Corrected electron inelastic mean free paths (IMFPs) for selected wide band semiconductors

Abstract

Elastic peak electron spectroscopy (EPES) has been widely used to determine the electron inelastic mean free paths (IMFPs) in solids. In this work, we investigated quantitatively the influence of surface excitations on electron IMFPs determined by EPES. We used IMFPs obtained from the early EPES measurements of the electron elastic backscattering probability from GaN and Cd0.88Mn0.12Te wideband-gap semiconductors, and the Ni standard in the energy range 200-2000 eV. The total surface-excitation parameter (SEP) was evaluated using Chen and Werner approaches, 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 semiconductors and the TPP-2M values at low-energy (E < 500 eV) electrons. 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 IMFPs measured for GaN. © 2008 IOP Publishing Ltd.