Improved XPS analysis by visual inspection of the survey spectrum

In this paper, we have revisited a well-known issue in quantitative X-ray photoelectron spectroscopy (XPS) analysis: when quantitative XPS analysis is based solely on measured peak intensities, this can give rather confusing and misleading results. The problem is caused by peak intensity attenuation with photoelectron distance traveled in the sample and is an issue for samples where the atomic concentration varies substantially over the outermost similar to 5nm. This is however the most significant depth range for many of the practical applications of nano-structures which is today of increasing technological importance. We discuss 3 different methods to correct for the attenuation effect and their limitations. It is then pointed out how one can, by visually comparing observed peak shapes to a set of model spectra, often get a rough idea of the atom depth distribution in the surface region of the sample. This provides a practical tool to supplement the information obtained with XPS analysis based on peak intensities and chemical state information obtained from high-resolution spectra.