AVS 46th International Symposium
    Applied Surface Science Division Wednesday Sessions
       Session AS-WeM

Paper AS-WeM5
Consistent, Combined Quantitative AES and XPS Digital Data Bases - Convergence of Theory and Experiment

Wednesday, October 27, 1999, 9:40 am, Room 6A

Session: Gaede-Langmuir Award Address and Quantitative Surface Analysis
Presenter: M.P. Seah, National Physical Laboratory, United Kingdom
Authors: M.P. Seah, National Physical Laboratory, United Kingdom
I.S. Gilmore, National Physical Laboratory, United Kingdom
S.J. Spencer, National Physical Laboratory, United Kingdom
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AES and XPS have more aspects in common than they have in distinction. Therefore, tests of aspects for one spectroscopy, applicable to the other, should be validated for both. Digital databases for elemental spectra for both AES and XPS have thus been measured using an electron spectrometer that has fully calibrated intensity and energy axes. This provides true spectra to give absolute Auger electron yields and relative photoelectron yields. The AES database is measured for both 5 and 10 keV electron beam energies, whereas the XPS database is measured for both Al and Mg unmonochromated X-rays at the magic angle. The combination of these databases allows a refinement of the theories to obtain an overall convergence between theory and experiment. Improvements have been obtained by identifying three classes of parameter to consider: (i) parameters for both AES and XPS, such as electron transport, the methodology of evaluation of peak areas and the spectrometer response function, (ii) parameters for AES only, such as the electron ionisation cross section, backscattering and specific electron backgrounds and (iii) parameters for XPS only, such as the photon-ionisation cross section. Using this approach, improvements to the theories of all three classes of parameter and their method of use have been established. The formalism for quantitative analysis in AES and XPS, using relative sensitivity factors, has been revised to develop an accurate matrix-less formalism that is very simple for use by the analyst. This formalism has the same accuracy as the full matrix formalism but its simplicity permits ready extension to systems beyond binary. Details of these and recent advances, particularly with improvements in the background subtraction for the peak area measurement, lead to excellent convergence between theory and the data. This will be discussed, together with outstanding issues for general quantitative analysis with AES and XPS.