bluuebunny/crossref_metadata_2025_split huggingface dataset:
The inelastic mean free path of electrons in some semiconductor compounds and metals
Authors: Jablonski A. , Mrozek P. , Gergely G. , Menhyárd M. , Sulyok A. 
Published: May 2005

AbstractThe elastic backscattering probability Pe of electrons is proportional to the product of the inelastic mean free path (IMFP), effective backscattering cross section (σeff), and atomic density (N). Thus, experimental evaluation of Pe, e.g. from the elastic peak intensity measurements, enables the determination of the IMFP. σeff can be calculated by integrating the differential elastic scattering cross sections using a simplified model based on the first Born approximation and the Thomas–Fermi–Dirac atomic potential. No significant difference in the values of σeff was found using the Thomas–Fermi, the Thomas–Fermi–Dirac and the Hartree–Fock atomic potentials or integrating the scattering cross sections tabulated by Fink et al. From the experimental values of Pe reported by Schmid et al. and by Gergely the IMFP was determined for a number of elements. A good agreement was found with the data on the IMFP published in the literature. Comparing the elastic peak of two samples and using the data of Ashley and Tung as reference values, the IMFP has been determined for GaP, GaSb, InP, InSb and Si3N4 samples. Good agreement with the data of Ashley and Tung was obtained for Si, Ge, SiO2 and GaAs.
Ionicity of metallic oxide surfaces on metals as observed by Auger (XPS) spectroscopy
Authors: Ascarelli P. , Moretti G. 
Published: May 2005

AbstractResearch relevant to the understanding of polymer–metal adhesion led us to an oxygen Auger (KLL) study on metal oxide surfaces. This was done in order to analyse the ionicity and strength of ‘Lewis sites’ on oxide surfaces grown on metals as compared to their bulk metal oxide counterparts. Following some suggestions contained in earlier works by Wagner we show that relative Auger (KLL) oxygen energies are a sensitive probe of oxygen valence electron population and hole relaxation. A semi‐empirical model is discussed to justify these findings. Furthermore it is shown that this ‘observable’ feature is also influenced by the metal oxide thickness at the metal surface.
Facet development and its influence on depth resolution during sputtering of Si
Authors: Carter G. , Nobes M. J. , Abril I. , Garcia‐Molina R. 
Published: May 2005

AbstractA model is developed, assuming mutation of facet lengths to larger values, to explain the experimental observations of the change in the population distribution of the lengths of facets developed during ion bombardment sputtering erosion of Si. The ensuing Gaussian facet length distribution, with mean length increasing linearly with ion fluence, is then used to show that the depth resolution δz/z0 of interface broadening first increases as z and then tends towards a constant value with increasing z0.
Energy calibration secondary standards for X‐ray photoelectron spectrometers
Authors: Evans Stephen 
Published: May 2005

AbstractThe selection of elementary calibration standards for X‐ray photoelectron spectrometers is discussed; it is suggested that Zn and Ga may be more satisfactory routine single‐element standards than Cu, Ag or Au. Binding energies for the 2p3/2 and 3d photoelectron peaks from elemental Zn, Ga (and Ge) and for the most intense LMM Auger peaks from Zn and Ga are reported and relevant energy separations compared with published Lα X‐ray energies. The instrumental voltage scale was calibrated to a precision of 0.0035% (one standard deviation, SD) by reference to published data for Cu and Au and the SD of the measured peak energies were generally ⩽0.03 eV. Taking residual voltage scaling uncertainties into account, the largest energy separations in the data for Zn and Ga should be accurate to 0.05 eV (one SD).
Results of an ISS round robin sponsored by ASTM committee E‐42 on surface analysis
Authors: Miller A. C. 
Published: May 2005

AbstractResults are reported for a round robin involving ion scattering peak positions and FWHM measurements from seven cylindrical mirror analyzer (CMA) based instruments from the same manufacturer. The specimen used in the round robin was a Cu–Ag–Au ternary alloy. The ion scattering data were obtained using 4He and 20Ne ions at 1 and 2 keV. Within the set of data for any given peak, the spread in the FWHM values was >70%, and the variation between the maximum and minimum CMA voltages was ∼8.5% A comparison of the experimental data with the results of calculations involving the dispersion characteristics of a CMA and the scattering equation suggests that much of the spread in the peak position is associated with the position of the specimen with respect to the CMA geometry. The cause of the spread in the FWHM measurements is unknown. Further analysis of the data indicates an inelastic energy loss of ∼3% for 20Ne scattering from Ag at 2 keV.
Convolutional smoothing algorithms in electron spectroscopy
Authors: Evans Stephen , Hiorns Anthony G. 
Published: May 2005

AbstractMultiple application of the convolutional smoothing algorithm of Savitsky and Golay to electron spectra leads to an undesirable distortion of the lineshape. The use of a single convolution of the data with a suitably‐chosen Gaussian function gives superior results with a large saving in computation. The distortion introduced by this procedure merely simulates the effect of widening the spectrometer slits.
The use of an electron flood gun when adopting monochromatic AgLα radiation for the XPS analysis of insulators
Authors: Edgell M. J. , Paynter R. W. , Castle J. E. 
Published: May 2005

AbstractTo combat the problem of specimen charging when analysing insulators with a high energy monochromatic AgLα x‐ray source for XPS in the VG ESCA3, the application and use of a low energy electron flood gun is investigated. It is found that individual specimens can require widely differing ‘optimum’ conditions for the satisfactory management of surface charging. However, the use of an accelerating voltage of at least 6 V, together with an emission current of at least 0.25 mA, appears to be satisfactory for the majority of specimens. It is concluded that an electron flood gun, when properly set‐up, can play an important role in gaining chemical state information from non‐conducting materials using XPS, though it is noted that the use of secondary binding energy referencing may still be necessary.
Analysis of polymer surfaces by SIMS 6—detection of cyclic oligomer on the surface of poly(ethylene terephthalate) film
Authors: Briggs D. 
Published: May 2005

AbstractThe dominant oligomeric species in poly(ethylene terephthalate) (PET) is cyclic trimer. Comparison of the SIMS spectra of pure polymer and cyclic trimer shows a markedly more intense peak at 577 daltons in the positive ion spectrum from the trimer, since this is the mass of the quasi‐molecular ion. This difference can be used to semi‐quantitatively analyse for cyclic trimer which has migrated to the surface of PET film.
An AES/SEM study of reed blades
Authors: Vanden Berghe R. , Vlaeminck R. , Van Paemel R. , Saillé M. 
Published: May 2005

AbstractThe soft Reed consists of two Au coated Fe/Ni blades sealed in a glass tube filled with nitrogen. The desired properties of the contact area of the Reed blades (hardness, contact resistance etc. …) can be obtained either by diffusion‐annealing (in vacuum or in an inert atmosphere) or by ‘arcing’ and ‘furbishing’. In this paper the compositional changes of the contact layer, resulting from diffusion annealing are related to the annealing time and temperature, and compared with those obtained by ‘arcing’ and ‘furbishing’. Arcing and furbishing are performed in the sealed Reed switch in which a glow discharge is ignited by applying an alternating tension between the blades, first when the blades are stationary, without making contact (arcing), and second when the switch is activated intermittantly (furbishing). The modifications of the surface composition, due to arcing and furbishing are compared with those obtained by annealing in nitrogen or in nitrogen/oxygen mixtures. A possible relation between the surface composition of arced and furbished Reed switches and the measured contact resistance is examined. These investigations are performed using SEM and AES techniques.
Surface studies of keratin fibres and related model compounds using ESCA, 2—intermediate oxidation products of cystyl residues on keratin fibre surfaces and their hydrolytical stability
Authors: Baumann H. , Setiawan L. D. , Gribbin D. 
Published: May 2005

AbstractS 2p binding energies of the surfaces of keratin fibres oxidized to different degrees under industrially applied oxidative wet finishing conditions have been estimated using ESCA. With the help of S 2p data obtained from chosen model compounds qualitative identification of the oxidation products of cystyl residues on the surfaces of partially oxidized wool has been made. The oxidation products identified are the residues of cystine monoxide, cysteine sulphinic acid and sulphonic acid. The hydrolytical stability of the intermediate oxidation products of cystyl residues on the fibre surface seems to be comparable with that of the model compounds (cysteine sulphinic acid>cystine monoxide>cystine dioxide). The reaction conditions determine the partial oxidation products which are analysed on the fibre surface. However, in the present study a conclusive evidence for the existence of dioxycystyl residues cannot be given.
Practical surface analysis: state of the art and recent developments in AES, XPS, ISS and SIMS
Authors: Hofmann Siegfried 
Published: May 2005

AbstractThis review considers the well established and most frequently applied surface analysis techniques: AES, XPS, ISS and SIMS in a comparative manner, confronting fundamental principles and present instrumental performance with the requests of the scientist. The primary goal of surface analysis is the determination of the elemental composition of the outermost atomic layer of a solid. In addition, characterization of binding states, of homogeneity and of structural details will often be required. Whereas the information gathered generally contains also contributions from deeper layers, the inherent high in depth resolution of the techniques allows thin film analysis with high precision. Thus, surface analysis includes the analysis of interfaces and thin films by depth profiling. Recent progress has led to improvements e.g. in sensitivity, spectral resolution and data acquisition and handling. With the trend to high spatial resolution, surface analysis is becoming a special branch of microlocal analysis. Quantification is of primary interest. However, the variety of approaches and their dependence on instrumental parameters hamper interlaboratory comparisons, pointing out the need of standardized methods and correction procedures, of well characterized test samples and of accurate data banks. Advance in precise quantification will depend on future progress in our understanding of matrix effects and beam‐sample interactions.
Distribution of hydrogen in the NPL standard ta2O5 films
Authors: Bishop H. E. 
Published: May 2005

AbstractThe NPL has produced well characterized tantalum pentoxide anodized films for use as a thickness and depth resolution standard for profiling in surface analytical techniques. Very sharp interfaces for these films have been demonstrated using AES. Studying these films by dynamic SIMS in the CAMECA IMS 3F, well defined profiles with a sharp interface were obtained with an oxygen primary beam. More complex profiles were obtained with argon and caesium primary beams, apparently showing the presence of hydroxide at the metal/oxide interface and a high concentration of hydrogen in the metal near the surface. However an argon primary beam with an oxygen flood gave the same type of profile as that obtained with an oxygen primary beam. Elastic Recoil Detection Analysis confirmed that there was no high concentration of hydrogen at the metal‐oxide interface and showed that hydrogen in the tantalum was present at 1 at %.
XPS and ISS examinations of electrode surfaces and passive layers with a specimen transfer in a closed system
Authors: Haupt S. , Calinski C. , Collisi U. , Hoppe H. W. , Speckmann H.‐D. , Strehblow H.‐H. 
Published: May 2005

AbstractThe application of UHV surface analytical methods to the study of electrodes and surface layers may be affected by changes introduced by contact with the laboratory atmosphere. Therefore, a specimen preparation and transfer in a closed system with its specifications is described. Three examples of its application are discussed: the examination of the electrode – electrolyte interface on Cu and the study of the formation of passive anodic oxides on Fe and on FeCr alloys in 1 M NaOH.
Ion scattering spectroscopy studies of zirconium dioxide thin films prepared in situ
Authors: Martin P. J. , Netterfield R. P. 
Published: May 2005

AbstractLow energy ISS has been used to investigate, in situ, thin films of zirconium dioxide deposited by evaporation and ion‐assisted deposition. It is shown that when a film is deposited to an average thickness of 0.3 nm ± 0.03, as measured by in situ ellipsometry, complete coverage of the substrate occurs. Ion‐assisted films have detectably higher Zr surface concentrations and reduced low‐energy sputter peaks. Inelastic tailing effects in the Zr scattering peak for 2 keV 4He+ are found to come from particles scattered from approximately the first 7 nm of the oxide surface. The influence of primary ion energy on the Zr/O ratio is also examined.
Angle‐resolved X‐ray photoelectron spectroscopy of epitaxially grown (100) β‐SiC to 1300 °C
Authors: Wheeler Donald R. , Pepper Stephen V. 
Published: May 2005

AbstractThe (100) surfaces of three β‐Sic crystals grown epitaxially on Si substrates were analyzed by angle‐resolved x‐ray photoelectron spectroscopy (XPS). The specimens were heated by direct current for 2 min in 25 °C increments from 900 to 1300 °C. After each anneal, Si 2p, C 1s and O 1s spectra were obtained for 28° and 64° photoelectron takeoff angles. After annealing below 1150 °C, the Si 2p spectrum has three main lines. One is assigned to SiC, one to SiO2 and the other to a suboxide. The angular dependence of the intensities of the three features is consistent with 22 A of SiO2 over 10 Å of suboxide on the SiC substrate. After annealing above 1150 °C, the O 1s and the oxide lines in the Si 2p spectrum gradually decrease, while the C 1s spectrum develops a second line which proved to be due to surface graphite. After heating at 1175 °C the surface was free of oxide and nearly free of graphite. For this surface, C 1s and Si 2p spectra were obtained for electron takeoff angles between 8° and 64°. Comparison of the Si 2p/C 1s ratio with that calculated from a layer model of β‐SiC indicates that the top layer in this state is primarily Si rather than C. After heating above 1200 °C, the second characteristic line in the C 1s spectrum grows. Both the binding energy and characteristic loss features of the new carbon line developed after annealing at high temperatures indicate that it is due to graphite. The angular dependence of the intensities of the two C 1s features indicate that 18 Å of graphite is formed on the surface heated to 1300 °C for 8 min.
Energy spectra of electrons transmitted through aluminium films
Authors: Tung C. J. 
Published: May 2005

AbstractThe transmission of electrons through aluminium films has been studied. Several physical quantities including the energy loss, the pathlength, the angular deflection and their distributions were calculated. Theoretical models have been used to estimate the inelastic and elastic differential cross‐sections for electrons in aluminium. The calculated spectra were compared with available experimental data.
Modification of the electrical and mechanical properties of AlGaAs interfaces induced by low energy electron irradiation
Authors: Gazecki J. , Williams J. S. , Cozzolino C. 
Published: May 2005

AbstractChanges in the AlGaAs Schottky characteristics after low energy (20 keV) and low fluence (<1017 cm−2) electron irradiation have been investigated and correlated with film adhesion enhancement which also results from electron bombardment. The electrical and mechanical characteristics were measured as a function of irradiation dose. The observed lowering of the barrier height after irradiation can be related to an induced positive charge in the interfacial layer. It is suggested that this positive charge may be partly responsible for the adhesion enhancement of the Al film to the GaAs substrate.
Quantitative AES study of Fe/P alloys using a calibration curve after fracture in UHV
Authors: Hirokawa Kichinosuke , Oku Masaoki 
Published: May 2005

AbstractQuantitative AES is commonly used in the field of surface analysis. It has been found for Fe/P alloys that when appropriate references for a calibration curve could be obtained, quantification could be carried out with interesting metallographical information.
Investigation of a passive film on an ironchromium alloy by AES and XPS
Authors: Mischler S. , Mathieu H. J. , Landolt D. 
Published: May 2005

AbstractPassive films formed on a Fe24Cr alloy in 0.5 M H2SO4 at 0.7 V are characterized by AES depth profiling and XPS. Obtained results and evaluation procedures are critically compared. It is found that correction for electron escape depth significantly improves the accuracy of AES profile data. The use of low energy peaks in AES allows metallic species to be distinguished from oxidized species and profiles with good depth resolution to be obtained. Quantification is impeded by peak overlap. XPS results depend significantly on the background subtraction and peak deconvolution procedure employed. From the different data it is concluded that the ratio Cr/Cr + Fe in the passive film studied is approximately 0.9 compared to 0.26 for the bulk alloy. The film thickness is 1.5 ± 0.3 nm. Within the precision of present XPS data the metal composition of the layers adjacent to the film is the same as that of the bulk.
Quantitative analysis of the inelastic background in surface electron spectroscopy
Authors: Tougaard Sven 
Published: May 2005

AbstractRecent progress, in the quantitative analysis of the distortion of surface electron spectra, resulting from inelastic electron scattering, is reviewed.A physical model for the problem is formulated and based on this, basic deconvolution formulae are found. In the formulae, detailed information on the differential inelastic electron scattering cross‐section K is essential. Methods to determine,K are studied and developed. One method is based on a dielectric response calculation. Furthermore, it is found that for the noble and transition metals, K is sufficiently similar that a simple ‘universal’ cross‐section can be defined. In addition, methods for experimental determination of cross‐sections are found and in particular a formula is derived which allows the extraction of direct quantitative cross‐section information through a simple analysis of REELS spectra.The importance of proper background correction is investigated for model electron spectra. Experimental XPS spectra are also studied and it is found that for both the simple and the noble metals, the primary excitation spectra extend 2–3 inelastic scattering events, i.e. ∼50 eV, below the peak energy. Beyond this energy, the spectra are of zero intensity over a wide energy range. Besides, experimental spectra are analysed on the basis of experimentally determined cross‐sections and the results are discussed, in relation to the analysis based on theoretical cross‐sections.The importance of defining simple procedures for routine analysis of spectra is stressed and it is demonstrated that the proposed ‘universal’ cross‐section provides a very simple method for approximate spectral analysis.Finally, some important issues to be considered in the near future are pointed out.
XPS studies of the thermal behaviour of passivated Zircaloy‐4 surfaces
Authors: Kaufmann R. , Klewe‐Nebenius H. , Moers H. , Pfennig G. , Jenett H. , Ache H. J. 
Published: May 2005

AbstractThe composition and the chemical states of components of Zircaloy‐4 (zirconium alloy) surfaces were studied in the temperature range between room temperature and 500°C. Each sample was kept at constant temperature (25, 100, 200, 300, 400, 500°C) for up to 16 hours. The changes of composition and chemical states of the Zircaloy‐4 surface during heating were monitored by x‐ray photoelectron spectroscopy (XPS). Originally, the components form well‐defined layers elucidated by angle‐resolved x‐ray photoelectron spectroscopy (ARXPS). In contrast to depth profiling using ion sputtering, ARXPS is non‐destrutive. However, it is applicable for layers of up to a few nanometres thickness only.The experiments showed a decomposition of the ZrO2 coverage above 200°C accompanied by oxygen diffusion into the bulk. These processes lead to the reduction of ZrO2 to metallic zirconium on the surface at 300°C and higher temperatures. The oxygen diffusion into the bulk was indicated by AES depth profiles. The layered structure observed up to a heating temperature of 200°C could not be seen at higher temperatures. After Zr metal appears at the surface during the heating process, a reaction with the adsorbed hydrocarbons takes place, leading to the formation of zirconium carbide.Though the depth resolution of an AES depth profile does not permit identification of layers with thicknesses in the nanometre region, the temperature‐dependent behaviour of oxyen is reflected by its AES profiles, showing features in accordance with the results from ARXPS, especially with respect to the fact that well‐defined layers vanish above 200°C.
Characterization of silica overlayers deposited on ZrO2 and TiO2 by CVD of Si(OC2H5)4
Authors: Jin T. , White J. M. 
Published: May 2005

AbstractSilica, derived from Si(OC2H5)4, was studied on high surface area titania and zirconia powders using ion scattering spectroscopy (ISS) and Auger electron spectroscopy (AES) with depth profiling. After a large exposure and thermal processing of Si(OC2H5)4, more silicon was detected by AES on TiO2 (Si/(Si + Ti) = 50%) than on ZrO2 (Si/(Si + Zr) = 40%). With ISS, however, the reverse was found; the Si signal was 92% of the total metal on ZrO2 but only 70% on TiO2. Moreover, when the silica‐covered oxide surfaces were depth‐profiled with Ar+ (2 kV, 4 μA), the fraction of silica, based on ISS, decreased rapidly from 92% to 55% during the initial 100 s for ZrO2 but remained about 70% over the first 150 s for TiO2. The results strongly support a model in which Si(OC2H5)4 decomposes to form a thin film of SiOx which completely covers ZrO2, while on TiO2, particles of SiOx and/or mixed oxide layers form which leave titania exposed. On ZrO2, the estimated thickness of the SiOx film is 0.24 nm.
Combined EBIC—Auger analysis of AuGeNi/n‐GaAs ohmic contact formation
Authors: Hill I. R. , Lau W. M. , Yang G. R. , North R. A. 
Published: May 2005

AbstractElectron beam induced current imaging has been used to monitor the dynamic changes of the metal–semiconductor interface of AuGeNi/n‐GaAs during annealing at 300°C. The reacted interface was then revealed by argon ion etching of the metal overlayer, and analyzed by secondary electron and Auger electron imaging. The combined EBIC–Auger imaging of the reacted interface indicates that the formation of the ohmic contact starts at localized areas where small Ni‐ and As‐rich grains are formed. The results also show that this combined EBIC–Auger imaging technique is particularly suitable for investigating the mechanism of degradation of Schottky contacts.