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C.J. Powell, W.S.M. Werner, W. Smekal:
"Effects of elastic scattering and analyzer-acceptance angle on the analysis of angle-resolved X-ray photoelectron spectroscopy data";
Surface and Interface Analysis, 43 (2011), 1046 - 1056.

We have made calculations of N 1s, O 1s, Si(oxide) 2p, Hf 4f, and Si(substrate) 2p photoelectron intensities at selected emission
angles for films of SiO1.6N0.4 and HfO1.9N0.1 of various thicknesses on silicon. These calculations were made with the National
Institute of Standards and Technology (NIST) Database for Simulation of Electron Spectra for Surface Analysis (SESSA) to
investigate effects of elastic scattering and analyzer-acceptance angle that could be relevant in the analysis of angle-resolved
X-ray photoelectron spectroscopy (ARXPS) experiments. The simulations were made for an XPS configuration with a fixed
angle between the X-ray source (i.e. for the sample-tilting mode of ARXPS) and with Al and Cu Kα X-ray sources. The no-loss
intensities changed appreciably as elastic scattering was switched `on´ and `off´, but changing the analyzer-acceptance angle
had a smaller effect. Ratios of intensities for each line from the overlayer film for the least realistic model condition (elastic
scattering switched `off´, small analyzer-acceptance angle) to those from the most realistic model condition (elastic scattering
switched `on´, finite analyzer-acceptance angle) changed relatively slowlywith emission angle, but the corresponding intensity
ratio for the Si(substrate) 2p line changed appreciably with emission angle. The latter changes, in particular, indicate that
neglect of elastic-scattering effects can lead to erroneous results in the analysis ofmeasured ARXPS data. The elastic-scattering
effectswere larger in HfO1.9N0.1 than in SiO1.6N0.4 (due to the larger average atomic number in the former compound) andwere
larger with the Al Kα X-ray source than with the Cu Kα source because of the larger cross sections for elastic scattering at the
lower photoelectron energies.

XPS; angle-resolved XPS; elastic scattering; analyzer-acceptance angle; silicon oxynitride; hafnium oxynitride