bluuebunny/crossref_metadata_2025 huggingface dataset:
AES investigations of chemical composition of some alkali compounds
Authors: Dolizy P. , Grolière F.
Published: December 2004

Auger electron spectroscopy is used as a quantitative and qualitative tool to investigate solid surfaces. Conventional quantitative analyses are based on the comparison of the Auger signal from the sample to that from pure standard. A detailed analysis of peak shape of Auger signal shows that the upper part of the derived Auger line (lower energy side) is strongly related to the chemical bonding whereas the lower part (high energy side) is nearly insensitive to the chemical effects.

A calibration method for quantitative Auger spectroscopy based on the amplitude variation of the LVV Auger transitions of one element as a function of its chemical bonding within the compound is described. This method takes into account sample ‘matrix’ effects as well as all kinds of instrumental effects on the measured Auger signal.

It has been also shown that AES can be used to make successful chemical analyses on alkali antimonides. A direct relation between electronic charge transfer between atoms and Auger peak shape has been observed, it is used to relate photoelectric quantum yield of SbKx compound to the ionicity of the Sb–K bond.
Household applications of surface analysis— vinyl floor finishes
Authors: Webb R. L. , Brinen J. S.
Published: December 2004

Oil contact angles on six commercially available floor finish films were found to vary widely. ESCA measurements of the surface chemical composition of these films revealed unexpectedly large variations. A linear correlation between surface chemical composition and the work of adhesion to the surface was found.
XPS and AES quantitative surface analysis: Comparison on oxide powder systems
Authors: Garbassi Fabio
Published: December 2004

XPS and AES quantitative surface analyses on several oxide systems, containing two or three metal elements, are compared. Both single‐phase and multi‐phase systems have been investigated, representative of a variety of situations regarding surface v. bulk composition relationships. Metal‐to‐metal ratios obtained via the two techniques have been compared. A very intimate intermixing of cations, as it happens in single‐phase systems (i.e. solid solutions), appears a necessary but not sufficient condition for obtaining good correlation between the results of the two spectroscopies. Slopes of the straight lines correlationg XPS and AES data are generally far from the expected value of 1, suggesting the existence of strong matrix effects for at least one of the two techniques.
ESCA study of the adhesion of Ag, Cu and Ni to polysiloxane resins used in the semiconductor industry
Authors: Torrisi A. , Marletta G. , Puglisi O. , Pignataro S.
Published: December 2004

Commercial polysiloxane resins used in the semiconductor industry were moulded on Ag, Ni and Cu real surfaces. The samples were broken by using a pull test machine and the joint strength measured. The ‘resin’ and ‘metal’ faces obtained in the rupture process were analysed by ESCA. The chemical composition of the two faces was very different. The one from the resin side resembled that of the bulk. That from the metal side was rich in additives from the commercial resin. Some differences were found between the three metals, whilst the spiral flow of the resin in the range examined influenced the results in only a very limited way. The weak boundary layer in which the above additives accumulate seems responsible for the low adhesion level found. The Pb/Si concentration ratio at the fracture locus is correlated with the adhesive joint strength. The multifactorial nature of the adhesion in practical samples is discussed. It is suggested that the influence of the heavy elements present in the additive has to be explored in connection not only with the adhesion problem but also with the electrical reliability of the device.
Rutherford backscattering spectrometry as an experimental method to study the oxidation mechanism of NiAl3 alloy
Authors: Young E. W. A. , De Wit J. H. W.
Published: December 2004

The oxidation mechanism of NiAl3 alloy is investigated by means of Rutherford Backscattering Spectrometry (RBS), using 2.0 MeV He+ ions. In addition SEM and thermogravimetry experiments were performed. The oxidation characteristics of Ni–Al alloys are of interest because of their application as coating materials on high temperature alloys. It is found that during thermal oxidation at 973 K, an Al2O3 scale is formed on the alloy. The scale grows at a sub‐parabolic rate and does not spall‐off. These characteristics make NiAl3 a promising coating material.
Characterization of a high depth‐resolution tantalum pentoxide sputter profiling reference material
Authors: Hunt C. P. , Seah M. P.
Published: December 2004

A major use of surface analysis instruments concerns composition depth profiling. In many instances poor depth resolution is obtained, one cause of which is poor ion beam alignment and uniformity. To enable instrument users to optimise instrument settings and know (1) the instrument contribution to depth resolution and (2) the ion etch rate, tantalum pentoxide reference materials have been developed with thicknesses of 30 nm and 100 nm and interface widths, measured by AES, of 1.5 and 1.7 nm respectively. The effects of argon ion beam energy, electron beam current density, sputtering geometry and gas purity effects on etch rate and interface width are measured and interpreted in terms of basic parameters, showing that the material is a well‐behaved model system that is robust and easily used. The precise shape of the interface and preferential sputtering effects are also analysed.
Advances in charge neutralization for XPS measurements of nonconducting materials
Authors: Barth G. , Linder R. , Bryson C.
Published: December 2004

The build‐up of a positive charge during the XPS measurement of nonconducting materials can severely affect the spectral resolution leading to line broadening and time‐dependent energy shifts. The use of a low kinetic energy electron flood gun in conjunction with a metal screen placed in close proximity to the sample surface permits the establishment of a uniform surface potential. The advantages of this approach are demonstrated with spectral data taken from a variety of organic materials. Spectral line widths of 0.9–1.3 eV are routinely obtainable for the C(1s) core level photoelctron signals. Further, the reproducibility obtained on line positions (±0.1 eV) allows the use of a calibration procedure to study the relative line positions between different samples. This combined with better resolution allows a more complete assignment of spectral features including some nearest neighbor effects. A shift between aromatic and aliphatic C(1s) lines is observed.
Characterization of polyamic acid/polyimide films in the nanometric thickness range from spin‐deposited polyamic acid
Authors: Russat Jean
Published: December 2004

A dilute polyamic acid solution was spin‐deposited onto gold substrates and XPS analyses were performed after deposition. Evidence of the presence of organic films on the top surface of the substrates was found. A chemical characterization allowed us to identify these organic films as being polyamic acid after a 125°C curing and polyimide after a 240°C curing. From angle‐dependent data we have shown that the gold substrates were coated quasi‐uniformly by ultra‐thin films. This conclusion was confirmed by an Auger analysis. The computed thickness were found in a range of 1.3 to 2.9 nm depending on the sample preparation conditions. Adsorption was supposed to occur just after the deposition. Some possible mechanisms of the interfacial interaction between the polyamic acid and the surface were proposed. A thermally‐activated chain cleavage was supposed to occur at the interface or near the interface.
Depth analysis of metal coatings by glow discharge spectroscopy with emphasis on the interface problem
Authors: Teo W. B. , Hirokawa K.
Published: December 2004

Grimm glow discharge spectrometry was used to analyze metal coatings on various metal substrates to determine the sputter broadening characteristics of the glow discharge lamp, especially at the interface. The sputter broadening characteristics are important when the depth profile is to be found. The samples of Cu/Ni, Ni/Cu, Sn/Ni, Ni/Sn, Fe/Ni, Ni/Fe metal coatings investigated, indicate that the poor depth resolution of glow discharge spectrometry is due to uneven profiling since the central portion of the sputtered surface is sputtered away faster than the edges. This depth resolution problem is fundamentally different from that of depth profiling in AES or SIMS. Besides being dependent on the usual sputtering parameters the depth profile is also dependent on the glow discharge characteristics of the coating metal and substrate metal combination. From the plots of plasma composition vs. fraction of metal coating sputtered, plasma composition vs. depth sputtered and fraction of metal coating sputtered vs. depth sputtered, the development of the crater profile can be followed and the cause of the depth resolution problem evaluated.
The precise determination of concentration distributions using depth‐sectioning methods
Authors: Katardjiev I. V. , Nobes M. J. , Carter G.
Published: December 2004

Consideration of the continuity equation relating atomic fluxes entering and leaving a layer from the instantaneous surface to a fixed depth beyond the extent of any atomic relocation shows that measurements of total atomic exit flux, of a given species, the rate of change with time of the species concentration over the fixed depth, and sputtering speed, can yield initial depth distributions of the atomic species.
Surface reactions of copper films in O2/CF4/N2 plasmas
Authors: Coolbaugh D. D. , Matienzo L. J. , Egitto F. D. , Knoll A. R.
Published: December 2004

Copper surfaces treated with O2/CF4 and O2/CF4/N2 plasmas have been characterized using x‐ray photoelectron and Auger electron spectroscopy. Deeper oxidation and fluorination result for oxygen‐rich mixtures than for CF4‐rich gas feeds. Film thicknesses increase with time of exposure. Copper oxidation is always deeper than fluorination for O2/CF4 mixtures. It appears that penetration of fluorine is more facile through the copper oxide matrix than through the metallic copper film. With addition of 5% N2, concentration of fluorine is enhanced relative to oxygen. These observations are discussed with respect to gas phase and surface reactions involving oxygen, fluorine and nitrogen.
The effects of excimer laser annealing and yttria on corrosion of an FeCrNi alloy at 700°C
Authors: Baer D. R. , Wright I. G. , Jervis T. R.
Published: December 2004

Several surface and near‐surface analysis methods have been used to examine the effects of excimer (KrF, 248 nm) laser annealing and the addition of 2 wt.% Y2O3 on the early stages of corrosion of an Fe‐25Cr‐20Ni alloy at 700°C. Two specific questions were addressed experimentally: (1) Can excimer laser treatment improve the corrosion properties of the FeCrNi alloy in a mixed gas environment (containing oxygen and sulfur)?; (2) Does the Y2O3‐induced improvement of the corrosion behavior of the alloy result from prevention of S segregation to the surface or scale‐metal interface? Results show that laser annealing increased the Cr surface concentration of the treated alloy, but did not enhance the formation of a Cr‐rich oxide. However, the treated alloy was less susceptible to scale breakdown and sulfide formation. Surface segregation of S was not prevented by the Y2O3 addition. Differences between doped and undoped alloys may be attributable primarily to changes in microstructure.
Decomposition of 2p3/2 bands in XPS spectra of Fe, Co and Ni compounds
Authors: Stoch J. , Capecki A.
Published: December 2004

A procedure is described for handling the XPS spectra of Fe, Co and Ni compounds. For background removal, a modified Shirley algorithm is used. The background line shape and position are determined from the spectrum by a procedure of successive iterations, which are repeated until the ratio of peak heights in the 2p doublet reaches a value approximately equal to the ratio of the photoelectron cross‐sections. An experimental value of 2.1 for the ratio is suggested.
Program for XPS spectrum conversion to VGS‐5000 format
Authors: Abel P. B.
Published: December 2004

A FORTRAN program has been written for use on an IBM‐PC/XT/AT or compatible microcomputer (PC) that converts a column of ASCII‐format numbers into a binary‐format file suitable for interactive analysis on a Digital Equipment Corporation (DEC) computer running the VGS‐5000 Enhanced Data Processing (EDP) software package. The incompatible floating‐point number representations of the two computers were compared, and a subroutine was created to store correctly on the PC floating‐point numbers in a format that can be read directly by DEC computers. The data file header required by the EDP programs for an x‐ray photoelectron spectrum is also written to the file.
Quantitative analysis of SIMS spectra of mixtures of powders of FeSO4 and ZnSO4
Authors: Michaud Daniel , Baril Marcel , Adnot Alain
Published: December 2004

Binary mixtures of powders of iron and zinc sulphate have been analysed with SIMS. The proportions of iron, used as representative species, were calculated with an empirical method based on the sensitivity factor. An accuracy of 7% relative has been obtained on these calculated proportions. Results obtained with two different SIMS instruments are compared, as well as results obtained by an XPS analysis.
X‐ray photoelectron spectroscopic studies of thin film oxides of cobalt and molybdenum
Authors: McIntyre N. S. , Johnston D. D. , Coatsworth L. L. , Davidson R. D. , Brown J. R.
Published: December 2004

Surface oxidation reactions of cobalt, molybdenum and mixed cobalt–molybdenum metals have been investigated using x‐ray photoelectron spectroscopy (XPS). The oxide stoichiometries have been determined from XPS intensity measurements. Such quantification has been important in identifying oxide compositions with characteristic XPS spectra. A number of discrete binary molybdenum oxides have been characterized after reactions at 200°C and pressures ranging from 1 atm to 10−6 Pa. At the lowest pressure, the Mo 3d spectra and O/Mo ratios suggest the formation of a molybdenum–oxygen structure with a stoichiometry near unity. By contrast, at higher pressures, oxides that are predominantly MoO2 and MoO3 appear, but other intermediate oxide structures are also identified. Well‐defined binary oxides of cobalt can be prepared from cobalt metal after heating in oxygen at different pressures. New binary oxides of cobalt and molybdenum have been generated by the reaction on MoO3 or Co3O4 substrates. Oxidation of a thin film of molybdenum on a Co3O4 substrate has been shown to produce a nearly stoichiometric surface layer of CoMoO4. The procedure could be useful for the production of other ternary oxides of possible interest for use as XPS reference materials.
AES and RBS analyses of tokamak collector probes—experimental considerations
Authors: Paynter R. W. , Ross G. G.
Published: December 2004

Analyses by RBS and AES of beryllium collector samples exposed to discharges in the Tokamak de Varennes have been made. Good agreement for the total amounts and types of material deposited on collectors oriented in each of three ways was observed. However, analysis of the AES sputter‐depth profile indicated a peaking of the metal near the outer surface of the collectors. This can be explained by a simple model involving sputtering and redeposition during the tokamak discharge. Implications of this model are that the average amount of material deposited on the collectors may not be related directly to impurity concentrations in the plasma. Experimental analysis of material deposited on the collectors must be made with sufficient depth resolution to obtain information about sputter–redeposition activities during plasma discharges.
AES: Energy calibration of electron spectrometers. I—an absolute, traceable energy calibration and the provision of atomic reference line energies
Authors: Seah M. P. , Smith G. C. , Anthony M. T.
Published: December 2004

Experiments have been made to provide calibrated kinetic energy values for AES peaks in order to calibrate Auger electron spectrometers of various resolving powers. The kinetic energies are measured using a VG Scientific ESCALAB II, which has power supplies appropriate for AES measurements in both the constant ΔE and constant ΔE/E modes. The absolute calibration of the energy scale is obtained by the development of a new measurement chain, which, in turn, is calibrated in terms of the post‐1990 representation of electron‐volts using XPS peaks with a traceable kinetic energy accuracy of 0.02 eV. The effects of instrumental and operating parameters, including the spectrometer dispersion and stray magnetic fields, are all assessed and contribute errors for three peaks not exceeding 0.06 eV and for two peaks not exceeding 0.03 eV. Calibrated positions in the direct spectrum are given for the Cu M2,3VV, Au N6,7VV, Ag M4NN, Cu L3VV and Au M5N6,7N6,7 transitions at 0.2 eV resolution, referred to both the Standard Vacuum Level and the Fermi level. For the differential spectrum, the positions of the negative excursions are derived numerically by computer from these data and are established with the same accuracy. Data are tabulated for the above peaks in both the direct and differentiated modes for the popular resolutions of 0.15%, 0.3% and 0.6% produced by Gaussian broadening of the high‐resolution spectra. Differentiations are effected by both sinusoidal modulation and Savitzky–Golay functions of 2 eV and 5 eV peak‐to‐peak.
Surface composition and chemical bonding of thermally reduced yttria as studied by XPS and SEXAFS: Influence of Zr doping
Authors: Thromat N. , Gautier M. , Jollet F. , Duraud J. P. , Le Gressus C.
Published: December 2004

Surfaces of thermally reduced yttria, either pure (5 N) or doped with Zr, are studied by means of x‐ray absorption spectroscopy (surface‐extended x‐ray absorption fine structures), x‐ray‐induced Auger electron spectroscopy and x‐ray photoelectron spectroscopy. No Zr surface segregation is observed for the solid solutions considered, (100 − x) YO1.5 + xZrO2 (with x = 5.3 or 13), whatever the thermal treatment experienced.

In pure and Zr‐doped yttria, the concentration of oxygen vacancies is estimated at the surface as a function of reduction time: while, in the early stages, oxygen deficiency appears to be spatially homogeneous, after a certain time the first atomic layers are much more oxygen‐depleted than the bulk. The introduction of oxygen vacancies in the lattice leads to a modification of the YO bond, which corresponds to a decrease of the local atomic charge on the remaining oxygen atoms, as observed from the Auger O KLL lineshape. This decrease in the ionic character of the bond causes an increase in the total polarizability and of the surface optical dielectric constant, as deduced from O and Y Auger parameter measurements. These variations are weaker in the doped samples, which could be due to a smaller static disorder compared to that of pure samples.
Monte carlo calculations of the X‐ray induced enhancement signal in electron probe microanalysis (EPMA) and Auger electron spectroscopy (AES) of stratified materials
Authors: Nassiopoulos A. G. , Valamontes E.
Published: December 2004

When thin overlayers on a bulk material have to be analysed by EPMA (electron probe microanalysis) or AES (Auger electron spectroscopy), the signal obtained is enhanced by three factors: (i) back‐scattering, (ii) characteristic x‐rays induced in the bulk by the primary beam and (iii) continuous x‐rays (bremsstrahlung) created also in the bulk. The Monte Carlo techniques are applied in order to evaluate the above three enhancement factors when the primary energy is varied in the range 5–50 keV. It is shown that at high primary energies the second and third factors are no longer negligible and become significant in some cases. The approximation to ignore the third factor in EPMA and both the second and third factors in AES is not always valid and introduces an appreciable error. Results are shown for the case of thin films (Al, Au, Cu) on a bulk material (Au, Cu, Si, Ni, Pt).
Sputter depth profile analysis of marker layers
Authors: Peinador J. A. , Abril I. , Jiménez‐Rodríguez J. J. , Gras‐Marti A.
Published: December 2004

We study theoretically the distortion of marker layers embedded in homogeneous media due to energetic ion bombardment. For realistic relocation cross‐sections, we have solved the balance equation, first proposed by Sigmund and co‐workers, for the evolution of irradiated polyatomic targets. The collisional mixing operator accounts for recoil mixing, isotropic cascade mixing and surface barrier effects.

Following the evolution with ion fluence of the marker concentration profiles, we can obtain the tracer yield, which is related directly to the as‐recorded intensity in a SIMS experiment. The influence of the surface barrier on signal broadening also will be discussed.
Evaluation of correction accuracy of several schemes for AES matrix effect corrections
Authors: Tanuma S. , Sekine T. , Yoshihara K. , Shimizu R. , Homma T. , Tokutaka H. , Goto K. , Uemura M. , Fujita D. , Kurokawa A. , Ichimura S. , Oshima C. , Kurahashi M. , Kudo M. , Hashiguchi Y. , Suzuki T. , Ohmura T. , Soeda F. , Tanaka K. , Tanaka A. , Shiokawa Y. , Hayashi T.
Published: December 2004

A matrix effect correction is required to improve the accuracy of quantitative AES analysis. The correction includes terms involving the atomic density (n), electron back‐scattering factor (R) and electron escape depth (L). Many schemes have been proposed by various people for corrections of the R and L terms. However, up to now, there have been no systematic investigations of the correction accuracy of the proposed schemes. We have evaluated the correction accuracy, based on measured intensity data for AuCu alloys of different compositions. Comparison was made between the observed intensity ratio K (=Iunk/Istd) and the calculated intensity, ratio K′ (= C(nunk/nstd)(Runk/Rstd)(Lunk/Lstd)), where C and I represent the concentration and intensity, respectively. The superscripts ‘unk’ and ‘std’ denote that the parameters are for unknown and standard specimens, here the pure elements. If the correction works well, the error Er (= K′  K)/(K) will become smaller. Evaluations were carried out on three schemes for the R correction and on seven schemes for the L correction using the Au 239 eV, Au 2024 eV and Cu 920 eV transitions. The root mean square (RMS) of the calculated errors showed several per cent for the best case and 20–30% for the worst case. The RMS error varied a few per cent between schemes for the R correction but it varied ∼30% for the L correction.
Sputter reduction of oxides by ion bombardment during Auger depth profile analysis
Authors: Mitchell D. F. , Sproule G. I. , Graham M. J.
Published: December 2004

Quantification of the magnitude of preferential sputtering of oxygen from metallic oxides has been examined for a large number of 30 nm thick amorphous oxides deposited onto polished silicon substrates. The method of analysis was derivative‐mode Auger analysis carried out in a cleaner vacuum system and with cleaner initial surfaces than has been the case usually for data found in the literature. Ion sputtering was primarily with 3 keV xenon ions but the effect of ion energy (1, 3 and 4.5 keV), ion mass (argon or xenon) and sputter rate was also examined. The magnitude of preferential sputtering at 20°C was generally much less than has been reported previously and was not a function of ion energy, mass or sputter rate over the range studied. The results separate into two groups: oxides that reduce appreciably and those that do not. The results agree well with the predictions from the theoretical model of Kelly.1 It must be concluded from the work that most of the data reported in literature are primarily the result of unrecognized and therefore unreported variables. Likely candidates are contaminants within the ion beam and background environment that contribute chemical effects to the sputter process, ion beam and electron beam heating of poorly conducting samples, or redeposition of sputtered material into the analysis area.
The characterization of doped and undoped states of conducting polypyrrole, poly‐3‐methylthiophene and poly(3‐thiopheneacetic acid) thin films on a platinum surface by specular‐reflectance Fourier transform infrared spectroscopy
Authors: Wang Jin Hai
Published: December 2004

An improved specular‐reflectance Fourier transform infrared spectroscopy (SRFTIRS) is applied in the characterization of several kinds of conducting polymer, which were synthesized electrochemically and coated on platinum electrodes. This technique allows the use of the same electrode as that used in electrochemical experiments as the optical reflectance substrate and requires no further sampling. Satisfactory spectra were obtained for a variety of film thicknesses. Both the conducting and insulating states of the polymer and the anion and cation dopants can be identified clearly. The technique is fast, very versatile and convenient. Furthermore, the results obtained indicate its potential application in the analysis and characterization of other conducting polymer films and/or other coatings on metal substrates.
XPS study of mixed cerium–terbium orthophosphate catalysts
Authors: Pemba‐Mabiala J. M. , Lenzi M. , Lenzi J. , Lebugle A.
Published: December 2004

Monazite structure‐type solid solutions of cerium and terbium orthophosphates Ce1−xTbxPO4, with 0 < x < 1, were prepared by coprecipitation followed by calcination at 800°C for 2 h. They were used as catalysts for the oxidative dehydrogenation of ethylbenzene.

The compounds Ce0.9Tb0.1PO4 and Ce0.7Tb0.3PO4, which give the maximum yield of styrene, were studied by XPS before and after catalysis. The binding energies were determined with carbon contamination as a reference (level 1s). Quantitative analysis was performed by using the limit compounds CePO4 and TbPO4 as standards. The surface composition before catalysis is slightly different from the bulk composition, whereas no significant variation of binding energies is observed. After catalysis, an important broadening of the peaks and a decrease of the (Ce + Tb)/P ratio appears. The decomposition of the P 2p and O 1s peaks allows us to show the formation of pyrophosphate at the catalyst surface. The formation of this phase during the catalytic reaction is connected to the mechanism of the surface reaction.
XPS analytical characterization of amorphous alloys: Fe70Cr10P13C7
Authors: De Filippo D. , Rossi A. , Elsener B. , Virtanen S.
Published: December 2004

A qualitative and semiquantitative XPS analysis of the surface films formed on the amorphous Fe70Cr10P13C7alloy in the as‐received state after rapid quenching, after mechanical abrasion and after anodic passivation at +500 mV SCE in 1 N HCl was performed. A method for simulataneous evaluation of the thickness of the oxide layer and its composition is proposed.

The results clearly show that oxidized phosphorus is incorporated in the outer layer of the passive film formed after anodic polarization at +500 mV SCE, in agreement with the model of the bipolar cation‐selective passive film proposed to explain the outstanding corrosion resistance of the alloy tested.
Depth profiling resonance ionization mass spectrometry of Be‐doped, layered III–V compound semiconductors
Authors: Downey S. W. , Emerson A. B. , Kopf R. F. , Kuo J. M.
Published: December 2004

The accumulation of Be at the interfaces of p‐type (NBe = 2 × 1019 cm−3) GaAs/AlAs and InGaAs/InAlAs structures grown by molecular beam epitaxy (MBE) is detected by depth profiling resonance ionization mass spectrometry (DPRIMS). These results help to interpret secondary ionization mass spectrometry (SIMS) matrix effects at interfaces. The magnitude of the effect depends upon the layer sequence. DPRIMS of heterojunction bipolar transistor (HBT) structures, made of GaAs and AlGaAs layers, show transient SIMS matrix effects from layers spaced 10.0 nm apart. Mass interferences in the Be profile of the HBT structure is precluded with DPRIMS. Therefore, this method allows more accurate interpretation of dopant profiles in these types of structures.
Surface segregation of substrate element on metal films in film/substrate combinations with Nb, Ti and Cu
Authors: Yoshitake M. , Yoshihara K.
Published: December 2004

The surface segregation of the substrate element on metal film by diffusion through the film was studied. Six film/substrate couples—Nb/Ti, Ti/Nb, Cu/Nb, Nb/Cu, Cu/Ti and Ti/Cu—deposited by rf magnetron sputtering were applied to investigate segregation behaviour, as well as Nb/Ti and Ti/Nb deposited by electron beam. The segregation behaviour of the substrate element by diffusion through the films was monitored at the film surface by AES. For Nb/Ti, Cu/Nb, Cu/Ti and Ti/Cu, the substrate element segregated on the film surface by diffusing through the film with a diffusion coefficient much larger than that corresponding to volume diffusion in the bulk. The segregation of Cu on Ti film was affected by an exposure of 2.6 × 10−6 Pa oxygen during heating. The activation energy for this diffusion was ∼60% of that in the bulk and the diffusion path seems to be the grain boundaries. The occurrence of this segregation via grain boundary diffusion did not depend on the film preparation process. From these results, the driving force of the segregation via grain boundary diffusion may be the decrease process. From these results, the driving force of the segregation via grain boundary diffusion may be the decrease of the surface free energy of film by the segregation of substrate element on grain boundaries and surfaces of films.
Analysis of polymer surfaces by SIMS: Part 15. Oxygen‐functionalized aliphatic homopolymers
Authors: Chilkoti Ashutosh , Ratner Buddy D. , Briggs David
Published: December 2004

The positive and negative ion spectra from simple oxygen‐containing aliphatic homopolymers (i.e. ethers, ketones, carboxylates and backbone esters) are reported. Interpretation of the static SIMS fragmentation patterns of these polymers is shown to be related to the structure of the polymer, in particular its heterofunctionality. A systematic investigation of the atomic secondary anions that are ubiquitous to all organic polymers reveals that their relative yields are not devoid of chemical information, but appear to be related to polymer structure.
Remarks on the surface characterization of carbon fibres
Authors: Desimoni E. , Casella G. I. , Cataldi T. R. I. , Salvi A. M. , Rotunno T. , Di Croce E.
Published: December 2004

The characterization of carbon fibres by x‐ray photoelectron spectroscopy depends on several experimental and theoretical aspects that noticeably improve the accuracy of the analysis when properly taken into account. These aspects are briefly discussed in the light of the most representative literature available. Attention is focused on points that need a deeper understanding and suggestions are given about possible analysis strategies.
Structural properties of BN thin films obtained by plasma‐enhanced chemical vapour deposition
Authors: Montero I. , Galán L. , Osòrio S. P. , Martínez‐Duart J. M. , Perrière J.
Published: December 2004

In this work BN films have been deposited by the plasma‐enhanced chemical vapour deposition (PECVD) technique on p‐type (100) silicon substrates, using borazine and nitrogen as precursors. X‐ray photoelectron spectroscopy, infrared spectroscopy, x‐ray diffraction, nuclear reaction analysis and Rutherford backscattering spectroscopy were used to analyse the films. The results of quantitative XPS analysis indicate the formation of a thin surface layer (∼3 nm) of boron oxynitride, BNO0.3, over a bulk of nearly stoichiometric boron nitride, BN1.1. The presence of the hexagonal phase mixed with amorphous boron nitride was identified. Infrared and Rutherford backscattering spectroscopies combined with a liquid etching technique were used to determine the composition and structure across the film thickness. From these measurements we infer that the composition across the film is nearly constant but with a gradual transition from an amorphous structure close to the Si/BN1.1 interface to an hexagonal structure towards the outer layers. Thermal treatments of the boron nitride films up to a temperature of ∼1000°C in a nitrogen atmosphere resulted in a small decrease of both the B/N atomic concentration ratio and the refractive index of the film. The insulating characteristics of the boron nitride for application as an intermetal dielectric were also treated. The electrical conduction results can be interpreted in terms of a Schottky mechanism, which allows us to calculate the high‐frequency dielectric constant, εr = 3.2.
X‐ray photoemission spectroscopy and scanning Auger microscopy studies of a Roman lead pipe ‘fistula’
Authors: Paparazzo E. , Moretto L. , D'Amato Clotide , Palmieri A.
Published: December 2004

We report scanning Auger microscopy (SAM) and x‐ray photoemission spectroscopy (XPS) analysis of a Roman lead pipe ‘flstula’, the main emphasis being placed on the comparison between the surface and interface chemical composition of the joint and of the rest of the pipe. We find that the ‘tertiarium,’ a Pb–Sn alloy that the Romans used for soldering the joint, has a beneficial effect in limiting the formation of white lead, 2PbCO3·Pb(OH)2·Comparison measurements performed in the alloy and the pure separate metals show that tin markedly limits the ambient surface oxdation of lead. Conversely, tin is much more oxidized in the alloy than when analysed alone. Auger point spectra indicate that carbon is the main surface contaminant of the patina of the fistula, and Auger imaging is used to pinpoint, with a spatial resolution of ∼0.5 ∼m, the distribution of this element at the interface of a lead/tertiarium solder, performed according to the procedures described by Plinius. The diagnostic capability of Auger transitions of lead and tin for distinguishing between different phases is discussed on the basis of their chemical shifts and surface sensitivities.
Auger/LEED linear heating study of Sn and S bulk‐to‐surface diffusion in a Cu(111)(Sn, S) single crystal
Authors: Viljoen E. C. , Du Plessis J.
Published: December 2004

The novel technique of linearly heating a sample to obtain both the pre‐exponential factor D0 and the activation energy E from a single run is applied to the Cu(111)(Sn, S) system. Using Auger electron spectroscopy the surface enrichment is measured as a function of time (temperature) and fitted with an integral expression containing the fit parameters D0 and E. The fit values at all heating rates agree excellently with published, our own experimental and conventional t1/2 values after temperature corrections.
XPS analysis of metal grain boundary surfaces
Authors: Hallam K. R. , Wild R. K.
Published: December 2004

X‐ray photoelectron spectroscopy (XPS) can provide a quantitative analysis of the surface and determine the chemical state of elements present. However, until recently the spatial resolution has not been adequate to analyse small particles. As a result, Auger electron spectroscopy has been used to obtain elemental information where good spatial resolution is required. Analysis of grain boundary surfaces has therefore been restricted to this technique, with the result that no chemical‐state information has been obtained relating to the elements present on the grain boundary. This paper describes results in which grain boundary surfaces exposed in an imaging XPS instrument have been analysed using XPS. In particular, tin and phosphorus are shown to segregate to the grain boundary surface in the elemental state.
Monitoring the surface coverage of W/TiO2 catalysts by ion scattering spectroscopy
Authors: Fiedor Joseph N. , Houalla Marwan , Proctor Andrew , Hercules David M.
Published: December 2004

A series of W/TiO2 catalysts was prepared by incipient wetness impregnation with W loadings varying from 1.64 to 28.4 wt.% WO3. The coverage of the TiO2 surface by W species was monitored by ion scattering spectroscopy (ISS). The results indicated that the W coverage increased from 21.6% for the 1.64 wt.% WO3/TiO2 catalyst to ∼85% for catalysts with W loadings ≥10.3 wt.% WO3. These values agreed with those predicted from monolayer‐like dispersion. The relatively constant coverage for W loadings > 10.3 wt.% WO3 was taken as an indication of multilayer or WO3 formation. These results were consistent with Raman and x‐ray photoelectron spectroscopy (XPS) data previously obtained in our laboratory.
X‐ray photoelectron spectroscopy investigation of pumice‐supported nickel catalysts
Authors: Venezia A. M. , Bertoncello R. , Deganello G.
Published: December 2004

Pumice‐supported nickel catalysts, prepared by the method of slow homogeneous precipitation with urea, were analysed by x‐ray photoelectron spectroscopy (XPS). By comparison with similarly prepared silica‐ and alumina‐supported nickel catalysts, a preferential interaction of Ni2+ with Al3+ of the support has been determined. A quantitative XPS analysis indicated large segregation of nickel to the surface. The treatment with H2 at 673 K and 1073 K produced a partial reduction of Ni+2 to Ni0. The extent of the reduction was largest at 1073 K and in this case the reduced Ni in the metallic phase was detectable by x‐ray diffraction. A decrease of the Ni 2p/Si 2p intensity ratio occurring in the lower temperature H2‐treated catalysts was attributed to diffusion of nickel as Ni2+, as a consequence of a solid‐state reaction between nickel ions and support oxides, whereas the decrease of the intensity ratio in the high‐temperature reduced catalysts was attributed to sintering of the nickel particles and to diffusion of nickel atoms interacting with oxygen vacancies of the support.
Interfacial layers formed during the moulding of nitrile butadiene rubber compounds: Influence of carboxylic acid residues on adhesion
Authors: Reeves L. A. , Kiroski D. , Packham D. E.
Published: December 2004

The mould release of nitrile butadiene rubber is strongly influenced by residues from the polymer and compounding ingredients that form an interfacial layer during moulding. Carboxylic acid residues may comprise an important part of this layer. There are two potential sources of these: emulsifier residues in the base rubber and ‘stearic acid’ added during compounding. Generally the mould adhesion decreases as the carboxylic acid concentration increases, but residues from longer chain acids, such as stearic acid, reduce adhesion to a greater extent than do those from shorter chain acids such as lauric acid. Evidence from XPS and SIMS shows that residues from both can come to the interface, but rheological results indicate that the latter are less easily sheared and so are associated with higher mould sticking.
Influence of formulation chemistry on the locus of failure of adhesive joints
Authors: Taylor A. M. , McLean C. H. , Charlton M. , Watts J. F.
Published: December 2004

The durability of photocured resins adhered to ceramic substrates has been investigated. Monochromated XPS and time‐of‐flight SIMS were employed to determine the precise locus of failure in butt‐joints comprised of a photocured resin adhered to either a 96% pure, debased alumina substrate or single‐crystal silicon. Prolonged (> 14 days) immersion in water at 50°C resulted in cohesive failure, with 1–2 nm of polymer remaining on one of the ceramic substrates. An absence in the spectrum of any components attributable to characteristic groups from a major constituent of the polymer within this overlayer suggested the possibility that one of the minor resin components was aggregating at the organic/inorganic interface to produce an in situ weak boundary layer. The interactions of some of the organic molecules present in the formulation with the α‐alumina substrate were investigated using molecular modelling techniques to indicate the most favourable interactions with the substrate. Durability studies were also carried out on a reformulated photocured resin to investigate the effect of removal of the ethoxylated methacrylate monomer, suspected of being the principal organic component at the weak boundary layer, on both joint performance and locus of failure.
Use of matrix corrections in the calculation of surface composition of AgPd alloys in auger electron spectroscopy
Authors: Reniers F.
Published: December 2004

The surface segregation in binary alloys is often studied by Auger electron spectroscopy. However, the information obtained in the Auger spectra is representative of a region thicker than one monolayer. The Auger signal must be decomposed into the contributions of the different atomic layers. On the other hand, it is now well known that matrix correction factors must be used to relate the intensity of the Auger signal to the composition of the sample. As these two parameters are seldom put together in the treatment of Auger data, we tried to combine them for the study of the surface segregation in silver–palladium alloys. We calculated the matrix correction factors for AgPd alloys in the whole range of concentrations. The attenuation length corrections and the backscattering corrections were calculated on the basis of different models (Seah and Dench, Penn, Tanuma–Powell–Penn, Ichimura–Shimizu–Langeron, Reuter–Ichimura, etc.). The matrix corrections were compared to the Hall and Morabito approach and with previously published results. The matrix corrections were then introduced into a layer‐by‐layer model of interpretation of the Auger signal. While the surface composition calculated without matrix correction reveals silver enrichment relative to the bulk of the samples, the use of matrix corrections lead to an enrichment in silver that is strongly attenuated.
Combined atomic force‐, friction force‐ and local elasticity microscopy on ReS2 crystals: Surface topography and material contrast
Authors: Schimmel Th. , Friemelt K. , Lux‐Steiner M. , Bucher E.
Published: December 2004

Crystal surfaces of the layered dichalcogenide semiconductor rehenium disulphide (ReS2) grown by the vapour‐phase transport technique were investigated by combined atomic force microscopy (AFM), lateral (friction) force microscopy (LFM) and force modulation (local elasticity) microscopy as well as scanning electron microscopy (SEM). The as‐grown crystals exhibit atomically flat surfaces, on which circular islands with a typical diameter of 0.3 μm and a height of 30–50 nm have grown. While AFM only yields the topographic information, the simultaneously recorded lateral force and force modulation images give a clear material contrast, showing that on the islands the lateral forces are higher and the local elasticity is lower than on the bare ReS2 surface. The dependence of both the topographic and the lateral force images on the scanning direction is investigated. The results indicate that during crystal growth a different material, presumably ReBr3, has segregated on the surface of the ReS2 crystals. It is demonstrated that AFM in combination with LFM and force modulation microscopy can provide information on the composition of heterogeneous samples as well as the local mechanical properties of the different components.
Atomic force microscopy investigation of argon‐bombarded InP: Effect of ion dose density
Authors: Demanet C. M. , Malherbe J. B. , van der Berg N. G. , Sankar Vijaya
Published: December 2004

Samples of InP(100) n‐doped with S atoms to 4 × 1018 cm−3 and to 6 × 1018 cm−3 were bombarded with 0.5 and 5 keV argon ions. The angle of incidence of the 5 keV ions was 71° with respect to the sample normal and 41° for the 0.5 keV ions. The resulting topography development was investigated by means of atomic force microscopy (AFM) and transmission electron microscopy (TEM) of Cr–C replicas of the bombarded surfaces. There was a correlation between the AFM images and those from the TEM replicas. At the same magnification the AFM images showed more detail. The surface roughness in the AFM images and those from the TEM replicas. At the same magnification the AFM images showed more detail. The surface roughness in the AFM images was quantified using the software of the AFM instrument. In the range 5 × 1014−2 × 1018 Ar+ cm−2, there was a linear relationship between the roughness parameter and the logarithm of the ion dose density. This fact excludes a seeding sputter erosional theory for the explanation of the development of bombardment‐induced topography on InP. At the higher does densities, ripple formation was observed. The dose density dependence of average wavelength of the ripples did not correlate with the predictions of the Bradley–Harper theory.
Fast simulation of XPS and AES spectra by transformations of electron trajectories
Authors: Alkemade Paul F. A.
Published: December 2004

A new Monte Carlo simulation model is presented for the calculation of XPS or AES spectra of homogeneous or near‐homogeneous solids. The model is at least one order of magnitude faster than conventional simulation models. The increase in computation efficiency is obtained by translations and rotations of simulated electron trajectories.

Simulations have been applied to evaluate a number of models for inelastic and elastic scattering. In addition, a successful comparison is made between simulated and measured XPS spectra of Al and of Ag over a range of 600 eV.
Electronic structure of tin oxides: High‐resolution study of XPS and Auger spectra
Authors: Kövér L. , Kovács Zs. , Sanjinés R. , Moretti G. , Cserny I. , Margaritondo G. , Pálinkás J. , Adachi H.
Published: December 2004

High‐resolution core and valence band photoemission as well as photoinduced Auger spectra of metallic Sn, polycrystalline SnO and SnO2 ((110) natural single‐crystal cassiterite and polycrystalline) samples were measured in order to give information on local electronic and geometric structures around the core‐ionized atoms and for providing data for facilitating quantitative analysis of systems containing these species. The SnO surfaces were obtained without the use of ion sputtering by using a special preparation procedure based on in vacuo surface scraping. The respective experimental valence band spectra could be utilized in quantitative analysis of layered tin oxide structures. Valence band spectral shapes are compared to spectra calculated by using a cluster‐type (DV‐Xα) MO model. From the Sn Auger parameter measurements, using a simple electrostatic model, the similarity of the initial‐state effects for the two oxides was deduced, while the oxygen Auger parameter values indicated large polarizability and the respective final‐state hole–hole repulsion energies were determined.
Realistic cluster approach for interpreting the valence band structure of phosphorus oxyanions
Authors: Cserny I. , Kövér L. , Némethy A. , Adachi H. , Tanaka I. , Sanjinés R. , Coluzza C. , Margaritondo G.
Published: December 2004

The electronic structures of different phosphates were studied by using the DV‐Xα cluster molecular orbital method. Experimental data on crystal structures from x‐ray diffraction measurements were used to set up realistic model clusters. Theoretical XPS valence band spectra obtained from the DV‐Xα calculations were compared to our high‐resolution XPS measurements on polycrystalline powder Li3PO4, Na3PO4, Na4P2O7 and (NaPO3)n samples. These new measurements made possible a more rigorous test of the theoretical approach and more reliable shape analysis than the previous set of data obtained by non‐monochromatized measurements combined with the resolution enhancement technique. Systematic study of different clusters showed that the cations around the PO4 cluster and the distortion of the PO4 tetrahedra due to the anisotropic crystal forces play only a minor role and their influence on the valence band spectra was found to be negligible. In the case of polyphosphates, considerable changes were found in the valence band spectra as a consequence of small changes in the bond angle of the P—O—P bridges. Our results, based on cluster parameters specific to the anhydrous crystals, are in good agreement with the experiments.