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A Monte Carlo simulation including surface excitation, Auger electron- and secondary electron production has been performed to calculate the energy spectrum of electrons emitted from silicon in Auger electron spectroscopy (AES), covering the full energy range from the elastic peak down to the true-secondary-electron peak. The work aims to provide a more comprehensive understanding of the experimental AES spectrum by integrating the up-to-date knowledge of electron scattering and electronic excitation near the solid surface region. The Monte Carlo simulation model of beam–sample interaction includes the atomic ionization and relaxation for Auger electron production with Casnati's ionization cross section, surface plasmon excitation and bulk plasmon excitation as well as other bulk electronic excitation for inelastic scattering of electrons (including primary electrons, Auger electrons and secondary electrons) through a dielectric functional approach, cascade secondary electron production in electron inelastic scattering events, and electron elastic scattering with use of Mott's cross section. The simulated energy spectrum for Si sample describes very well the experimental AES EN(E) spectrum measured with a cylindrical mirror analyzer for primary energies ranging from 500 eV to 3000 eV. Surface excitation is found to affect strongly the loss peak shape and the intensities of the elastic peak and Auger peak, and weakly the low energy backscattering background, but it has less effect to high energy backscattering background and the Auger electron peak shape. Copyright © 2014 John Wiley & Sons, Ltd.

Metastable neutral helium atoms are highly chemical sensitive to surface dangling bonds. As the basis of a new lithographic technique, a method for fabrication of self-assembled monolayers (SAMs) and mixed SAMs by the irradiation-promoted exchange reaction has been recently developed. Metastable helium atoms irradiation is shown to modify organosilane SAM films and Si–H and Si–OH covering surfaces, which render the surface amendable to further SAM modification. The exposure regions can undergo a second chemisorption reaction to produce an assembly of octadecyltrichlorosilane SAMs. Metastable helium atom beam patterned films can be used as templates for selective buildup of fluorophores, amino group, and biological cells to obtain further surface functionalization. Copyright © 2014 John Wiley & Sons, Ltd.

ZnWO4:Eu nanorods were characterized by SEM, TEM, XRD and Raman spectroscopy. The optical properties were investigated by UV–vis and photoluminescence spectroscopy. The temperature-dependent structure and optical properties of ZnWO4:Eu nanorods have been investigated. It was found that temperature-induced monoclinic phase to molten state transition occurred at 1573 K. The ZnWO4 intrinsic luminescence and Eu3+ emission intensities decreased rapidly with the increase of temperature. Copyright © 2014 John Wiley & Sons, Ltd.

It has been experimentally achieved atomic resolution imaging by using secondary electron (SE) signals in a scanning transmission electron microscope with aberration correction. The underlying physical mechanism needs to be understood and has attracted considerable theoretical interest. Several recent calculations taking account of the inner-shell ionization for high-energy SE production have not included the cascade production of low-energy SE signals which was believed to destroy the local information in SE imaging. In this work, we have developed a new theoretical method, a quantum Monte Carlo simulation, to calculate atomic resolution SE image by including every physical factor in SE generation, transportation and emission for a crystalline solid. This quantum Monte Carlo simulation method combines the Bohmian quantum trajectory method for treating electron elastic scattering and diffraction in a crystal with a conventional Monte Carlo sampling of inelastic scattering events along quantum trajectory paths. Simulation of atomic resolution SE image for atom columns in a copper crystal is performed. The contribution of the inner-shell excitation to atomic resolution SE imaging is studied. Copyright © 2014 John Wiley & Sons, Ltd.

Electron inelastic mean free path can be obtained from a measured elastic peak electron spectroscopy spectrum combined with a Monte Carlo simulation. It is thus necessary to know the influence of various experimental factors to the measured and calculated results. This work investigates the effect of the surface roughness or the surface topography on the intensity of the elastic peak. A Monte Carlo simulation, by taking into account of realistic surface roughness for both Gaussian and nonGaussian type rough surfaces experimentally prepared, has been employed to study the surface topography effect. The simulations of elastic peak electron spectroscopy were performed for both planar and rough Al and Cu surfaces and for varied primary energies ranging from 200 to 2000 eV. To quantify the surface roughness effect, the surface roughness parameter is introduced according to the ratio of elastic peak intensities between a rough surface and an ideal planar surface. Simulation results have shown that surface roughness parameter is important in a certain range of emission angle and particularly for large emission angles. For grazing emission, the elastic peak intensity can be largely enhanced by roughness even at nanometer scale. Copyright © 2014 John Wiley & Sons, Ltd.

Quantitative surface analysis requires knowledge of surface excitations by electrons. These excitations are characterized by the surface excitation parameter (SEP) which represents the surface excitation probability while an electron moves across a solid surface. In this work, a systematic calculation of a SEP database has been performed for 22 materials, including metals, oxides and semiconductors, for electron energies between 100eV and 5000eV, and for angles a of incidence/emission between 0.5 and 89.5 with respect to the surface normal. Surface excitations are considered for both sides of a solid–vacuum interface when an electron is incident on or emitted from a surface. These SEPs represent not only the appearance of surface excitations but also the inhibition of bulk excitations. Four common SEP formulas are evaluated, and we present best-fit parameters for the most satisfactory formula. SEP can then be readily determined for about 22 materials and various energies and electron incidence or emission angles. Copyright © 2012 John Wiley & Sons, Ltd.

In semiconductor industry, strict critical dimension control by using a critical dimension scanning electron microscope (CD-SEM) is an extremely urgent task in near-term years. A Monte Carlo simulation model for study of CD-SEM image has been established, which is based on using Mott's cross section for electron elastic scattering and the full Penn dielectric function formalism for electron inelastic scattering and the associated secondary electron (SE) production. In this work, a systematic calculation of CD-SEM line-scan profiles and 2D images of trapezoidal Si lines has been performed by taking into account different experimental factors including electron beam condition (primary energy, probe size), line geometry (width, height, foot/corner rounding, sidewall angle, and roughness), material properties, and SE signal detection. The influences of these factors to the critical dimension metrology are investigated, leading to build a future comprehensive model-based library.

above 70 o . The present simulation results then suggest that for the inelastic mean free path measurements the emission angle should be below 70 o in an EPES experiment to reduce the roughness effect. Copyright © 2012 John Wiley & Sons, Ltd.

A spin-involved Monte Carlo simulation model is developed to study the mechanism of the spin polarization of secondary electrons. The spin-dependent mean free path asymmetry and the Stoner excitation are considered in modeling electron inelastic scattering, and the spin-dependent excitation mechanism of cascade electrons is introduced according to the spin density of the state of a magnetism sample. The simulation has been performed for Ni and Fe. The simulated results, including secondary electron yields, secondary electron energy spectrum, and spin polarization of secondary electrons, are in good agreement with experimental results. According to the present simulation results, it is concluded that the high spin polarization of secondary electrons less than approximately 5 eV is inherently related to the cascade production process of secondary electrons; a more obvious effect of Stoner excitation is found for Ni but not for Fe because of the lack of unoccupied 3d states for spin-majority electrons above the Fermi level for Ni. We have further studied the case that an unpolarized thin layer exists on Fe surface; the results show that the spin polarization of secondary electrons can be greatly affected at low primary energies. Copyright © 2012 John Wiley & Sons, Ltd.

Diatoms are unicellular microscopic organisms with silicon dioxide-based cylindrical-shaped skeletons, enveloped with an organic material composed of essentially polysaccharides and proteins. By removing the organic compounds from the diatom, we present an alternative method for the preparation of insulating nanocapillaries. The lengths of the capillaries are about 100 µm and the diameters of the regularly structured pores are about 200 nm. Moreover, we confirm with measurements by XPS that the shell of the Pennales diatoms contains mostly SiO2 .C opyrightc � 2008 John Wiley & Sons, Ltd.

Summary: The fractal behavior of electron scattering in solids, simulated by the Monte Carlo method, has been studied. The trajectories of electrons of 1‐10 keV primary energies in Si, Cu, Ag, and Au have been simulated. The Hausdorff dimensions of trajectories of primary electrons, trajectories of primary electrons plus secondary electrons, and spatial distributions of secondary electron birth sites have been determined by the box-counting method. The fractal geometry can be used to describe quantitatively the complexity of the electron scattering process in solids.

The electron inelastic scattering in silver is studied both experimentally and theoretically. The reflection electron energy loss spectroscopy (REELS) spectra were measured using the ESA-31. It is shown that the surface excitation is enhanced with decreasing primary energy. For the higher resolution spectra with the narrower energy distribution of elastically scattered electrons, the Tougaard’s recursive formula describes inelastic scattering cross section from the measured energy loss spectrum as well as the extended Landau approach. At low primary energies, the differential inverse inelastic mean free path (DIIMFP) for low loss energies extracted by Tougaard’s recursive method is smaller than that by the extended Landau approach. The latter method is better for measured REELS spectra with a large full width at half maximum (FWHM) of elastic peak (e.g. for a CMA). The effective energy loss function (EELF) has been derived from these experiments based on the extended Landau approach. The Monte Carlo simulated REELS spectra with the derived EELF agree well with the experimental spectra. Copyright  2006 John Wiley & Sons, Ltd.

A Monte Carlo model has been developed to study the spin polarization of secondary electrons emitted from magnetic materials. The spin direction of the generated secondary electrons is considered, and the spin-dependent inelastic mean free paths for spin-up and spin-down electrons are introduced to trace the secondary electrons in the simulation. Good agreement with respect to the energy distribution, including the enhancement at low energy and fine structure at higher energies in the secondary electron energy regime, can be found between the simulated polarization and the experimental data. The simulated primary energy dependence of the spin polarization is also found to agree reasonably well with the experimental data.

For a surface localized nano-structure, the XPS quantification based only on peak intensity analysis is inaccurate. In this work, we have developed an algorithm that is more elaborate and convenient for application to XPS quantification of nanoscale thin film on substrate by considering the background in a region of about 100eV following the film signal peak. A W/SiO 2 overlayer sample is investigated in this work. Theoretical evaluation of the spectra is compared with the experimental result and a pertinent algorithm is derived for application to the film thickness analysis.

We have studied the effect of elastic scattering and analyser geometry on calculations of electron escape depths. A theoretical analysis of the electron escape depth has been presented that shows how it is related to the solid angle for detection and the geometrical configuration of a cylindrical mirror analyser. To estimate the extent to which elastic scattering can modify the values of the escape depth, Monte Carlo simulations of the emission of Auger electrons were carried out for Cu MVV (59 eV), Cu LMM (916 eV), Au NVV (238 eV) and Au MNN (2025 eV) signals. From the calculated depth distributions of signal electrons, we have derived a correction factor for the electron escape depth in terms of the corresponding inelastic mean free path which includes both the effects of elastic scattering and analyser geometry. We have found that elastic scattering reduces the value of the escape depth by several tens of per cent and, depending on the target, signal electron energy and analyser geometry, the ration between the escape depth and the inelastic mean free path varies from 0.4 to 0.6.