Optical constants of thin silicon films near the silicon L_2,3 absorption edge

Using synchrotron radiation, we determined the optical constants of thin silicon films in the wavelength region near the silicon L(2,3) absorption edge. The extinction coefficient was determined from the transmittance of a thin, unbacked silicon film. The refractive index was determined from the reflectance of a sample consisting of an evaporated silicon film on gold. The thickness of the evaporated silicon film was chosen so that an interference feature appeared in the wavelength region above the edge where the silicon is transmissive. The shape of the interference feature is sensitive to the optical constants of silicon near the edge.