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. Copyright © 2001 John Wiley & Sons, Ltd.

Electron transport in solids for quantitative surface analysis

A new Monte Carlo simulation approach has been developed to describe electron scattering and secondary electron generation processes in solids. This approach is based on the uses of Mott's elastic scattering cross section and Penn's dielectric function. A very good agreement has been found on the energy distribution of backscattered electrons between theoretical calculations and accurate experimental measurement recently made by Goto et al. (1994). This fact confirms that the present Monte Carlo model is very useful for more comprehensive understanding of basic phenomena in electron spec-troscopy and microscopy, particularly in the sub-keV energy region where cascade secondary electrons play a dominant role. In this paper the details of the Monte Carlo procedure are described and further application to the mechanism of secondary electron generation is presented.

A Monte Carlo modeling of electron interaction with solids including cascade secondary electron production

Monte Carlo simulation of electron emission from solids

Elastic backscattering of electrons: determination of physical parameters of electron transport processes by elastic peak electron spectroscopy

We present a fitting calculation of energy-loss function for 26 bulk materials, including 18 pure elements (Ag, Al, Au, C, Co, Cs, Cu, Er, Fe, Ge, Mg, Mo, Nb, Ni, Pd, Pt, Si, Te) and 8 compounds (AgCl, Al2O3, AlAs, CdS, SiO2, ZnS, ZnSe, ZnTe) for application to surface electron spectroscopy analysis. The experimental energy-loss function, which is derived from measured optical data, is fitted into a finite sum of formula based on the Drude-Lindhard dielectric model. By checking the oscillator strength-sum and perfect-screening-sum rules, we have validated the high accuracy of the fitting results. Furthermore, based on the fitted parameters, the simulated reflection electron energy-loss spectroscopy (REELS) spectrum shows a good agreement with experiment. The calculated fitting parameters of energy loss function are stored in an open and online database at http://micro.ustc.edu.cn/ELF/ELF.html.

Calculations of Energy-Loss Function for 26 Materials

We have developed a novel cylindrical mirror Auger electron analyzer with the well defined electric field of 0.1°% and the residual magnetic field of less than 1 mG. The CMA has a coaxial electron gun and the entrance angles are 42.3 o ±6 o . The theoretically calculated energy resolution of 0.24% was obtained and the transmission was estimated to be 5.6%. This CMA can be used to obtain an absolute Auger electron yield with errors in peak heights of 5%, with an uncertainty in the energy position of 0.1 eV (or 0.01%), and with ghost intensities due to scattering of 0.1-0.2%; for energies greater than 10 eV. Samples of polycrystalline gold, silver, and copper have been examined

Y. Sakai

Papers

True Auger spectral shapes: A step to standard spectra