bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thickness dependence of the characteristic X‐ray yield and the Auger backscattering factor
Authors: Ei Gomati M. M. , Ross W. C. C. , Matthew J. A. D. 
Published: May 2005

AbstractA Monte Carlo model employing a screened Rutherford scattering cross‐section and the Bethe energy loss approximation has been used to investigate the thickness dependence of the backscattering coefficient, η, the depth distribution of inner shall ionization, ϕ(ρz), the surface ionization function, ϕ(0), the Auger backscatter factor, r, and the initial gradient of the ϕ(ρz) curve, dϕ(0)/dz. Backscatter coefficients obtained for thick samples are in good agreement with experiment with experimental values. The surface ionization functions for C, Al, Cu, Ag and Au display an S‐shape thickness dependence, which is explainable in terms of the different scattering behaviour for samples of high and low atomic number. A direct relationship between the normalized surface ionization function, ϕ(0), and the Auger electron backscattering enhancement factor, r, is found, and a preliminary investigation has been made into the target thickness dependence of dϕ(0)/dz.
SIMS profile simulation using delta function distributions
Authors: Clegg J. B. , Gale I. G. 
Published: May 2005

AbstractSIMS profiles of abrupt dopant distributions in semiconductor materials contain distortions introduced by the measurement process. In quantitative depth profile studies, it is important to determine and remove these errors.We have used the idea that a given input profile may be represented by a series of adjacent delta‐doped planes. Given a knowledge of the SIMS obtained form one single plane (the resolution function), it is possible to simulate the expected SIMS profile form a given input profile by the convolution with the resolution function. Experimental data have been obtained form special samples of molecular beam epitaxial GaAs containing both delta‐doped planes and uniformly doped regions (1–20 nm thick). The dopants investigated were Si, Be and Al. It is shown that the simulated and experimental profiles of the uniformly doped regions show good agreement, thus demonstrating the validity of the method. We also present results of the convolution of an input function having exponential decays on the leading and trailing edges, which show the corrections that should be made to experimentally determined profiles. Additional simulations have been made with Gaussian inputs, which are relevant in dopant diffusion studies, Silicon diffusion lengths as small as 4 atomic planes (1.1 nm) have been deduced.
Quantitative resolution of X‐ray photoelectron spectra of mixtures of chromium compounds by the Kalman filter after cubic spline background removal
Authors: Malitesta C. , Rotunno T. 
Published: May 2005

AbstractThe potential of a new procedure for the quantitative analysis of ESCA spectra was exploited by determining the composition of powder mixtures of some chromium compounds. The quantitative separation of the overlapped Cr 2p peak doublets was accomplished by the Kalman filter algorithm. Background removal from the spectra was carried out by a new approach employing the cubic splines as smooth interpolators between the peak valleys. The results of the analyses compared well with those obtained by factor analysis (typical errors were ±4%). However, the Kalman filter operating recursively on the data points of the spectrum is preferable when the analysis is limited to only one mixture plus standards. Cubic spline interpolation was as effective as the Shirley method in yielding quantitative background subtraction.
XPS and SIMS studies of biodegradable suture materials
Authors: Brinen J. S. , Greenhouse S. , Jarrett P. K. 
Published: May 2005

AbstractXPS and SIMS have been used to examine the surface composition of copolymers of glycolide (cyclic dimer of glycolic acid) and trimethylene carbonate (TMC) as solvent‐cast films. XPS results on the polymers agree with bulk composition data. SIMS measurements suggest surface enrichment of the TMC component.
A novel practical approach to the quantification of Auger electron spectroscopy
Authors: Mischler S. , Bishop H. E. 
Published: May 2005

AbstractWe describe here a novel practical approach for the quantification of AES based on normalization of the peak height to the background measured at a fixed energy.Studies from the literature show that the background has an angular dependence close to the for the AES peak and it is directly proportional to the primary electron current. In addition, we have found that for a primary beam energy of 10 keV the background measured at 2 keV exhibits practically the same atomic number dependence as the back‐scattering factor. Therefore, we have proposed that normalization of the peak height to the background allows us to determine the absolute surface concentration of an element without reference to the other elements present, provided that the mean free path is known.This proposal has been tested buy making measurements on a range of oxides, silicon compounds and metals. A good correlation is found between the O KLL peak‐to‐background ratio and the atomic concentration of oxygen in a series of oxides covering a wide range of atomic number (Mg to U). A similarly good correlation is observed for magnesium, silicon, iron and nickel Auger peaks.The physical basis and the limitations of this quantitative approach are discussed.
Composition of thin surface layers obtained by X‐ray photoelectron spectroscopy
Authors: Watton H. L. L. , Fitzgerald A. G. , Moir P. A. 
Published: May 2005

AbstractThe surface composition of a solid may vary considerably from the bulk composition of the material. For example, surface contaminants such as carbon, oxygen, sulphur and chlorine can be present as a thin overlayer. Recently, procedures have been developed that enable determination of the composition, thickness and surface coverage of a thin overlayer on a surface from AES spectra. In the present work, a similar procedure has been developed for analysis of thin overlayers by XPS. The calculation deals with two possible situations, the overlayer either does or does not contain elements that occur in the underlying material. The composition, thickness and surface coverage of a number of overlayers have been investigated, including the surface contaminant layers on amorphous silicon films, a series of amorphous silicon nitride films with varying atomic ratios of silicon and nitrogen and vacuum‐deposited gold films on amorphous silicon nitride substrates.
Detection limits of surface contamination analysis by nitrogen‐RBS
Authors: Weidhaas Jens , Lang Walter 
Published: May 2005

AbstractOwing to the development of thin‐film, semiconductor and clean‐room technologies, there is an increasing demand for the measurement of trace elements on surfaces. Rutherford backscattering spectroscopy using nitrogen ions is a powerful tool for this purpose. For heavy elements, e.g. gold, in silicon a surface sensitivity of 1010 atom cm−2 is reached. For medium elements, e.g. As, Cr and Fe, the detection limit is at 1012 atom cm−2.
Application of surface analysis techniques to the study of paint/metal interfaces related to adhesion and corrosion performance
Authors: van Ooij W. J. , Sabata A. , Appelhans A. D. 
Published: May 2005

AbstractInterfaces between galvanized steel and automotive cathodic electrocoat paint systems were characterized by imaging XPS and static SIMS, using time‐of‐fight SIMS and quadrupole SIMS with an SF6 primary source. Variables were the pretreatment of the metal (phosphate coating) and the cure state of the pain system. Analyses were carried out prior to and following exposure in an accelerated cyclic corrosion test. In systems without phosphate pretreatments, severe delamination was observed in non‐corroded areas. In such areas, zinc hydroxycarbonate was found at the interface. In corroded areas, adhesion was retained, probably as a result of an interaction between cathodically generated O− ions and the paint. In phosphated systems, an undercure of the paint led to an increase of the underfilm corrosin. Static SIMS analysis of the paint/metal interface demonstrated that the state of cure of cathodic electrocoat systems can be detected by this technique and, furthermore, that certain paint constituents are preferentially adsorbed on the metal surface. The degree of cure of the paint was shown to change in going from the air/paint surface to the buld and on to the paint/metal interface. The adhesion behaviour of epoxy electrocoat systems to metallic substrates can be described in terms of acid–base interactions.
Non‐destructive characterization of polymer/metal interfaces using surface‐enhanced Raman scattering
Authors: Boerio F. J. , Hong P. P. , Tsai H. W. , Young J. T. 
Published: May 2005

AbstractSurface‐enhanced Raman scattering (SERS) is an analytical technique in which the Raman scattering cross‐sections of molecules absorbed onto the roughened surfaces of certain metals are enhanced by as much as six orders of magnitude compared to their value for normal Raman scattering. The mechanisms are associated with the large electric fields that can be induced at the surfaces of metal particles having small radii of curvature and with the formation of charge‐transfer complexes between the adsorbed molecules and the substrate. Enhancement due to the charge‐transfer mechanism is obtained only for molecules immediately adjacent to the surface, but enhancement due to the electromagnetic mechanism may extend several monolayers away from the surface. Since normal Raman scattering by polymers is weak and scattering by molecules adjacent to the substrate is strongly enhanced, SERS can be used for non‐destructive characterization of interfaces between polymer films and metals as long as the films are not so thick that scattering by the bulk of the film is comparable in intensity to SERS from the interface.We have used SERS to examine the interface between silver and an acrylic adhesive system consisting of an acrylic monomer and a cure system comprising cumene hydroperoxide (CHP), acetylphenylhydrazine (APH) and saccharin. SERS spectra obtained from films of the adhesive spin‐coated onto silver island films were similar to normal Raman spectra of salts of saccharin, indicating that saccharin had adsorbed on the silver dissociativly. The spectra were independent of the thickness of the adhesive films, indicating that the SERS signal was characteristic of the interface and not of the bulk adhesive.SERS has been used also to characterize the interface between silver and pyromellitic diimide (PMDI), a model compound for polyimides. SERS spectra of PMDI adsorbed onto silver were considerably different from normal Raman spectra. The strongest band in the normal spectra, a carbonyl stretching mode near 1770 cm−1, was absent from the SERS spectra and a band near 700 cm−1, which was very weak in normal Raman spectra, was strong in SERS spectra. It was concluded that PMDI was adsorbed in a vertical conformation with one imide group adjacent to the surface.
XPS studies of the bonding and hydrolysis of dentine bonding agents
Authors: Williams R. L. , Ali S. A. M. , Williams D. F. 
Published: May 2005

AbstractX‐ray photoelectron spectroscopy has been used to analyse the surface chemistry of dentine, the surface coverage of dentine by an experimental dentine bonding agent and the commercially available gluma Bond system and the hydrolysis of these adhesives. The cut dentine surface is shown to be of high inorganic composition. When this surface is treated with ethylenediaminetetracetic acid, the inorganic component was significantly reduced. The two adhesives were shown to spread effectively on the treated dentine surface and, following incubation in an aqueous environment, neither bonding system appeared to exhibit significant hydrolysis.
Background removal in AES; influence of detection geometrical characteristics
Authors: Rosenberg N. , Tholomier M. , Vicario E. 
Published: May 2005

AbstractIn order to remove the inelastic background from Auger spectra, we took advantage of theoretical work assuming an experimental arrangement corresponding to cylindrical symmetry. The knowledge of the inelastic differential cross‐section K(T) is necessary for the background calculation (T is the energy loss), so we calculated K(T) from back‐scattering spectra experimentally obtained using either a cylindrical mirror analyzer (cylindrical symmetry) or a hemispherical mirror analyzer (no cylindrical symmetry). The strict application of theoretical expressions may eventually lead to a K(T) function with some negative part, i. e. without physical meaning. We have interpreted this effect and we consequently succeeded in eliminating any negative part. In setting out the Auger spectra background, we took into account secondary electrons created by Auger electrons by introducing distinct laws for the spectra from the two analysers. ‘Intrinsic’ Auger spectra, obtained from elemental materials (Si, Ag, Ni, Cu) andregistered from either analyzer, were compared. Some minor differences remain, according to which analyzer is used.
Study of the reduced In2O3/μc‐Si:H interface by means of factor analysis
Authors: de Nijs J. M. M. , Aarts R. G. K. M. 
Published: May 2005

AbstractThe overgrowth of an In2O3 layer by a μc‐Si:H layer, deposited by means of plasma‐enhanced chemical vapour deposition, will inflict the reduction of the In2O3. AES is combination with Ar+ depth profiling is used for the study of the interfacial deterioration that takes place. The results of a factor analysis study after reduction of the In2O3 are presented.
The Auger parameter, polarization energies and electronegativities: Application to a series of non‐conducting barium slats
Authors: Berrie C. L. , Langell M. A. 
Published: May 2005

AbstractBy use of the Auger parameter, we show that barium in a series of halogen and chalcogenide slats presents chemically distinct and identifiable states. Differences between Auger parameters are related to the ligand environment and can be used to obtain information on extra‐atomic relaxation, at lest some of which is non‐local in origin in this series of barium slats. As has previously been demonstrated by Moretti, non‐local contributions to the extra‐atomic relaxation correlate directly with nearest‐neighbor anion polarization energies. However, polarization energies are easily calculable only for simple distributions of identical ligands. We present an alternative correlation between the Auger parameter and electronegativity, which can easily be performed regardless of structural complications and which shows a high degree of precision.
Application of tandem analyser to SIMS studies of hydrocarbon polymers
Authors: Leggett G. J. , Briggs D. , Vickerman J. C. 
Published: May 2005

AbstractThe fragmentation of ions sputtered from the surface of low‐density poly(ethylene) (LDPE) has been investigated by studying their collisionally activated dissociation (CAD) when incident upon a variety of target gases in the collision cell of a triple quadrupole SIMS instrument. It was found that heavier targets resulted in more extensive CAD than was observed with lighter targets but that sulphur hexafluoride is inefficient target because of the amount opf energy that is transferred to its vibrational modes of motion (rather than being available to induce fragmentation in the parent ion.) The behaviour observed for an oxygen target was quite different to that observed for other targets (at higher pressures). In general oxygen induced markedly greater fragmentation for the small parent ions but xenon was the preferred target for the larger parent ions. Fragmentation patterns could readily be assembled for all of the parent ions observed in the SIMS spectrum of LDPE using the CAD data. There are good indications that the data obtained may assist in indentification of ion structures and in elucidation of general rules governing the fragmentation of organic materials during SIMS. For example, LDPE fragment ions were found to obey quite strictly the Even Electron Rule, a well‐known rule in mass spectrometry.
XPS Studies of characterized Cu/Al2O3, Zn/Al2O3 and CuZn/Al2O3, catalysts
Authors: Moretti Giuliano 
Published: May 2005

AbstractBy XPS it is confirmed that copper‐containing catalysts supported on alumina and calcined at high temperature (673–873 k for 24 h.), with or without zinc addition, have a ‘surface spinel’ structure.Combining the XPS results with previous results obtained by vis–UV reflectance spectroscopy and XRD we show that the limit of solubility of Zn and Cu ions in γ‐alumina, at a calcinations temperature of 873 k, about 20 and 10 wt.% (by weight), respectively. In the CuZn/Al2O3, catalysts prepared from Zn/Al2O3, a surface enrichment of copper occurs if the Zzinc ions are already presents in an amount larger than the surface solubility. The presence of zinc on the surface increases the reducibility under H2 of the Cu(II) ions compared to the same ions in the pure copper surface spinel. This may be due to the role of Zn(II)O(II) aggregates in the activation of the hydrogen molecule and/or to the segregation of CuO species on the Zinc surface spinel.
Spectroscopic cell for investigations of thin liquid films
Authors: Boinovich L. B. , Emel'yanenko A. M. 
Published: May 2005

AbstractA special cell for investigation of the alterations in the transmittance spectra of thin liquid films during their thinning has been designed. The cell described enables one to investigate liquid interlayers with thicknesses from 10 nm to a few microns. A method for the evaluation of thicknesses of film according to the transmittance spectra has been developed.
Characterization of a thin copper film to investigate microbial biofilm formation
Authors: Bremer Philip J. , Geesey Gill G. , Drake Barney , Jolley John G. , Hankins Michael R. 
Published: May 2005

AbstractCopper films, 6.7 nm nominal thickness, deposited by physical vapor deposition on germanium substrates appeared as coalescing aggregates of copper atoms when evaluated by atomic force microscopy. Evaluation of the Cu thin film by x‐ray photoelectron spectroscopy indicated that the Cu at the surface of the film had the character of a 1 + oxidation state. These features were not significantly changed when the Cu thin film was exposed to ethylene oxide. No Ge signal was detectable prior to XPS depth profiling through the Cu thin film, indicating that the film was continuous. When films of this thickness were deposited on a cylindrical Ge internal reflection element and subsequently submerged in an aqueous medium, there was sufficient transmission of infra‐red radiation through the Cu to obtain a significant water absorption band at 1640 cm−1. The intensity of the water absorption band was found to be very sensitive to changes in thickness of the copper thin film. This feature can be used to study the effect of microbial biofilms and their products on the integrity of oxidized copper surfaces in aqueous environments.
Angular intensity modulation in angle‐resolved XPC and AES of non‐crystalline ultrathin surface layers: The phenomenon and its implications
Authors: Gries W. H. 
Published: May 2005

AbstractThe well‐known phenomenon of forward (elastic) scattering of x‐ray photoelectrons and Auger electrons, which gives rise to prominent diffraction peaks for emission from monocrystalline materials, can lead to a much less prominent, yet significant, angular intensity modulation of emission from nominally non‐order materials in which stoichiometric or other constraints enforce some short to medium‐rang order. A seemingly small intensity modulation can have a drastic effect on the determination of layer thickness or of effective attenuation length from angle‐resolved measurements. This conclusion is arrived at by applying the known facts o forward scattering (summarized here) to the currently structural model of oxide layers on the semiconductors Si and GaAs (serving as examples). The predictions are compared with experimental data on carbonaceous contamination in the native oxide layers on Si (111) and GaAs (001), obtained by angle‐resolved XPS and AES and evaluated for angle‐dependent effective attenuation length. It is concluded that angular intensity modulation can be expected to be a frequently occurring phenomenon with serious implications for the study of ultrathin layers and ultraslow depth profiles by the electron spectroscopes XPS and AES.
AES depth profile study of a GaAs/AlAs superlattice
Authors: Kačiulis S. , Plešanovas A. , Tvardauskas H. 
Published: May 2005

AbstractThe width of the interface between sublayers in a GaAs/AIAs superlattice was investigated using AES combined with Ar+ ion sputtering and chemical etching. The factors stipulating the experimental broadening of the interface width were estimated. The real interface width, determined for a GaAs/AIAs superlattice grown by metal organic chemical vapour deposition (MOCVD), did not exceed three AIAs lattice constants. The influence of the sputtering ion beam energy to the experimental interface width, caused by surface roughness, was investigated. It was demonstrated that combination of the initial chemical etching or high‐energy ion sputtering with further low‐energy sputtering allowed deep sub layers to be investigated faster and without loss of depth resolution.
X‐ray photoelectron spectroscopy analysis of copper and zinc oxides and sulphides
Authors: Deroubaix G. , Marcus P. 
Published: May 2005

AbstractVarious copper and zinc compounds (Cu, Zn, CuZn alloy, Cu2O, CuO, Cu2S, ZnO, ZnS) have been synthesized and characterized by electron spectroscopy (XPS). Data on the 2p3/2 levels of Cu, Zn and S, the 1s level of O, the L3M45M45 Auger transitions of Cu and Zn, the valence bands and the modified Auger parameters are reported. The results obtained with these reference compounds allow qualitative and quantitative interpretation of XPS analyses on mixtures of these compounds.
Secondary ion mass spectrometry—first microelectronics, now the rest of the world
Authors: Stevie F. A. 
Published: May 2005

AbstractSecondary ion mass spectrometry (SIMS) has achieved great success as a materials characterization tool because of its parts‐per‐million to parts‐per‐billion sensitivity and excellent depth resolution. SIMS is best known for applications in the semiconductor industry, but is increasingly used in many other fields. Despite this growth, three myths persist regarding SIMS: the technique is not quantitative, insulators are difficult or impossible to analyze and good depth resolution cannot be obtained for metals. Recent work by several groups should dispell these misconceptions. Quantification with a reproducibility and accuracy of 10–20% is commonplace with ion implantation calibration methods. Patterns for secondary ion yields of the elements when plotted against ionization potential and electron affinity have been identified in a number of semiconductor and metal matrices. The pattern similarities allow sensitivity factors to be estimated for elements for which an implanted calibration is not available. The Lawrence Livermore project of selected elements into 200 matrices is expected to extend this concept to oxides, minerals, alloys, ceramics and fluorides. The analysis of insulators has been made routine by the use of an electron beam for charge neutralization and an understanding of the placement of the electron beam and the electron to ion current density ratio required. The glass industry provides many applications for this capability. Metals and other polycrystalline materials can be sputtered evenly if the sample is rotated during ion bombardment. This rotation method has been used for matrix‐level species in Auger analysis, and has now been shown to be viable in SIMS at the parts per million level.