Electron transport in solids for quantitative surface analysis

Abstract

The influence of electron transport on the signal generation process in electron beam techniques is reviewed. A survey of the fundamental physical quantities for the electron-solid interaction is presented and sources for these quantities in the literature as well as semi-empirical formulae are given. The theoretical approaches used to describe multiple scattering in solids are outlined. These include the partial intensity approach and the continuous slowing down approximation to describe multiple energy losses and the transport approximation to tackle multiple deflections. A detailed description of the Monte Carlo technique is presented because this constitutes an effective means to study transport processes. The different theoretical approaches are illustrated in a survey of applications. These include: quantitative description of the surface sensitivity in Auger and photoelectron spectroscopy; line shape analysis of electron spectra; extracting information on the compositional depth profile from the combined energy/angular distribution in an electron spectrum; quasi-elastic electron reflection; inelastic electron backscattering; depth distribution of production of x-rays caused by electron bombardment; and the surface sensitivity in total electron yield electron spectroscopy. These applications demonstrate that the outlined approaches have a broad field of application, not only for electrons with energies ranging from thermal to the relativistic energy range, but also for other microbeam analysis techniques.

Monte Carlo computations of the electron backscattering coefficient for bulk targets and surface thin films

“…The transport approximation for elastic scattering and its limits of applicability are appropriately discussed in Ref. [14].…”

Quasi first-principles Monte Carlo modeling of energy dissipation by low-energy electron beams in multi-walled carbon nanotube materials

“…14 Contrary to the continuous energy-loss models (e.g., from stopping power theory) widely used for studying irradiation effects in bulk solids, MC models of materials with restricted dimensions (e.g., CNTs and nanodevices in general) must account for secondary-electron cascade generation through the use of discrete (or single-scattering) energy-loss models. [15][16][17] Such models will also complement current computational studies of high-energy electron-beam (e.g., from a transmission electron microscope, TEM) irradiation effects in CNTs lying on substrates from backscattered electrons. 18,19 Binary collision theory has been widely used in this context due to its computational convenience, despite its wellknown simplistic description of the materials excitation properties.…”

Reabsorption of Soft X-Ray Emission at High X-Ray Free-Electron Laser Fluences

“…In each inelastic scattering event, a portion of the electron kinetic energy is transferred to a water molecule, ultimately creating a valence excitation in this molecule. A single primary Auger electron can create tens of valence excitations within a few femtoseconds [26][27][28][29][30]. The detected XE photons result from the radiative decay of the core-ionized molecule [ Fig.…”