bluuebunny/crossref_metadata_2025 huggingface dataset:
AES and XPS studies of surface films deposited during the plasma etching of silicon dioxide layers
Authors: Tuppen C. G. , Heckingbottom R. , Gill M. , Heslop C. , Davies G. J.
Published: May 2005

Surface films deposited during the selective plasma etching of SiO2 on Si by CHF3 have been studied using Auger electron spectroscopy (AES)2 and x‐ray photoelectron spectroscopy (XPS). The films have been subdivided into two types: ‘persistent’ and ‘non‐persistent’. Non‐persistent films could be etched in an oxygen plasma and consisted of a fluorocarbon polymer. The main components of persistent films (unreactive in an oxygen plasma) were oxygen and fluorine compounds of silicon with impregnated metal atoms sputtered from electrodes in the plasma etcher. The thickness of persistent films was found to depend on the electrode spacing and electrode material. This effect has been explained in terms of the ion sputtering inherent within the parallel plate plasma etching system.
Magnetron sputtered gold contacts on n‐GaAs
Authors: Buonaquisti A. D. , Matson R. J. , Russell P. E. , Holloway P. H.
Published: May 2005

DC planar magnetron sputtering has been used to deposit gold Schottky barrier electrical contacts on n‐type GaAs. The electrical character of the contact was determined from current‐voltage (I‐V) and electron‐beam‐induced voltage (EBIV) data. These data showed that the Schottky barrier height of magnetron sputter‐deposited contacts was lower than for vapor deposited contacts. The barrier‐height was a function of the deposition rate for electronically isolated substrates, and was dependent upon both the surface treatment prior to contact deposition, and upon doping density and post‐deposition heat treatment. These effects are discussed in terms of particle irradiation of the surface during contact deposition.
Secondary ion mass spectrometric analysis of leaching behaviour of magnesium from chrysotile in oxalic acid solution
Authors: Verlinden J. A. , De Waele J. K. , Swenters I. M. , Adams F. C.
Published: May 2005

A study was made on the dissolution kinetics of chrysotile asbestos in 0.1 N oxalic acid over the temperature range 0–80°C. After treatment, the fractional release of magnesium from the fibre was measured using secondary ion mass spectrometry. Diffusion coefficients were determined assuming a plane sheet model. It appeared that the Arrhenius relation is obeyed over the entire temperature range, with an activation energy of 72.1 kJ mole−1, in agreement with earlier literature data.
Ion‐bombardment‐induced changes in the surface topography of MBE‐grown silicon on gallium phosphide
Authors: Boudewijn P. R. , Akerboom H. W. P. , Bulle‐Lieuwma C. W. T. , Haisma J.
Published: May 2005

Ion bombardment of silicon layers grown by molecular beam epitaxy (MBE) or solid phase epitaxy (SPE) on top of GaP(100) substrates results in changes in the surface topography. The influence of the bombardment conditions on such topological features has been studied and the results are interpreted qualititively in terms of the angular dependence of the sputer yield. The consequences of pit formation for the reliability of the results from surface analytical techniques employing ion beam sputtering are discussed. The origin of bombardment‐induced surface roughening is ascribed to the presence of polycrystalline imperfections in the MBE or SPE‐grown silicon layer.
The measurement of the uptake of ions from solution by charged acrylic copolymers using XPS
Authors: Paytner R. W. , Castle J. E. , Gilding D. K.
Published: May 2005

XPS has been used to monitor the uptake of Na+ ions by p(acrylic acid/methyl methacrylate) and of Cl− ions by p(dimethylaminoethylmethacrylate/methyl methacrylate) from NaCl solution as a function of time and electrolyte concentration. The resulting changes in both the polymer and the solid/liquid interface are discussed in terms of the performance of these materials in the biological environment.
Characterization of silica‐supported uranium–molybdenum oxide catalysts
Authors: Fierro J. L. G. , Salazar E. , Legarreta J. A.
Published: May 2005

The techniques of X‐ray diffraction, infrared and electron spin resonance spectroscopies, kinetics of reduction by H2, and XPS were used to investigate the chemical species present at the interface in silica‐supported uranium–molybdenum oxide catalysts. In this catalyst series, with constant MoO3 loading (16.7 wt%) and Mo/(Mo + U) atomic ratios ranging between 1 and 0, it was found that the oxidic forms of Mo and U were not well dispersed, MoO3 crystallites being detected on the catalysts with a high Mo/(Mo + U) atomic ratio. In the less‐uranium‐rich catalysts [Mo/(Mo + U) = 0.89] both MoO3 crystallites and a crystalline ‘uranyl molybdate’ phase were present. This catalyst exhibited the highest reduction degree by H2 and the highest ESR signal intensity of Mo5+ ions when reduced under very mild conditions. The information obtained with these techniques was used to explain the promotional effect of U on the MoO3/SiO2 base catalyst for the selective oxidation of isobutene.
Surface analysis of semiconductor‐incorporated polymer systems: 2—Pt‐Nafion and Pt‐CdS‐Nafion
Authors: Kakuta N. , Bard A. J. , Campion A. , Fox M. A. , Webber S. E. , White J. M.
Published: May 2005

Pt‐Nafion (chemically reduced and sputtered Pt) and Pt‐CdS‐Nafion membranes were studied by x‐ray photoelectron spectroscopy. The chemically deposited Pt was completely reduced to Pt0 and was more concentrated in the surface region than in the interior. The sputtered Pt (100 Å thick) was distributed within the first several hundred Ångstoms of the Nafion, probably involving Pt migration into it, during the RF sputtering process. Changes of the Pt(4f7/2) linewidth indicate interactions between CdS and Pt. The relatively high activity of the 100 Å sputtered Pt‐CdS‐Nafion membrane for the photoassisted production of H2 in aqueous 0.1 M S2− solution is discussed.
Surface treatment of phlogopite particles for composite applications: XPS and DRIFT studies
Authors: Matienzo L. J. , Shah T. K.
Published: May 2005

The use of XPS and diffuse reflectance fourier transform infrared spectroscopy (DRIFT) to characterize mica surfaces modified with a sulfonylazide alkoxysilane coupling agent in the range of 0.2 to 1.0% (w/w) is discussed. XPS and DRIFT provide a description of chemical composition of the surfaces as well as quantitative analysis of the amount of silane present. Both techniques correlate linearly with the amount of surface treatment. However, DRIFT is more sensitive and faster and does not require an ultra high vaccum system.
A comparison of positive and negative ion static SIMS spectra of polymer surfaces
Authors: Brown A. , Vickerman J. C.
Published: May 2005

Negative ion static SIMS spectra are presented for several polymers whose positive ion spectra have been well characterized previously. The negative cluster ions present in the spectra of poly‐methyl methacrylate, poly‐hydroxy ethylmethacrylate and poly‐ethylene terephthalate provide detailed information on polymer side chain and back‐bone structure complementing and clarifying the information previously only obtainable from positive ion emission. The detection and optimization of structurally informative negative cluster ions is discussed in relation to experimental parameters and the role of surface potential.
Electron channelling induced effects in grain boundary AES measurements
Authors: Bennett B. , Viefhaus H.
Published: May 2005

The influence of incident electron beam angle on the Auger peak height and peak height ratios was studied for clean and surface enriched iron single crystal samples and for grain boundary segregation on polycrystalline samples. The AES measurements were supplemented by observing electron channelling patterns (ECP) for the same samples within a SEM. Auger electron peaks for segregated species Aseg are normalized with respect to the iron substrate Auger peak, AFe, at 651 eV. A considerable change of the Auger peak height ratio Aseg/AFe was observed for surface segregation single crystal planes depending on the incident electron beam angle. The main contribution of the observed changes comes from variations of the iron substrate Auger peak AFe and is attributed to electron channelling effects. The same is true for AES measurements on grain boundaries of polycrystalline samples, if the incident electron beam is nearly parallel to a low index crystallographic pole. Some recommendations are given for performing quantitative AES measurements on grain boundary surfaces.
Surface microstructure investigation of calcined θ‐Al2O3‐supported molybdena catalyst
Authors: Zaki M. I. , Ismail H. M. , Fahim R. B.
Published: May 2005

Samples of θ‐ and α‐Al2O3‐supported molybdena catalyst of various loading levels (0.5–16 wt% MoO3) were prepared by impregnation of the support from a dilute aqueous solution (at pH 6) of ammonium paramolybdate. After drying at 80°C, they were calcined at 550°C for 16 h. The effect of support nature and Mo loading level on surface microstructural characteristics, namely physicochemical identity of the supported Mo‐O species and consequent textural modifications of the calcination products thus yielded, were investigated by means of differential thermal and thermogravimetric analyses, x‐ray diffraction, infrared spectroscopy, scanning electron microscopy and N2 adsorption. The results obtained show that during the thermal treatment of the impregnated samples the adsorbed paramolybdate anions interact preferentially with the thermally most stable surface OH groups (relatively most basic) which reside at the interior and/or entrances of fine pores of the support. They further show that α‐Al2O3 stabilizes the molybdates loaded at up to 12% level in monolayer‐like structures, however α‐Al2O3 does not do likewise giving way to the formation of Al2(MoO4)3 and bulk MoO3 at a loading level as low as 4%.
XPS study on the thermal degradation of poly‐N,N′/4,4′‐diphenylether/pyromellitimide
Authors: Tóth A. , Bertóti I. , Székely T. , Sazanov J. N. , Antonova T. A. , Shchukarev A. V. , Gribanov A. V.
Published: May 2005

Thin foil samples of the title polymer preheated in vacuo up to different temperatures with the highest one reaching 1200 K were analysed by XPS. On heat treatment the surface content of oxygen decreased and that of carbon increased monotonously, while that of nitrogen passed over a local maximum at c. 800 K. Ether‐type oxygens proved to be more heat resistant than carbonyl type ones. From the change of the N 1s peak the probable mechanism of decomposition up to c. 800 K was inferred to be a decarboxylation to give CHN type structures. At higher temperatures decarbonylation of the imide groups appeared to become predominant, resulting in the formation of amide functionalities. The development of a conductive (polyaromatic) structure was deduced from the gradual decrease in the charge shift with the increase of the temperature of pretreatment.
X‐Ray diffraction investigations on ultra‐thin gold films
Authors: Häupl K. , Lang M. , Wissmann P.
Published: May 2005

The structure of epitaxially grown ultra‐thin gold films is investigated by x‐ray diffraction, texture analysis and LEED/Auger techniques. High sensitivity of the x‐ray diffraction analyzer has been achieved by means of a step scanning unit and an impulse height discriminator. The resolving power is then sufficient for the detection of the reflections of films as thin as 1 nm. It is concluded that the particle size broadening is the limiting factor for a further extension of the investigation range towards smaller thicknesses.
Crack imaging in alumina: a scanning acoustic microscope study
Authors: Smith G. C. , Gee M. G.
Published: May 2005

A scanning acoustic microscope (SAM) operating at 750 MHz has been used to image artificially induced cracks in polycrystalline and single crystal specimens of alumina. Although the resolution of the instrument used in this work, at 1.6m̈m, was not as good as that of an optical microscope, significantly more information about the crack characteristics was revealed acoustically. Cracks of finite width act as scattering points for acoustic waves and thus sources of contrast in the SAM image, even when their width is less than the theoretical spatial resolution. In polycrystalline samples it was found that defocussing the SAM both above and below the focal plane, utilising different regions of the V(z) response, enabled contrast due to grain boundaries, cracks, and individual grains to be distinguished. It was also possible to identify different modes of cracking. For the single crystal samples, distinctive contrast was obtained from both horizontal and vertical sub‐surface cracks within one Rayleigh wavelength of the surface. In most materials, features such as these are not readily detectable by other techniques.
On the use of the quartz crystal microbalance for surface analysis in combination with surface sensitive spectroscopies
Authors: Onsgaard J. , Huang W. , Taglauer E.
Published: May 2005

The quartz crystal microbalance (QCM) has a wide range of applications in surface physics and surface chemistry. We present result obtained by combining the high areal density sensitivety of the QCM with surface sensitive spectroscopies like Auger electron spectroscopy (AES) and ion surface scattering (ISS). One type of experiments deals with measurements of sputtering yield variations during ion profiling of metal‐metal interfaces, situated at the surface of the QCM, as a function of varying surface composition. A new method for online measurements of angular distributions of sputtered particles from a solid surface, by utilizing the QCM's as collectors of the ejected particles, is the subject of the other type of experiment.
On the use of markers and tracers to establish the growth mechanism of alumina scales during high temperature oxidation
Authors: Young E. W. A. , Bishop H. E. , De Wit J. H. W.
Published: May 2005

Various ‘marker methods’ have been applied to study the oxidation mechanism of NiAl and Ni‐15Cr‐24Al‐.3Y from 1170 K to 1370 K. Experiments were performed using noble metal markers. The behaviour of both vacuum deposited noble metals as well as implanted noble metals was studied. Also 18O tracers were used. RBS, 18O(p, α)15N resonance spectrometry and SIMS analysis were performed to investigate the alumina scale composition and the position of the marker after oxidation of alloys. The results show that (at 1170 K) NiAl oxidizes mainly by outward diffusion of Al through the oxide scale. It is also shown that noble metal markers may give misleading results. The oxidation mechanism of Ni‐15Cr‐24Al‐.3Y is much more complex. The oxide scale formed on this alloy contains Ni, Cr and Y‐rich oxide regions. These regions contribute to the apparent overall oxidation mechanism of the alloy.
AEM, XPS and ISS characterization of catalyst modifications during propene oxidation over a supported mixed oxide catalyst
Authors: Kremenić G. , Corberán V. Cortés , Tascón J. M. D.
Published: May 2005

The activity of a (MoFeTeCo) O/SiO2 catalyst for propene partial oxidation increases with time on stream, being accompanied by no noticeable change in selectivity to products. The use of a series of characterization techniques (x‐ray diffraction, SEM, analytical electron microscopy, XPS and ISS) allowed us to conclude that the presence of the same phases in the fresh and used catalysts agrees with the constancy of selectivities, while catalytic activity increase is ascribable to a higher degree of dispersion of the active phases. The advantage of the joint use of characterization techniques with different degrees of accessibility to the sample in study are emphasized.
Analysis of plasma enhanced chemical vapour deposition‐grown Borophosphosilicate glass with a combination of Rutherford backscattering and elastic recoil detection
Authors: Oude Elferink J. B. , Dunselman K. , Evers E. J. , Habraken F. H. P. M. , Van Der Weg W. F. , Holsbrink J.
Published: May 2005

It is shown that with a combination of high energy ion beam methods, Rutherford backscattering spectrometry and elastic recoil detection, the elemental composition of borophosphosilicate glass (SiOpPqBrNsHt) can be determined without reference to an external standard. Both thin (< 100 nm) and thick films can be analysed, provided the latter are homogeneous over the layer thickness. Some results pertinent to the B and P uptake during the deposition are briefly discussed.
AES/EDX studies of reactions in phosphate layers during corrosion
Authors: van Ooij W. J.
Published: May 2005

The interface between paint coatings and phosphated automotive steel was investigated using a combined AES/EDX technique. Delamination of the paint during corrosion in salt spray, scab or filiform conditions was found to be controlled by two factors: 1. transformations in the phosphate crystals leading to partial leaching or complete dissolution, 2. wet adhesion retention of the coating in alkaline conditions. The rate of phosphate attack is retarded if the crystals are treated with Cr(III), Cr(VI) or Pb2+ ions prior to coating.
SIMS depth profiling of Al/Nb multilayer structure using Ne, Ar, Kr and Xe ions and neutral species
Authors: Taylor E. , Blanchard B. , Villegier J. C.
Published: May 2005

Depth profiles of Al/Nb multilayer sandwich samples composed of 20 alternating layers (each of 20 Å mean thickness) were obtained by secondary ion mass spectrometry using the Cameca IMS 300. Under bombardment with ions and neutral atoms of Ne, Ar, Kr, and Xe, having energies between 1.5KeV and 5.5 KeV, the effect of the mass and energy of the incident particle on the in‐depth resolution was investigated. The layers were easily visible with atoms of Kr and Xe at 2.0 KeV and 1.5 KeV primary energies while considerable inter‐layer modulations were registered in other cases. An interpretation of the artefacts observed at the beginning and the end of the profiles obtained with 5.5 KeV primary ions was given.
Recent developments in spatially resolved ESCA
Authors: Chaney Robert L.
Published: May 2005

ESCA (electron spectroscopy for chemical analysis) is a general purpose analytical technique for studying the surface properties of a wide variety of materials and material problems. To meet the widest range of experimental conditions, an ESCA instrument should be easily adaptable to the problem under study. The experimental parameters that must be optimized include: spatial resolution; spectral resolution; spectral purity; sample damage; sample presentation; speed of analysis; depth of analysis; sensitivity.

In this paper, we will discuss various concepts used to control these experimental parameters. The discussion will provide an analysis of various methods used to obtain high spatial resolution. Finally, we will describe how to optimize instrument performance for some specific experimental situations.
Chemical and structural characterization of rubber compounds by Auger spectra and imaging
Authors: Lin Sin‐Shong
Published: May 2005

The Auger electron spectroscopic technique combined with the microtome sectioning technique is used to examine the chemical constituents of rubber micro‐structures. This technique together with scanning Auger imaging could be employed to yield gross chemical composition, chemical constituents of micro‐domains, elemental mapping, heterogeneities, as well as the chemical states obtainable from peak lineshape analysis. Furthermore, by chemical contrast, more information concerning the microstructure distributions of rubber matrix could be elucidated.

The preparation of the specimen is crucial for the success of the present characterization of the rubber compounds. Frozen rubber is first sectioned into 10 to 20 μm thick slices; these are either mounted on a conductive adhesive tape or under‐coated with noble metal. The sectioned surfaces are analyzed by scanning Auger microscopic imaging for surface morphology and elemental distribution, and by Auger point analysis for chemical compositions and lineshapes.

The information obtainable includes:(1) overall chemical composition and homogeneity of rubber,(2) dimensions and distributions of rubber components and agglomerates.(3) chemical forms of particle inclusions and agglomerates, and (4) chemical and topological features of surface irregularities. In this paper, the technique for studying rubber compounds is presented, and essential factors affecting the analysis are described.
Voltage contrast XPS—a novel scheme for spatially resolved XPS studies
Authors: Boland John J.
Published: May 2005

A novel scheme is introduced which allows spatially resolved XPS studies to be performed in device applications by taking advantage of the ability to bias the various components of the device. The application of a bias voltage produces a shift in the Fermi level of the biased component and there is a corresponding shift in the binding energy of electrons emitted from this component. In this manner it is possible to discriminate between the XPS signals due to a given element but which originate from different areas of the sample. By analogy with the corresponding biasing scheme employed in SEM studies, this technique has been called Voltage Contrast XPS. To illustrate the capabilities of this technique an application involving a recently proposed integrated thermionic emission device is presented.
Characterization of anodic oxides on 304L stainless steel surfaces
Authors: Gaillard F. , Romand M. , Hocquaux H. , Solomon J. S.
Published: May 2005

The effects of anodization parameters, such as current density, electrolyte concentration, electrolyte temperature, and anodization time on the thickness and composition of the oxides formed on AISI 304L stainless steel anodized in H2SO4K2Cr2O7 were studied by low energy electron induced x‐ray spectroscopy (LEEIXS), glow discharge optical spectroscopy (GDOS), and inert ion sputter profiling in conjunction with Auger electron spectroscopy. The physical and chemical properties of these films were correlated with the results of mechanical tests performed on adhesively bonded structures of the anodized pieces in order to test the feasibility of anodization as a prebond treatment for stainless steel.

Anodization in H2SO4K2Cr2O7 produces a Cr(III) enriched 100 nm thick oxide film. The novel technique of LEEIXS was used to characterize the chemical state of chromium while the hydrogen content of the anodic oxide was determined by GDOS.
X‐ray photoelectron spectroscopic and thermogravimetric studies of rhenium oxides supported on silica
Authors: Cimino A. , Gazzoli D. , Inversi M. , Valigi M.
Published: May 2005

Silica supported rhenium catalysts, containing up to 14% Re (metal) by weight obtained by impregnation with an ammonium perrhenate solution and dried at 110°C, were studied as prepared and then subjected to heat treatments in air, 3 h, in the temperature range 200–750°C.

X‐ray photoelectron spectroscopy (XPS) and thermogravimetry (TG), paralleled by chemical analysis and x‐ray diffraction, were applied to identify the occurrence of an interaction between rhenium species formed by thermal decomposition of NH4ReO4 and silica.

The results indicate that a weak interaction exists between the products of decomposition of NH4ReO4 and silica, influencing the morphology of the rhenium oxide formed and the temperature of volatilization.

The starting material consists of large NH4ReO4 crystals dispersed in the small Cabosil spheres, in agreement with the XPS results (low I(Re)/I(Si) intensity ratio). By heating in air the Re(VII) oxide, produced by the decomposition of the perrhenate, spreads over the silica, as shown by the rise of I(Re)/I(Si) intensity ratio, and its volatilization is slowed down markedly. The volatilization eventually leads to complete loss of Re at about 750°C. The Re(VII) species formed is not in homogeneous situation as indicated by the broadening of the Re 4f peak. A possible scheme for the interaction with the support is suggested.
Angle‐resolved XPS studies of oxides at NbN, NbC, and Nb surfaces
Authors: Darlinski A. , Halbritter J.
Published: May 2005

NbN, NbC and Nb are known to be chemically inert with passivating oxides only solvable in HF acid. Despite Nb2O5 as outermost oxide layer, the oxides of Nb compounds show large differences in thickness and in electronic properties. To quantify the differences, angle‐resolved XPS (ARXPS) measurements have been performed. The simultaneous fitting for different angles and preparations of the Nb, C, N and O XPS lines of the oxides yielded the following stoichiometries and distributions:

Nb2O5 is the outermost oxide layer on NbN, NbC and Nb, followed by:

Nb2N2−xO3+x(x<1) on NbN. Dielectric Nb oxicarbides were not identified for NbC.

Underneath the dielectric metallic oxides NbN1−xOx for NbN, NbC1−xOx for NbC and NbO and NbOx for Nb (x<0.5) occur.

The oxide growth (a)–(c) is not planar; instead, the oxides serrate the metal surface on an nm scale. The serration is strongest for the soft Nb and smallest for the harder compounds NbN and NbC in parallel to the oxidation rate which is slowest for NbC.

The improved oxide quality and better quality of tunnel junctions in comparison with Nb is explained by this first identification of oxinitrides and of reduced serration of NbN (NbC). The first identification of Nb(N, C)1−xOx compounds extending into the metals explains, e.g., regions of depressed superconductivity, leakage current and pinning. The fluxoid pinning is enhanced by dielectric oxides existing for sputtered NbN between the grains and thus explaining the superior superconducting properties of granular NbN.
Multilayer thin film thickness determination with variable exit angle ultrasoft x‐ray fluorescence spectrometry
Authors: Scimeca T. , Andermann G.
Published: May 2005

A theoretical method for obtaining the thickness of thin multilayer films using variable exit angle ultrasoft x‐ray fluorescence spectroscopy is presented. The theoretical approach is based on calculating the ratio of a film's intensity to either an external or internal bulk standard or to another film's intensity within the same sample. The theoretical depth resolution is also discussed using both ratio methods for Fe, Ni multilayer systems. Using this non‐destructive method, some experimental results are also presented for these multilayers.
He(I) photoelectron studies of liquid surfaces—films of malachite green hydroxide and tetramethyl‐p‐phenylenediamine on hydroxypropionitrile solutions
Authors: Ballard R. E. , Jones J. , Read D. , Inchley A.
Published: May 2005

Malachite green hydroxide and tetramethyl‐p‐phenylenediamine from complete films on solutions in hydroxypropionitrile and the He(I) photoelectron spectra of these liquid films are presented. The film of malachite green is shown to be in the covalent form although the ionic form predominates in solution.
Investigation of the sampling volume in secondary ion microanalysis II. Evidence of oxide formation during O implantation in pure elements
Authors: Mai H. , Bauer H.‐D. , KießLing W.
Published: May 2005

Specimen modification in secondary ion microanalysis caused by oxygen primary ion bombardment has been studied for pure elements. The steady‐state primary ion implantation volumes in Al, Si. Fe, Nb, Mo, Ta, and W could be analysed by scanning Auger microanalysis depth profiling, transmission electron microscopy, and electron diffraction imaging. The specimen region modified by the primary ions is found to consist of a metal–oxide phase mixture of various degrees of microcrystallinity, involving amorphous components, too. Whereas chemical state is represented by equilibrium compounds the lattice structure can be of metastable or quasi‐equilibrium configuration.
Segregation of chromium in CoOCr2O3 solid solutions and CoCr2O4 spinel phases studied by SIMS and ESCA
Authors: Sikora I. , Stolze F. , Hirschwald W.
Published: May 2005

Concentration profiles of chromium are investigated by SIMS and XPS in single crystals and polycrystalline solid solutions of chromium in CoO and in the CoCr2O4 spinel. Annealing at high temperatures favours Cr segregation if the oxygen partial pressure is low. The extent of segregation is more pronounced in single crystals. The enrichment depth is comparatively large and the enrichment factor increases with decreasing Cr bulk concentrations.
On the use of water in the measurement of solid surface tension
Authors: McGuire Joseph , Swartzel Kenneth R.
Published: May 2005

Characterization of surfaces which undergo biological fluid contact is often aided by contact angle analysis. A comparison of solid surface tension evaluation methods, particularly addressing a sessile drop technique including and excluding water as a diagnostic liquid, and one in which the surface itself is equilibrated with water is reported for four materials. A particular non‐linear relationship between macromolecular deposition and solid surface tension has been observed in our laboratory and elsewhere. This relationship may not be predicted if surface analysis is performed outside an aqueous environment.
Quantitative depth profiling by glow discharge mass spectrometry
Authors: Hall D. J. , Sanderson N. E.
Published: May 2005

The ability of the VG 9000 glow discharge mass spectrometer to perform highly quantitative materials analysis has led to applications of the instrument in the field of depth profiling. The result has been the emergence of a technique that is capable of performing rapid quantitative depth analysis for a wide range of elements to sub ppm detection limits. Preliminary investigations into depth resolution suggest the capability of resolving nanometre scale structures.

Quantitation is achieved by direct ratioing of ion beams to that of the matrix: elemental sensitivity factors, determined from standards, vary by less than an order of magnitude across the periodic table, and are relatively matrix independent, so that high accuracy results may be attained without the need for closely matching standards and matrix. A high resolution double‐focusing mass spectrometer affords clear separation of atomic peaks from the majority of the inevitable low level molecular species in the mass spectrum, which would otherwise limit the accuracy of trace element determinations.
Application of reflectance studies to layered samples: SiOx on InSb
Authors: Remond G. , Holloway P. H. , Caye R. , Ruzakowski P.
Published: May 2005

Spatially resolved optical micro‐reflectometry in the visible region (from 400 nm to 800 nm) is used to study InSb substrates covered with SiOx (1 < x < 2) films of known thicknesses. Using optical constants (refractive index and extinction coefficient) for uncoated InSb derived from two successive reflectance measurements carried out in air and oil, a model of absorbing films on an absorbing substrate was used to calculate the reflectance. Comparison of measured and calculated reflectances for SiO2 films over InSb demonstrate the validity of the model for an absorbing substrate covered with a homogeneous layer. Optical constants for the SiOx layers are obtained from comparisons between experimental and calculated reflectance curves.
A quantitative surface analytical study of electrochemically‐formed copper oxides by XPS and X‐ray‐induced Auger spectroscopy
Authors: Speckmann H. D. , Haupt S. , Strehblow H.‐H.
Published: May 2005

Electrochemically partially‐oxidized Cu specimens are transferred from the electrolyte (pH 13 and 14) within a closed system without air contact to the UHV and examined with XPS especially by interpreting the x‐ray‐induced Auger signal L3MM. The signal was fitted with standard spectra of clean Cu and Cu2O using an approximation by the Gauss/Lorentz curves. The oxide thickness calculated from the intensity ratio of the Cu2O and Cu signal with an appropriate value for the escape depth of the electrons agrees well with the evaluation of the electrochemical data. Angular dependent measurements permit a reliable examination of Cu2O of less than 0.5 monolayers. The water content of the oxide layer deduced from a quantitative evaluation of the O 1s XPS signal decreases with increasing thickness of Cu2O approaching less than 10% for ca. 10 monolayers. The small amount of hydroxide is located at the outmost layer. The growth of an outer CuO film leads to an increase of the hydroxide content to ca. 30%. These studies show that the Cu L3MM Auger signal may be used to evaluate quantitatively the amount of Cu2O.
Depth analysis of electrodeposited iron–nickel and copper–zinc alloy coatings by glow discharge emission spectroscopy
Authors: Teo W. B. , Hirokawa K.
Published: May 2005

Alloy coatings of FeNi and CuZn electrodeposited on Cu and Fe substrates were analysed with glow discharge spectrometry (GDS) to determine the coating weights of the alloying elements and the concentration depth profile. The coating weight of each element was determined from the integrated intensity which is the area under the intensity‐time curve of the element. A linear relationship is observed between the GDS integrated intensity and the coating weight indicating that GDS is able to quantify the alloy coating. The depth profile obtained was however not the true depth profile because of the effects of sputter broadening (due to differing sputtering rates between the central portion and the edges) and possibly bombardment‐induced segregation (diffusion of zinc towards surface due to the effects of Ar+ bombardment and surface segregation due to heating of the sample) for the CuZn alloy coatings. The use of references of a series of FeNi and CuZn block samples were considered for the determination of the alloy composition. While it is practical for the FeNi system, it is not for the CuZn system because of the effects of surface segregation and bombardment‐induced segregation.
Application of static SIMS to the study of rubber cross‐linking
Authors: van Ooij W. J. , Nahmias M. , Brown A.
Published: May 2005

Static SIMS has been used to analyze the sulfur cross‐links at the surface of compounded polyisoprene rubbers. Linear relationships were found between the normalized intensities of S1− ions and the total cross‐link densities and between the intensities of the S4− clusters and the percentages of the polysulfidic cross‐links.
Platinum contamination of oxide grown by plasma anodization of gallium arsenide
Authors: Lányi Š. , Pavlyák F. , Pinčik E.
Published: May 2005

The contamination of oxide films caused by sputtering of the cathode (Pt) during the anodization of GaAs in an oxygen plasma was investigated. Platinum was found to accumulate near the surface of the oxide, its concentration decreasing rapidly towards the oxide‐semiconductor interface. No correlation of Pt content with deep level spectra from GaAs could be established. The amount of platinum built into the oxide depends sensitively on growth conditions.
Nitridation of polycrystalline titanium as studied by in situ angle‐resolved x‐ray photoelectron spectroscopy
Authors: Ermolieff A. , Bernard P. , Marthon S. , Wittmer P.
Published: May 2005

Nitridation of polycrystalline titanium was investigated in situ at about 550°C by angle‐resolved x‐ray photoelectron spectroscopy (XPS). The nitrogen pressure was varied from 10−4mbar to 1 mbar. The distribution of nitrogen in the titanium and the chemical bonding present were deduced from XPS measurements. Titanium nitridation passes through several stages as a function of the nitrogen exposure. The nitrogen concentration varies linearly with the logarithm of pressure and dose. Using the modified Ritchie‐Hund theory it was shown that the kinetics of titanium nitridation follows a cubic law.
Auger line relative intensities as a tool for the characterization of oxides formed during the oxidation of single crystals of dilute CuMn alloys
Authors: Van Steene G. , Jardinier‐Offergeld M. , Bouillon F.
Published: May 2005

A chemical effect affecting the shape of the copper, manganese and oxygen Auger lines provides a very useful tool for characterization of the oxides formed during high temperature and low pressure oxidation of dilute CuMn alloys.

The state of oxidation of these elements changes the electron distribution in the valence bands, and the relative amplitudes of the Auger transitions involving one or two valence levels have been used as a measure of this effect.
Oxidation of NiCr and NiCrFe alloys at room temperature
Authors: Steffen J. , Hofmann S.
Published: May 2005

The primary stages of the oxidation of NiCr23 and of NiCr21Fe12 and the final oxide layers were studied at room temperature and oxygen pressures between 10−6 Pa and 10−4 Pa using AES and XPS. The composition of the surface during oxygen exposure was monitored by continuous recording of the Auger transitions M23 VV and L3M23V of the metallic components and the KL23L23 transition of oxygen. The low energy M23VV transitions are especially indicative of the present chemical state which is additionally characterized by the 2p photoelectron spectra. After different oxygen exposures, the thickness of the oxide layers was determined by angle resolved AES, XPS results, and by sputter depth profiling which also gives the elemental in depth distribution. It is concluded that the initial preferential oxidation of Cr is followed by a surface enrichment and oxidation of the remaining elements with lower affinity to oxygen, i.e. Ni in NiCr and both Ni and Fe in NiCrFe.
Automated interface recognition in auger sputter depth profiling
Authors: Hill Malcolm D.
Published: May 2005

A range of materials systems has been studied in order to establish whether remote sensing of proximity to an abrupt hetero‐interface can be achieved, in real‐time, during Auger depth profiling. Changes in the absorbed electron current, during both electron and ion beam irradiation of the sample, and variations in the secondary ion yield during sputtering have been measured. In each materials system one or more of these signals has been found to indicate an approaching interface at a significant distance from the onset of the interface in the Auger profile. The application of these findings to the development of methods of acquiring Auger depth profiles rapidly, but without loss of depth resolution at interfaces, is discussed.
Interface analysis using elastic scattering in the transmission electron microscope: Application to the oxidation of silicon
Authors: Ross F. M. , Stobbs W. M.
Published: May 2005

We describe the method of Fresnel fringe contrast analysis and discuss the results obtained by applying the technique to the analysis of the oxides first formed on silicon during wet oxidation. The accuracy of the method is limited at present by the effects which inelastic scattering has on the microscope images. Although these effects are hard to quantify, we show that accurate results can be obtained concerning the sharpness or diffuseness of the Si/SiO2 interface at the atomic level. Combining the results obtained by this method with those found by using high‐resolution electron microscopy for oxides of different thicknesses we are able to conclude that there is a SiOx layer of probably 0.25 nm present during the first stages of oxide growth, but that a further 0.5 nm of crystalline oxide develops well after the start of the oxidation, when the oxide layer is between 2 and 4 nm thick. The implication of these results in relation to the various mechanisms for silicon oxidation which have been proposed are discussed briefly.
Experimental detection limits in scanning auger microscopy at high lateral resolution
Authors: Chazelas J. , Cazaux J. , Gillmann G. , Lynch J. , Szymanski R.
Published: May 2005

Using a scanning Auger microscope at 100 keV primary beam energy it has been possible to analyse a dispersed catalyst particle by particle. The elemental analysis of a 8 nm particle has been obtained for which the number of Pd atoms being detected is estimated to be less than 4000, leading to a detectable mass of 7 × 10−19 g. A silicon sub‐monolayer buried in a GaAs matrix has also been detected, operating at oblique incidence with a 20 nm beam size (minimum detectable concentration < 2 × 10−3). These preliminary experiments illustrate the potential of performing Auger spectroscopy at unconventional primary beam energies (with a field emission gun) when high lateral resolution is required.
Thickness determination of oxide layers on spherically‐shaped metal powders by ESCA
Authors: Nyborg L. , Nylund A. , Olefjord I.
Published: May 2005

The effect of the spherical shape of powder on the determination of oxide thickness in ESCA analysis in investigated. A theoretical model, which takes account of the angular dependence of the X‐ray flux, the photoelectron intensity and the etch rate, is outlined. The model agrees well with experimental depth profiles obtained for Al and Fe powders covered with thin oxide layers (14–20 Å). By using an effective escape depth factor, the thickness of thin oxide layers can be estimated from the oxide and metal intensities. The thickness of oxide layers greater than three times the electron mean free path can be estimated from the etch depth where the metal itensity is 65% of its maximum.
Tinplates and tin/chromium interfaces studied by electron spectroscopies
Authors: Lauristsen F. R. , Onsgaard J. , Vinternes H.
Published: May 2005

Tinplates used for can manufacturing have been analysed by XPS in combination with noble gas ion bombardment. In order to study the influence of the tin coating on the passivation layer, tinplates with different coatings were analysed. In contrast to the chemical measurements a difference was found between a tin coating equal to 1.0 g Sn/m2 and plates with larger coatings. The difference was diminished after a period of six months. With the purpose of clarifying the role of diffusion effects separate investigations of the Sn/Cr interface were conducted. The time effects are explaned by a model where diffusion of chromium due to the presence of tin and due to oxidation of metallic chromium is considered.
Supported rhodium catalysts. Support effects on state and dispersion of the rhodium
Authors: Zaki M. I. , Tesche B. , Kraus L. , Knözinger H.
Published: May 2005

Using SiO2, γ‐Al2O3 as typical examples for acidic, amphoteric and basic oxides, the effect of the support nature on the behaviour of Rh was studied by temperature‐programmed reduction, transmission electron microscopy and IR spectroscopy of adsorbed CO. Reduction is much easier on SiO2 than on Al2O3 and MgO. The highest metal dispersion is stabilized on Al2O3, while particle aggregation to particles with diameters of up to 6 nm occurs on SiO2, during severe reduction and on MgO even under mild reduction conditions. The mobility of RHo atoms and the nucleation rates seem to be larger on MgO than on the other supports. In the presence of CO, the very small particles are disrupted with formation of Rh+(CO)2 complexes at temperature below 300 K; at higher temperatures CO acts as a reducing agent and induces particle growth. It seems that particle disruption is favoured on the supports having the more acidic OH groups. Apart from the support nature, the nature of the precursor complex in solution and the solvent play a decisive role for the reducibility of rhodium.
XPS and SIMS characterization of metal oxide/amorphous silicon—carbon interfaces
Authors: Eicke A. , Bilger G.
Published: May 2005

For different a‐SiC:H/metal oxide (TCO) layers—used for thin film solar cells—migration of metal atoms into the amorphous film, SiOx formation at the interface and reduction of TCO were investigated by SIMS and XPS depth profiling. Zinc oxide seems to be most suitable as a TCO and blocking layer, as the SiOx formation which limits transport of charge carriers is rather low compared to that from SnO2 contacts, and as no Zn is detected in a‐SiC:H in contrast to SnO2 and indium tin oxide ITO with 0.3% Sn and 20 ppm In, the latter acting as counterdopand in p+ a‐SiC:H layers. From correlations between SI yields and elemental concentrations determined by XPS, the quantification of different elements, as well as silicon oxide and metal migration can be deduced from SI intensities. In particular Si+ enhancement is a sensitive indicator for SiOx formation. By these correlations SIMS depth profiling enables fast, quantitative and highly sensitive investigations of numerous samples for optimization of preparation conditions. This is demonstrated in detail for a‐SiC:H/ZnO.
Quantitative Auger analysis of passive films formed on stainless steels
Authors: Lorang G. , Basile F. , Da Cunha Belo M. , Langeron J.‐P.
Published: May 2005

Depth profiling analysis of passive films grown on the surface of Fe17Cr, Fe13.5Cr3.5Si and Fe12Cr5Al alloys (with or without Mo additions) in acidic and basic media has been performed by Auger electron spectroscopy (AES) and ion sputtering. Original depth concentration profiles for oxidized iron and chromium inside the passive film and unoxidized (metallic) components of the alloys were extracted using the sequential‐layer‐sputtering model with the assumption of a step‐like interface between the passivated overlayers and the metallic substrate. A quantitative analysis requires an accurate adjustment of the sputter rate employed as a fitting parameter (related here with numerical values of inelastic mean free paths). In this way, some consistent relationships can be established between the absolute atomic depth distributions of elements constituting the passive films, its thickness and the electrochemical characterization of the alloy resistance with regard to pitting corrosion.
Adhesion of polymers to metals: A review of the results obtained studying a model system
Authors: Boiziau C. , Lecayon G.
Published: May 2005

Following a rapid overview of the various mechanisms involved in the process of polymer adhesion to metals, modelling is attempted in order to describe, at molecular scale, the metal—polymer interface in its technological reality. In particular, the concept of an active site is explained and the role of these sites in bonding mechanisms is illustrated.

The model is then verified in laboratory using experimental and theoretical techniques appropriate for the problem posed. Electrochemistry in organic environment is used to impart to the surfaces a homogeneous acid or basic character (i.e. electron acceptor or donor) and to set up an intense anisotropic electrical field allowing nonrandom simulation of the fields induced by the roughness of the potential of the surface of an industrial object. It is thus demonstrated that the establishment of a strong metal—polymer bond results from so‐called Lewis acid—base reactions activated by the interfacial electrical field.

Finally, the ageing study of the metal—polymer system thus obtained shows that the interface is stable relative to atmospheric oxygen and that vacuum pyrolysis converts the polymer into a carbon fibre strongly bonded to the metal.
Study of the Al/PET interface in relation with adhesion
Authors: De Puydt Y. , Bertrand P. , Lutgen P.
Published: May 2005

Thermally evaporated aluminium thin layers have been deposited on two different industrial Polyester (PET) films. The Peel test shows that adhesion between Al films and PET depends on the heat setting conditions of the PET foils.

In order to explain the observed differences in adhesion, ISS analyses were performed on the two surfaces obtained after peeling aluminium from the PET substrates. The Al/PET laminates were also studies by SIMS, RBS and TEM.

ISS results show that the failure mechanisms differ for the two samples investigated. From the SIMS depth profiles, a lower sputtering rate is found for the sample presenting a lower adhesion, and RBS spectra show that the Al/PET interface is steeper for this sample. Also, marked differences in the Al grain sizes are observed by TEM: larger grains without preferred orientation are found on Al layers of poor adhesion.

These results are discussed in view of elucidating the influence of the substrate properties on the metal/polymer adhesion.