Substrate and instrumental effects in quantitative Auger electron spectroscopy: the system lead on gold

Abstract

New and previously published AES data on monolayer and surface compound formation during the first stages of deposition of lead on gold are critically examined. The system serves as a 'test case' for quantitative AES. Comparison of results obtained with different single crystals substrates and with different spectrometers show quantitative differences of up to a factor of two. It is not possible to deduce the composition of the surface compound that forms after the first simple monolayer. From experiments in which the primary incident electron energy was varied, evidence is found for unusual diffraction effects in the surface layers. The 72 eV Auger electrons from gold have a wavelength equal to the gold atomic radius. This coincidence would lead to strong diffraction and could partly explain the large discrepancies between different experiments.