Surface electron inelastic excitations effect substantially the measured peak intensities or peak areas in surface-sensitive electron spectroscopies, and distort the quantitative information. To obtain reliable quantitative information from the electron spectra, the measured intensities (peak areas) should be corrected for these effects.
In the present work, we investigated quantitatively the influence of surface excitations on electron inelastic mean free paths (IMFPs) determined by elastic peak electron spectroscopy (EPES). We used IMFPs obtained from the early EPES measurements of the electron elastic backscattering probability from GaN [1], SiC [2], Cd0.88Mn0.12Te [3] and the Ni standard in the energy range 200–2000 eV. The total surface excitation parameter (SEP) was evaluated using the models of Chen, Kwei et al., and also a semi-empirical approach of Werner et al., and was applied for correcting the EPES IMFPs. These corrected values were then compared with those predicted by the TPP-2M formula.
We found that implementation of the surface-excitation correction improved agreement between the resulting IMFPs for selected wide band gap semiconductors and the TPP-2M values. The extent to which the IMFPs measured by EPES differ from the corresponding bulk values (on account of surface excitations) was found to depend on the semiconductor material with finite surface. Our results also clearly demonstrated the importance of accounting for surface excitations for accuracy of the measured IMFPs.
[1] M. Krawczyk, L. Zommer, A. Jablonski, I. Grzegory, M. Bockowski, Surf. Sci. 566-568 (2004) 1234.
[2] M. Krawczyk, L. Zommer, A. Kosiñski, J. W. Sobczak, A. Jablonski, Surf. Interface Anal. 38 (2006) 644.
[3] M. Krawczyk, A. Kosiñski, A. Jablonski, A. Mycielski, Surf. Sci. 600 (2006) 3744.
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