Method for correcting peak overlaps in quantitative Auger electron spectroscopy of Cr-containing oxides

Abstract

This paper provides a new method for improving the quantitative accuracy of Auger electron spectroscopy (AES) when measuring the surface composition of mixed metal corrosion oxides that contain chromium (Cr). Without this correction, the Cr Auger peak intensity (in the conventional first derivative display mode) is attenuated by its overlap with the oxygen (O) Auger line, leading to significant relative errors (∼30%–70% too low) in the Cr content. A peak fitting method was used to derive basis spectra in the direct mode display (before differentiation) and simulate a wide range of O to Cr ratios. A mathematical function was derived to define a Cr intensity correction factor, as a function of the O/Cr ratio. This method can be conveniently applied to data sets containing many spectra, such as depth profiles. Once corrected, the composition depth profiles obtained by AES are consistent with x-ray photoelectron spectroscopy profiles obtained from similar areas. The approach presented can also be used to generate correction factors for overlapping peaks in the Auger spectra of other material systems.