Mainz, R.; Klenk, R.: In situ analysis of elemental depth distributions in thin films by combined evaluation of synchrotron x-ray fluorescence and diffraction. Journal of Applied Physics 109 (2011), p. 123515/1-13
10.1063/1.3592288
Open Access Version
Abstract:
Abstract In this work we present a method for in situ analysis of elemental depth distributions in thin films by a combined evaluation of synchrotron x-ray fluorescence (XRF) and energy-dispersive x-ray diffraction (EDXRD) signals. We recorded diffraction and fluorescence signals simultaneously during reactive annealing of thin films. By means of the observed diffraction signals the time evolution of phases in the thin films during the annealing processes can be determined. We utilized this phase information to parameterize depth distributions of the elements in the films. The time-dependent fluorescence signals were then taken to determine the parameters representing the parameterized depth distributions. For this latter step, we numerically calculated fluorescence intensities for a given set of depth distributions. These calculations handle polychromatic excitation and arbitrary functions of depth distributions and take into account primary and secondary fluorescence. The influence of lateral non-uniformity of the films as well as accuracy limits of the method are investigated. We apply the introduced method to analyze the evolution of elemental depths distributions and to quantify kinetic parameters during a synthesis process of CuInS2 thin films by reactive annealing of Cu-In precursors in sulfur atmosphere.