Characterization of thin films by means of soft X-ray reflectivity measurements

The suitability of soft x-ray reflectivity measurements for the characterization of thin films and surface layers is discussed. Especially the detection and quantification of oxidized surface layers is of interest for different applications. The evaluations of angular dependent measurements on a Kanigen mirror and on aluminum coated transmission filters for the German X-ray astronomy satellite ABRIXAS are presented, For Nickel films it is shown that a thin carbon coating prevents oxidation. The measurements were performed at the soft x-ray reflectometer at the Hamburg synchrotron radiation laboratory in the energy region 30 eV - 800 eV. In order to resolve the structure of the sample perpendicular to the surface, consistent least square fits of theoretical reflectivity curves have to be required for different photon energies.