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KMID : 1151820180120010101
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Journal of the Korean Society of Radiology
2018 Volume.12 No. 1 p.101 ~ p.106
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Analysis of Reflectivity for Interfacial Roughness of Depth-Graded W/Si Multilayer Mirror
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Chon Kwon-Su
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Abstract
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Multilayer mirrors have widely been used for monochromatization of X-ray with high reflection efficiency. The reflected X-ray energy or wavelength is determined by the d-spacing of a multilayer mirror and the incidence angle. The reflectivity critically depends on the number of bilayers and surface roughness on each interface. The multilayer mirror has a structure of alternative deposition of high and low Z-elements on the substrate. Each interface should be considered in the calculation of reflectivity. In this paper, we examine the degradation of reflectivity by the inter-diffusion combined with surface roughness on each interface for a W/Si multilayer mirror. In the depth-graded W/Si multilayer mirror, the FWHMs for angle and energy were larger than them of the uniform multilayer mirror. Inter-diffusion considerable gave rise to the degradation of reflectivity. To obtain measured reflectivity closed to the expected reflectivity, the inter-diffusion on W-Si and Si-W interfaces should be considered.
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KEYWORD
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X-ray Optics, Multilayer Mirror, Reflectivity, Inter-diffusion
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