A new EXAFS method for the local structure analysis of low-Z elements

Abstract

A unique analytical method is proposed for local structure analysisviaextended X-ray absorption fine structure (EXAFS) spectroscopy. The measurement of electron energy distribution curves at various excitation photon energies using an electron energy analyzer is applied to determine a specific elemental Auger spectrum. To demonstrate the method, the NK-edge EXAFS spectra for a silicon nitride film were obtainedviasimultaneous measurement of the NKLLAuger and background spectra using dual-energy windows. The background spectrum was then used to remove the photoelectrons and secondary electron mixing in the energy distribution curves. The spectrum obtained following this subtraction procedure represents the `true' NK-edge EXAFS spectrum without the other absorptions that are observed in total electron yield NK-edge EXAFS spectra. The first nearest-neighbor distance (N—Si) derived from the extracted NK-edge EXAFS oscillation was in good agreement with the value derived from SiK-edge analysis. This result confirmed that the present method, referred to as differential electron yield (DEY)-EXAFS, is valid for deriving local surface structure information for low-Zelements.