Elastic electron backscattering from flat and rough Si surfaces

In earlier studies, it has been found that the surface roughness influences only weakly the inelastic mean free path values resulting from elastic peak electron spectroscopy. To address this issue, in the present work, the elastic electron backscattering intensity has been systematically studied in numerous experimental configurations. Measurements were made for the flat Si sample, and for the Si sample with well-defined roughness in the form of long trapezoidal channels. Such structure is a good representation for one-dimensional models used in theoretical description of the surface roughness effects in XPS. It has been found that there is a pronounced influence of the surface roughness on the electron backscattered intensity at the primary beam incidence different from normal. These results were observed at energies of interest for surface sensitive electron spectroscopies, i.e. 200, 500 and 1000 eV. Additionally, the elastic backscattering probability for a flat surface was found to agree well with the theoretical predictions. Correction for the surface energy losses further improved the agreement between theory and experiment.