Surface Layer Analysis of Si Sphere by XRF and XPS

To reduce the uncertainty of the Avogadro constant for the new definition of the kilogram, the surface analysis of the Si sphere produced for the accurate determination of the Avogadro constant is indispensable. In this paper, we conducted the surface quantitative analyses to find out the metallic contaminations on a 1-kg natural Si sphere by X-ray fluorescence analysis. The X-ray photoelectron spectroscopy investigations were also carried out to estimate the thickness of the oxide layer and clarify the chemical binding state of the carbonaceous contamination layer on the surface of a dummy Si sphere.