Characteristic depth of the excitation function for Auger electrons in the noble metals Cu, Ag and Au determined by inelastic background analysis

Abstract

We show that the Tougaard method for inelastic background analysis of X-ray photoelectron spectra can be used to obtain information about the depth excitation distribution for electron-excited Auger electrons. Reflection electron energy loss spectroscopy (REELS), X-ray photoelectron spectroscopy (XPS)/X-ray excited Auger electron spectroscopy (XAES), and AES spectra were taken from Cu, Ag and Au samples. The electron-excited spectra were corrected for the background due to the secondary electron cascade and to backscattered primaries. Using the inelastic scattering function obtained from the REELS spectra and assuming the in-depth concentration profile of emitters to be rectangular, we were able to extract the inelastic background as well as the intrinsic Auger spectra. We determined the characteristic depth of excitation dc for several incident beam energies in the range from 600 eV to 4 keV and we found that for all three metals dc increases with increasing energy.