Determination of thickness and composition of thin films by x‐ray fluorescence spectrometry using theoretical influence coefficient algorithms

Abstract

X-ray fluorescence radiation intensity from analyte in thin film is a complex function of matrix composition and film thickness. Nevertheless, the complicated problem of matrix correction in XRF analysis of these materials can be simply solved by using the concept of theoretical influence coefficients. In this article, two algorithms based on the previous published equation for intermediate-thickness samples are proposed. In the first algorithm, the coefficients are treated as constants; in the second one, the coefficients are linear functions of sample thickness and concentration of all matrix elements. The coefficients are calculated from composition and relative radiation intensity (calculated from theory) of hypothetical pure element films and binary films. The calculations are presented in detail on Fe-Cr-Ni ternary films as an example. The capability of the algorithms is demonstrated with hypothetical Fe-Cr-Ni ternary systems and binaries Fe-Cr, Fe-Ni and Cr-Ni of thickness from 0.01 to 2 mg cm −2 . Diverse compositions of these specimens are in the range 5-95% (m/m) of each element. The algorithms are also verified using experimental data of Fe-Ni binary system films and Cu films taken from literature. Obtained results indicate the usefulness of the proposed algorithms for simultaneous and accurate determination of the chemical composition and thickness of thin film materials. Moreover, the calibration procedure is very clear and interpretation of the data is easy for the analyst, which is a serious advantage of the proposed algorithms over fundamental parameters methods.

Quantification in X-Ray Fluorescence Spectrometry

“…In the next paper (Sitko, 2008b), two algorithms of constant and linear coefficients for simultaneous determination of composition and thickness of thin films were proposed. This time, the coefficients are not calculated directly from theory but from the relative radiation intensity (calculated from theory) of hypothetical pure element films and binary films.…”

Study of epitaxial selective area growth In1−xGaxAs films by synchrotron μ-XRF mapping

“…34,39 The a i , c i and, a ij coefficients are generally considered as constants when the concentration and thickness ranges are limited, nevertheless the calculation is more precise (and more complicated) when they are treated as linear functions of sample thickness and concentration of all matrix elements. We decided to adopt this procedure, which is described in details by Sitko, 36 and we realized a script in PythonÔ, which can be used for every kind of film containing three elements.…”

“…In this case FP methods can be applied for the simultaneous determination of the thickness and chemical composition but requires the additional use of at least a reference sample. Due to the peculiarity of our sample, that is an intermediate-thickness In 1Àx Ga x As film in which both composition and thickness are changing from point to point, in a mm scale, we applied the approach proposed by Sitko, [34][35][36] that combines the features of both FP and IC models.…”

Quantitative X-ray fluorescence analysis of samples of less than ‘infinite thickness’: Difficulties and possibilities

“…In Ref. [102], the calculation of influence coefficients from composition and relative radiation intensity (calculated from theory) of hypothetical pure element films and binary films was developed. In this way, two algorithms of constant and linear coefficients for simultaneous determination of composition and thickness of thin films were proposed.…”