adding 23 at.% (B + C). The advantage is significant for the multilayer periods larger than 1.8 nm, where amorphization results in smaller interface widths, for example, giving 36% reflectance and 99.89% degree of polarization near Brewster angle for a multilayer polarizer. The modulated ion-energy-assistance during the growth is considered vital to avoid intermixing during the interface formation even when B + C are added. ; Funding agencies: Swedish Science Council; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009 00971]
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Englisch
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Linköpings universitet, Tunnfilmsfysik; Linköpings universitet, Tekniska fakulteten; SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California, USA; Center for X-Ray Optics, Lawrence Berkeley National Lab, Berkeley, California, USA; Institute for Nanometre Optics and Technology Helmholtz Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, Berlin, Germany
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