Quantitative analysis of the directional elastic peak electron spectroscopy profiles

In this work, the quantitative analysis of the directional elastic peak electron spectroscopy (DEPES) profiles is presented for the Si(1 1 1)7 × 7, Si(1 1 1)√3 × √3R30°-Ag, and Au/Ni(1 1 1) systems. The theoretical DEPES scans for the above samples were obtained with the use of the single scattering cluster (SSC) approximation and were compared with the experimental data. The scattering process of the primary electron beam was analyzed by means of the scattering amplitude calculated for Si and Ag atoms and phase shift. The theoretical and experimental DEPES profiles for the clean and covered Si substrate exhibit similar [1 1 4], [1 1 1], and [1 1 0] intensity maxima characteristic of the [112¯] azimuth. In the experiment a large increase of the background level of DEPES scans for Si(1 1 1)√3 × √3R30°-Ag with respect to Si(1 1 1)7 × 7 was observed. The corresponding theoretical scans exhibit a smaller increase of background intensities. We separated the experimental and theoretical DEPES profiles into the background and the structural components. The theoretical background intensities were calculated by taking into account the damping of primary electrons in the sample. The calculated background can be very well fitted by a cosine function of the polar angle. Structural intensities were obtained by subtracting the fitted background from the DEPES profiles. This procedure was applied to the Au/Ni(1 1 1) system in order to find the population of Au(1 1 1) domains. An improved sensitivity of the R-factor analysis was found when the background subtraction was applied.