Examination of the use of principal component analysis and target factor analysis for the determination of Auger depth profiles in two magnetic multilayer metal Systems - Cu/Co and Co/Pt

Target factor analysis and principal component analysis have been applied to Auger spectra acquired from two metallic multilayer systems (Cu/Co and Co/Pt) depth profiled using ion beam bevelling, Both multilayers contained alternating 10 nm films, the Co/Pt being capped with 25 nm of Co. The results reveal the expected improvement in the precision of the depth profiles because of the amount of information included in the factor analysis, However, the data sets always contain more factors than expected from the number of different elements present, These extra factors are revealed by examination of the principal components as being due to the depth dependence of the inelastic scattering at energies lower than the Auger features. This yields more information about the samples than can be obtained from inspection of the raw spectra but compromises the accuracy of quantification of the depth profiles.