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Auger electron Spectroscopy
Auger electron Spectroscopy
Auger electron Spectroscopy
Auger electron Spectroscopy
Auger electron Spectroscopy
Auger electron Spectroscopy
Auger electron Spectroscopy
Auger electron Spectroscopy
Auger electron Spectroscopy
Auger electron Spectroscopy
Auger electron Spectroscopy
Auger electron Spectroscopy
Auger electron Spectroscopy
Auger electron Spectroscopy
Auger electron Spectroscopy
Auger electron Spectroscopy
Auger electron Spectroscopy
Auger electron Spectroscopy
Auger electron Spectroscopy
Auger electron Spectroscopy
Auger electron Spectroscopy
Auger electron Spectroscopy
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Auger electron Spectroscopy

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electron spectroscopy of core electrons

electron spectroscopy of core electrons

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  • 1. AUGER ELECTRON SPECTROSCOPY PRINCIPLES AND APPLICATIONS Yash CNS CUG
  • 2. WHAT IS AUGER ELECTRON SPECTROSCOPY ? Auger Electron Spectroscopy (AES), is a widely used technique to investigate the composition of surfaces.  First discovered in 1923 by Lise Meitner and later independently discovered once again in 1925 by Pierre Auger [1]  Lise Meitner Pierre Victor Auger 1. P. Auger, J. Phys. Radium, 6, 205 (1925). 2
  • 3. THE PARTICLE-SURFACE INTERACTIONS Auger Electron Spectroscopy Ions Electrons Photons Ions Electrons Photons Vacuum 3
  • 4. BASIC OF AUGER ELECTRON SPECTROSCOPY Auger spectroscopy can be considered as involving three basic steps : (1) Atomic ionization (by removal of a core electron) (2) Electron emission (the Auger process) (3) Analysis of the emitted Auger electrons This last stage is simply a technical problem of detecting charged particles with high sensitivity, with the additional requirement that the kinetic energies of the emitted electrons must be determined. 4
  • 5. PHOTOELECTRON VS. AUGER ELECTRON EMISSION 5
  • 6. AUGER ELECTRON SPECTROSCOPY 6
  • 7. PHYSICS BASIS An Auger transition is therefore characterized primarily by :1. the location of the initial hole 2. the location of the final two holes In general, since the initial ionisation is non-selective and the initial hole may therefore be in various shells, there will be many possible Auger transitions for a given element - some weak, some strong in intensity. AUGER SPECTROSCOPY is based upon the measurement of the kinetic energies of the emitted electrons. Each element in a sample being studied will give rise to a characteristic spectrum of peaks at various kinetic energies. This is an Auger spectrum of Pd metal - generated using a 2.5 keV electron beam to produce the initial core vacancies and hence to stimulate the Auger emission process. The main peaks for palladium occur between 220 & 340 eV. The peaks are situated on a high background which arises from the vast number of so-called secondary electrons generated by a multitude of inelastic scattering processes. Auger spectra are also often shown in a differentiated form : the reasons for this are partly historical, partly because it is possible to actually measure spectra directly in this form and by doing so get a better sensitivity for detection. The plot below shows the same spectrum in such a 7 differentiated form.
  • 8. SITE DIFFERENTIATION CATSYMP19 PRESCHOOL 17TH JAN 2009 8
  • 9. 9
  • 10. SURFACE ANALYSIS DEPTHS CATSYMP19 PRESCHOOL 17TH JAN 2009 10
  • 11. SCANNING AUGER ELECTRON SPECTROMETER 11
  • 12. CATSYMP19 PRESCHOOL 17TH JAN 2009 12
  • 13. 13
  • 14. ELEMENTAL SHIFTS 14
  • 15. QUANTITATIVE SURFACE ANALYSIS: AES By assuming the concentration to be a relative ratio of atoms, we can neglect the terms that depend only on the instrument: The values of S are determined theoretically or empirically with standards. AES is considered to be a semi-quantitative technique 15
  • 16. Auger Analysis Examples A - Chemical composition, thickness and spatial distribution of the elements on cerium conversion layers deposited on galvanised steel. Effect of the treatment time. 16
  • 17. 17
  • 18. AES DEPTH PROFILING: AN EXAMPLE 18
  • 19. CHEMICAL SHIFT 19
  • 20. SEMICONDUCTOR DOPING SHIFT IN AES CATSYMP19 PRESCHOOL 20
  • 21. DOPING MAP BY AES 21
  • 22. THANK YOU FOR ATTENTION FROM YASH 22

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