bluuebunny/crossref_metadata_2025 huggingface dataset:
Optical Characterization of Silicon Oxynitride Thin Films by Variable Angle Spectroscopic Ellipsometry
Authors: Xiong Yi‐Ming , Snyder Paul G. , Woollam John A. , Al‐Jumaily G. A. , Gagliardi F. J. , Mizerka L. J.
Published: May 2005

Silicon oxynitride (SiOx Ny) thin films were deposited on silicon substrates by ion‐assisted deposition. Variable angle spectroscopic ellipsometry (VASE) was used to optically characterize the deposited film properties, such as layer thickness and composition, film surface and interface qualities, as well as the retractive index spectrum in the wavelength range 320–820 nm. The measured VASE spectra were analyzed by assuming SiOx Ny to be a physical mixture of two distinct phases, silicon dioxide and silicon nitride, using the Bruggeman effective medium approximation. Remarkably good agreements between the measured spectra and model calculations were obtained over the entire spectral range for all the samples studied. Layer thicknesses of SiOx Ny films determined by VASE were consistent with their corresponding nominal values. The ellipsometrically deduced refractive index spectrum was observed to be strongly dependent on the film composition. In addition, the film refractive index at each applied wavelength was found to be a linear function of its constituent relative volume fraction. The results from VASE analysis also indicated that all the sample films investigated exhibited smooth surfaces, sharp interfaces between the film and substrate and high packing density.
Characterization of epitaxial SiGe thin films on Si: Analytical considerations
Authors: Evans K. L. , Anderson T. A. , Liaw M. , Gregory R. , Munukutla L. V. , Graham R. J. , McCartney M. R.
Published: May 2005

Epitaxial silicon—germanium (SiGe) thin films are being developed for a number of interesting applications. Potential uses include applications as fabrication layers for heterojunction bipolar transistor devices and a number of other novel electronic devices. For device applications, SiGe structures offer the potential for increased speed, bandgap engineering, rapid oxide growth and low processing temperatures.

For electronic device applications, successful fabrication of SiGe films with the desired properties requires a thorough understanding of deposition, oxidation, interdiffusion and interface behavior. This paper details the analytical methods employed to characterize SiGe thin films deposited in various molecular beam epitaxy (MBE) and chemical vapor deposition (CVD) reactor systems. Rutherford backscattering spectrometry (RBS), secondary ion mass spectrometry (SIMS), Auger electron spectroscopy (AES) and transmission electron microscopy (TEM) are used to study both the as‐deposited and oxidized films.

Determination of Ge content and distribution, measurement of dopant concentrations within the SiGe, build‐up of Ge at oxide interfaces, build‐up of oxygen at interlayer interfaces and film thickness measurements will be illustrated. Methods for the cross‐correlation and calibration of the various instrumental techniques and use of the characterization data to optimize processing conditions will also be discussed.
Quantification of surface hydroxides using chemical labeling and XPS
Authors: Dang Tuan A. , Gnanasekaran R. , Deppe Denise D.
Published: May 2005

XPS when used in conjunction with silylation can determine surface hydroxide. The penetration depth was studied using DRIFT and various silylation conditions. Application of this technique to many different inorganic matrices, including Si3N4, glass, silica thin film, zinc silicate lamp phosphor and Al2O3, is illustrated.
Surface oxidation of silicon carbide platelets as studied by x‐ray photoelectron spectroscopy and bremsstrahlung‐excited Auger electron spectroscopy
Authors: Wang Pu Sen , Malghan Subhas G. , Hsu Stephen M. , Wittberg T. N.
Published: May 2005

X‐ray photoelectron spectroscopy (XPS) and Bremsstrahlung‐excited Auger electron spectroscopy (XAES) were used to study the surface composition and oxidation of silicon carbide platelets which had been heated in air at 500–800° C. The surface oxide thickness for each heating time and temperature was calculated independently from the SiO2/SiC intensity ratios in both the Si 2p XPS and the Si KLL XAES spectra. The results from these two methods agreed to within our calculated experimental error. Both methods revealed that the oxidation rate was non‐linear and non‐parabolic in this temperature range. Boron oxide was observed on the SiC platelets after heat treatment. Boron is used by the manufacturer as a catalyst and remains as an impurity in the SiC platelets.
AES determination of compositional variation in LPCVD tungsten silicide films in confined spaces
Authors: Rogers B. R.
Published: May 2005

Compositional variation in chemical vapor deposited tungsten silicide films in confined spaces has been studied using scanning Auger electron spectroscopy. ‘Infinitely’ long silicon trenches with aspect ratios ranging between 1.5 and 5 were used to define the confined space. Composition changes down the sidewall of a partially filled trench were determined by cleaving the sample along the length of a trench and analyzing specific points down the sidewall. The samples were lightly sputtered before analyzing to remove the native oxide and reach a uniform composition of the silicide. The sample was carefully positioned during sputtering to minimize any redeposition of material onto the analysis area due to sputtering of adjacent surfaces. Using this method the silicon content of the silicide was shown to increase as a function of distance from the surface. This spatial variation in film composition qualitatively agrees with the predictions of a computer simulation of the deposition process.
A tandem SIMS study of poly(vinyl methyl ether)
Authors: Leggett G. J. , Chilkoti A. , Ratner B. D. , Vickerman J. C.
Published: May 2005

Results are presented for a tandem‐SIMS investigation of the fragmentation patterns of secondary ions sputtered from the surface of poly(vinyl methyl ether) (PVME). A complete fragmentation sequence is deduced which is capable of explaining the formation of most of the major ions observed in the SIMS spectrum in terms of fragmentation steps proceeding from the largest secondary ion observed. The fragmentation steps involved in the formation of these ions are discussed and the secondary ion structures are identified.
Towards a universal curve for electron attenuation: Elastic scattering data for 45 elements
Authors: Werner W. S. M.
Published: May 2005

The attenuation parameter (AP), which quantitatively describes the influence of elastic electron scattering on the electron spectroscopies, has been calculated for 45 elements (Be, C, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Sr, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, Ba, La, Hf, Ta, W, Re, Os, Ir, Pt, Au, Pb) and for energies of 250, 500, 1000 and 1500 eV. The calculations were performed with a Monte Carlo algorithm in which elastic scattering is modelled by use of the partial wave expansion method. The results show a linear relationship between the AP and the inelastic mean free path (IMFP), and a linear least‐squares fit of the data provides a simple formula to calculate the AP for a given material and energy. The depth distribution function (DDF), which in the most general sense discribes the attenuation properties of signal electrons, can be calculated analytically using this AP. The possibility of using the calculated AP values in combination with this DDF to extract IMFP data from an overlayer experiment has also been explored. Evidence is found, and discussed, that the presentedalgorithm can be used to convert IMFPs to attenuation lengths (AL).
Investigation of sputter‐induced surface composition modification during in‐depth profiling of implanted materials by sims, XPS and AES
Authors: Darque‐Ceretti E. , Aucouturier M. , Boutry‐Forveille A.
Published: May 2005

Depth profile analysis by SIMS (secondary ion mass spectrometry), XPS (x‐ray photoelectron spectroscopy) and AES (Auger electron spectroscopy) have been performed on copper‐implanted monocrystalline silicon and zinc‐implamented polycrystalline copper under various ion sputtering conditions. A comparison of the different composition profiles shows an important influence of the ion sputtering parameters and of the analysis method on the apparent distribution of the implanted impurities.

The results can be interpreted in terms of variations of the surface or subsurface composition during sputtering, taking into account preferential sputtering and/or sputter‐induced segregation phenomena. An unexpected improvement of ionization yields owing to contaminating oxygen may also induce artefactal modifications during the transitory sputtering period. The analysis of sputtered matter (SIMS) under O2 sputtering appears to be the most reliable analysis method, although the results, even in that case, can be altered by segregation phenomena.

A comparison of the sputtered matter and the surface analysis method leads to the experimental determination of differential sputtering ratios for both systems.
Charge stabilization and ion trapping under specimen isolation conditions during Sims analysis
Authors: van der Heide P. A. W. , Metson J. B. , Lau W. M.
Published: May 2005

Specimen isolation (SI), an extreme form of kinetic energy filtration, has been shown to be an effective tool for controlling the problems of sample charging and molecular interferences often encounted in secondary ion mass spectrometry (SIMS). In this study the mechanisms involved in the charge stabilization, under both positive and negative primary beam bombardment, were examined more closely. This was facilitated by the introduction of a resistor into the SI configuration, allowing for in situ sample potential control, and the use of computer simulations. The formation of low‐energy ion traps at the sample surface under extreme SI conditions was also directly recorded, showing good agreement with the computer simulations carried out.
Study of interface diffusion of Ti and TiN PVD layers by Bremsstrahlung‐induced AES
Authors: Meisel W. , Hanzel D.
Published: May 2005

The influence of heat treatment in ultrahigh vacuum (UHV) on Ti and TiN layers coated by physical vapour deposition (PVD) has been studied by AES, XPS and bremsstrahlung‐induced AES. It could be concluded that up to 500° C (1 h) the Ti layer does not change significantly. At the TiN/steel substrate interface, however, a counterdiffusion of nitrogen and adventitious oxygen takes place, resulting in partial nitridation of the steel substrate and oxidation of the coating.
Random uncertainties in AES and XPS: II: Quantification using either relative or absolute measurements
Authors: Cumpson P. J. , Seah M. P.
Published: May 2005

Often, peak intensity measurements are quantified by using relative sensitivity factors to give the composition of a surface in percentage terms. This process affects the estimation of uncertainties; the uncertainty in the final quantification depends in a complex way on a sum involving the squares of the uncertainties in the measures for each element.

We examine quantification in detail, and apply Bayesian statistical methods to this problem for the first time. We find that if the intensities are quantified by an absolute method rather than a relative one, the final uncertainties involve sums of the reciprocals of the squares of these individual uncertainties. Thus, the combination of uncertainties in quantification by an absolute method can improve the accuracy of the final quoted composition, whereas the combination of uncertainties in quantification by sensitivity factors always reduces the accuracy.
An area ratio method for RBS compositional analysis of thin films
Authors: Kusao Kenji , Satoh Minoru , Morita Kenji
Published: May 2005

A simple and practical approach to determine the composition of binary thin films by RBS is proposed. It is shown in the single collision approximation that the composition ratio m/n of a uniform binary film Am Bn is determined with sufficiently high accuracy by the ratio between the peak areas AA/AB in the RBS spectrum and that the ratio AA/AB is not essentially influenced by the energy of the incident ion beam, the thickness of the film or the stopping power. The factor that is most sensitive to the accuracy is shown to be the statistical error in the total counts of peak areas AA and AB. It is experimentally demonstrated with an AlCu alloy film deposited on polycarbonate that the composition can be determined within an error of 0.63%.
Reactions of Au or Cr evaporated on Si wafers measured by the refracted x‐ray fluorescence method
Authors: Shoji T. , Hirokawa K.
Published: May 2005

Measurement of the x‐ray fluorescence intensity vs. take‐off angle distribution curve by the refracted x‐ray fluorescence method was used to investigate surface reactions of Au or Cr thin film evaporated on Si wafer substrates. The Au rapidly reacted at 440°C for 5 min, and Cr formed a silicide by annealing at 700°C for 3 h in a vacuum of 4 × 10−7 Torr. Thus, the method could be applied as an effective technique to study solid‐state reactions.
Technique for XPS measurements of volatile adsorbed layers: Application to studies of sulphide flotation
Authors: Kartio I. , Laajalehto K. , Suoninen E. , Karthe S. , Szargan R.
Published: May 2005

A system for treating XPS samples containing easily volatile and reactive adsorption layers is described. Desorption and reactions with atmospheric gases prior to the measurement are avoided by repeated exposure of the sample to an inert atmosphere at room temperature followed by cooling to liquid nitrogen temperature and subsequent evacuation to spectrometer vacuum.

The method has been applied to pyrite (FeS2) samples treated in aqueous potassium ethyl xanthate (dithiocarbonate) solutions. In agreement with previous indirect predictions of infrared and electrochemical measurements, the results confirm, under certain conditions of sample preparation, the presence of dixanthogen adsorption layers on FeS2 that have not been found previously on XPS measurements.

Application of the method to surface studies related to sulphide flotation is especially important because of the volatility of several species possibly existing in the collector adsorption layer. Other potential applications are corrosion and catalysis studies.
An XPS and AES study of the ageing of a Co–20%Ni metal‐evaporated tape
Authors: Mitton D. B. , Walton J. , Thompson G. E.
Published: May 2005

The initial oxidation behaviour of a Co–20%Ni alloy exposed to air and the longer term oxidation of a metalevaporated magnetic recording tape (MET) of the same composition have been studied using XPS and AES.

Air exposure of the alloy for 24 h showed the formation of a mixed hydroxide/carbonate layer over a relatively small amount of oxide. The hydroxide‐containing layer was composed of both Co(OH)2 and Ni(OH)2, with the outer surface enriched in Co(OH)2. The carbonates are believed to originate from the hydration of carbides present in the alloy. Analysis of MET showed the presence of the oxides Co3O4 and NiO in addition to the hydroxides and carbonates.

An Auger depth profile through MET indicated the presence of significant oxygen below the surface oxide, which increased in concentration towards the metal/polymer interface. This is explained by penetration of oxygen/water vapour into both voids and cracks formed during the manufacturing process.
Surface study of a chromate pretreatment before coil coating of Al–43.4Zn–1.6Si coated steel
Authors: Hörnström S. E. , Hedlund E. G. , Klang H. , Nilsson J.‐O. , Backlund M.
Published: May 2005

Chromating is frequently used for temporary corrosion protection and as a pretreatment before organic coating of aluminium, zinc and aluminium/zinc alloys. In this work we have studied the composition and the chemical state of pretreated Al–43.4Zn–1.6Su‐coated strip steel. Auger and x‐ray photoelectron spectroscopy were used to characterize the surface of samples exposed to the chemicals from the different processing steps. In the first step, which is alkaline cleaning, hydroxy ions in the cleaner dissolve aluminium oxide from the surface of the strip and make the surface richer in zinc. In the chromating step that follows, the chromic acid causes dissolution of Al and Zn from the surface and precipitation of a complex chromium hydroxide layer containing small amounts of fluoride, aluminium, tungsten and molybdenum ions. Chromium exists in the valance states Cr3+ and Cr6+. In the final pretreatment step, which consists of a chromic acid after‐rinse, additional, mainly hexavalent, chromium is deposited. The chromate coating is thicker in regions indented by the temper rolling than in surrounding areas. The temper rolling, which is performed with textured rolls after metallization of the strip, breaks the surface aluminium oxide film and increases the reactivity of indented regions. The chromate coating is also thicker in the Zn‐rich interdendritic regions than on the Al‐rich dendrite arms. This is probably due to the microstructure of the metal coating in interdendritic areas.
Reaction of aniline with chemisorbed pyromellitic dianhydride on Cu(110): A model for controlled organic film growth
Authors: Frederick B. G. , Richardson N. V. , Unertl W. N. , El. Farrash A.
Published: May 2005

The reaction of aniline with pyromellitic dianhydride (PMDA) chemisorbed on Cu(110) has been followed by high‐resolution electron energy‐loss spectroscopy (EELS) and XPS. The PMDA is adsorbed via opening of one anhydride ring to permit a strong carboxylate link to the copper surface but with an unperturbed anhydride unit directed away from the substrate. The reaction with aniline takes place in a two‐step process: formation of an amic acid intermediate; and loss of H2O with heating to 440 K, leading to the imide. The process demonstrated here is a model reaction that represents a successful initial step in the growth of complex, tailored, organic thin films by the sequential deposition/reaction of carefully selected bifunctional molecules, starting with a clean, well‐defined, single‐crystal substrate. One functionality of the molecule is used to bond to the growing film and the second provides the terminating surface ready to accept the next molecular layer.
Surface modification of plastics by plasma treatment and plasma polymerization and its effect on adhesion
Authors: Carlsson C. M. Gilbert , Johansson Kenth S.
Published: May 2005

The Adhesion between plasma‐modified polyethylene (PE) and different polar polymers, as well as aluminium and steel, has been studied. The PE was modified by either oxygen plasma treatment or plasma polymerization of acrylic acid. The result show the importance of introducing polar groups on the surface of the non‐polar PE in order to improve the adhesion to polar polymers as well as metals. Laminates made of plasma‐modified PE ad polyamide 6 (PA‐6) or poly(ethylene vinyl alcohol) (EVAL‐G) showed failure in PA‐6 or EVAL‐G when delaminated. Poly(ethylene terephthalate) (PET), which is not as polar as PA‐6 or EVAL‐G, showed an adhesive failure when the PE was treated with either of the plasma methods. However, when both the PET and the PE were modified, the failure occurred in the PET upon delamination. Oxygen plasma treatment of PE resulted in an increased adhesion when laminated with cellophane, with no observed material failure. The laminates composed of plasma‐modified PE and aluminium or steel showed cohesive failure in the PE.
ToF‐SIMS and XPS studies of the interaction of silanes and matrix resins with glass surfaces
Authors: Wang D. , Jones F. R.
Published: May 2005

The interface between glass, glass fibres and epoxy resin in a composite has been studied using time‐of‐flight secondary ion mass spectrometry in static and scanning modes in combination with x‐ray photoelectron spectroscopy. The presence of a multilayer of the polymeric hydrolysed γ‐aminopropyltriethoxysilane (HAPS) on the glass surfaces has been confirmed. After extraction with hot water or toluene only a monomolecular interfacial layer of HAPS is chemically bound to the immediate glass surface through siloxane bonds, leaving the amino groups at the outer surface and available for reaction. It has been demonstrated that this interfacial layer plays an essential role in the coupling reaction between the amino group of the HAPS deposit and the epoxide group of the epoxy resins, diglycidyl ether of bisphenol A or S (DGEBA or DGEBS). These interfacial reactions were complicated by the presence of polydimethylsiloxane and the incorporation of substrate aluminium into the HAPS deposit. The aluminium sites appeared not to be involved in the coupling reaction.
Evaluation of AES depth profiles of thin‐film systems by application of novel graphically interactive factor analysis software
Authors: Scheithauer U. , Hösler W. , Riedl G.
Published: May 2005

Factor analysis has proved to be a powerful tool for the full expolitation of the chemical information included in the peak shapes and peak positions of spectra measured during AES depth profiling. Owing to its ability to extract the number of independent chemical components, their spectra and depth distributions, it is increasingly used in routine analysis. However, one has to be aware of the crucial role of the analyst in selecting the physically relevant result from the indefinite number of mathematical solutions. For this reason, he must be put in a position to define the matrix rotation and to check the resulting factors in a fast, flexible and transparent way. Therefore, factor analysis software offering a graphically interactive user interface has been devleoped. During the necessary rotations in factor space both the depth distributions and the corresponding spectra are displayed simultaneously, so that the analyst can judge the physical relevance of the solution and can quickly respond with the necessary adjustments.

To demonstrate the capabilities of the software in the evaluation of AES depth profile data, a TiN/Ti/SiO2 layer sequence form microelectronics technology was chosen. As an important result, additional layers are recognized at the interfaces. This example demonstrates the advantages of factor analysis and emphasizes the necessity of the analyst's knowledge on both AES spectra and hte investigated material systems. In addition, it shows the importance of a fast, direct, transparent and interactive interface between the analyst and the mathematical tool of factor analysis.
Photoelectron and ion scattering spectroscopy of zeolites under reduced surface‐charge conditions
Authors: Grünert Wolfgang , Schlögl Robert , Karge Hellmut G.
Published: May 2005

For zeolites that exhibit ion conductivity, the surface charge in the application of surface spectroscopy (XPS, UPS, ISS) may be significantly reduced by using elevated measurement temperatures. On this basis, a measurement technique has been developed that allows the application of ISS and UPS to zeolites and the detection of differential charging effects in XPS. Both the new perspectives and the limitations of this technique are illustrated by examples of Y zeolites exchanged with lanthanum and with silver.
A method to subtract the transmission and dispersion analyser effect from high‐intensity, low‐resolution XPS spectra
Authors: Battistoni Claudio , Mattogno Giulia , Righini Guido
Published: May 2005

The quality of XPS and AES data in terms of both peak position and intensity is critically dependent on the experimental conditions. It is known that when using the electron energy analyser‐detector system under different experimental conditions, the relative intensity peak ratios change remarkably. The knowledge of the energy dependence of the spectrometer's intensity response function is important for quantitative analyses.

In order to handle experimental conditions (e.g. small‐area XPS) a methodological procedure to estimate the effect of individual parameters is proposed. According to this procedure the spectra are manipulated using a modified deconvolution routine that contemporaneously takes into account the relative transmission function and analyser broadening function.
Sudden surface roughening followed by levelling observed in SIMS analysis of InP‐containing III–V multilayers
Authors: Miethe K. , Kuphal E.
Published: May 2005

An epitaxially grown III‐V multilayer system with an InP overlayer (80 nm thick) subjected to secondary ion mass spectrometry (SIMS) depth profiling was found to develop an extreme topography in the overlayer. As this topography was levelled in subsequent layers an improvement of depth resolution with depth was observed in the SIMS profile. The topography features seen by scanning electron microscopy on the InP overlayer agree with those reported and interpreted previously for bulk InP. Here, the fact is emphasized that during SIMS analysis extreme topography is likely to develop even on thin layers of InP, but that topography levelling (as described extensively in earlier work) may lead to an improvement of depth resolution if further layers of InP are absent.
Auger electron spectroscopy and principal component analysis of the first stages of oxidation in GaAs(100)
Authors: Passeggi M. C. G. , Vaquila I. , Ferrón J.
Published: May 2005

The first stages of oxidation in GaAs(100) have been studied using Auger electron spectroscopy and principal component analysis. We found that at low oxygen exposures (<104 Langmuirs) and in the presence of excited oxygen produced by electron bombardment, GaAs oxidizes via a one‐phase process only. This phase involves the simultaneous oxidation of both the elements Ga and As.
Quantitative XPS analysis of leached layers on optical glasses
Authors: Sprenger D. , Bach H. , Meisel W. , Gütlich P.
Published: May 2005

The corrosion of optical glasses often reduces the utility of uncoated glasses as well as the adhesion of resistive coatings deposited onto corroded glasses. Photoelectron spectroscopy (XPS) was applied to study glass surfaces with respect to their surface corrosion. In particular, leaching by the influence of polish slurries, pure water, air and even residual gases inside a vacuum device was studied in detail. Pure quartz glass and different sodium and barium silicate glasses were broken in ultrahigh vacuum (4 × 10−10 mbar) for the determination of sensitivity factors of the different XPS signals. It was found that a quantitative determination of the surface composition of corroded and leached layers is possible by determination of the intensities of the XPS O 1s, Si 2p, Si 2s, B 1s, Na 1s, Na 2s, Na 2p, Ba 3d and Ba 4d signals. After leaching in aqueous solutions, the barium is exchanged by hydrogen via an interdiffusion mechanism, resulting in an enrichment of different hydrogen bonds (H2O/H3O+, OH−, SiOH) in the leached layer. An iterative algorithm is shown, which allows, in addition to the content of all other elements, the hydrogen content to be determined quantitatively in the leached layers. Furthermore, the calculation of the density of surface layers becomes possible. For an exact analysis of the leached layers the intensity loss by contamination layers is considered and the calculated density is used to perform matrix‐dependent intensity corrections for the attenuation length.
Etchant for chemical thinning of InP and its application in the fabrication of InP diffused junction solar cells
Authors: Faur Mircea , Faur Maria , Jayne D. T. , Bailey S. , Goradia M.
Published: May 2005

A new etchant, which we have called ‘PNP’, with the composition (o‐H3PO4)u: (HNO3)v: (H2O)(2)t: (H2O)100−(u+v+t)has been developed for thinning, after contacting, the n+and p+emitter layer of n+p and p+n InP structures made by thermal diffusion. By varyingu,vandt, reproducible etch rates of 5–10 nm min−1have been obtained. After thinning the 2.5–4.5 μm thick p+InP layer down to 60–250 nm, specular surfaces have been obtained at up to 80 nm min−1etch rates. Owing to its intrinsic qualities, the residual phosphorus‐rich oxide after thinning the emitter layer provides surface passivation of p+InP surfaces and can also serve as a first‐layer antireflective coating. Very high quality p+n InP structures were also obtained using a thin (30–40 Å thick) phosphorus‐rich chemical oxide, grown using this etchant as a diffusion cap layer.
X‐ray induced AES study of the effect of chemically bound hydrogen on the oxidation kinetics of an Si3N4 powder
Authors: Wang Pu Sen , Malghan Subhas G. , Hsu Stephen M. , Wittberg Thomas N.
Published: May 2005

Silicon nitride powders manufactured by the pyrolysis of silane and ammonia were found to contain chemically bound hydrogen. Most of this hydrogen could be removed by vacuum annealing at 1000°C. In the present study, x‐ray‐induced AES has been used to determine the oxidation kinetics for vacuum‐annealed Si3N4 powders that were heated in air at temperatures between 850 and 975°C. The average oxide thickness on the surface of the powder particles for each temperature and oxidation time was calculated from the ratio of the SiO2 to Si3N4 Si KLL peak intensities. The results are compared with those for the as‐manufactured powder, which contained the hydrogen impurity. For both annealed and unannealed powder, the oxidation rate was linear within the temperature range 850–1000°C. Within this temperature range, the oxidation rate was significantly higher for the vacuum‐annealed Si3N4 powder.
Compositional analysis of CdS/SnO2 films after heat treatments and CdCl2 pretreatments
Authors: Swartzlander Amy B. , Niles David W. , Hasoon Falah S. , Al‐Jassim Mowafak M.
Published: May 2005

We used Auger electron spectroscopy (AES) to perform a systematic study of CdS thin films grown from solution on SnO2‐coated glass. The effects of heat treatments and CdCl2 pretreatments on the stoichiometry of the CdS and the diffusivity of the CdS/SnO2 interface have been investigated. The results show that CdS thin films not treated in CdCl2 become sulphur‐deficient with heat treatments above 350°C, where CdS thin films treated in CdCl2 must be heated above 350°C to be smooth and stoichiometric. We did not observe interdiffusion of atomic species at the CdS/SnO2 interface after heat treatments of 350, 450 or 550°C.
Use of image depth profiling SIMS for the study of tinplate corrosion
Authors: Lu S. F. , Mount G. R. , McIntyre N. S. , Fenster A.
Published: May 2005

Four tinplate specimens with different corrosion properties were studied using secondary ion mass spectrometry (SIMS) image analysis. The continuity of the structure of the interfacial iron‐tin alloy was able to be examined using a volume rendition computer program, which generates a three‐dimensional representation of the stack of ion images. The surface coverage of tinplate was found to vary widely on some specimens; those exhibiting poor corrosion characteristics were found to have little or no elemental tin covering the raised regions between the rolling grooves.
Calibration procedure for quantitative surface analysis by total reflection X‐ray fluorescence
Authors: Torcheux L. , Degraeve B. , Mayeux A. , Delamar M.
Published: May 2005

Total reflection x‐ray fluorescence analysis (TXRF) is a new technique able either to achieve elemental analysis of microquantities deposited on a very flat reflecting surface or to detect very low levels of surface contamination on reflecting substrates like silicon wafers. In this paper we report a calibration procedure to achieve an impurity quantification in the range of one hundredth of an atomic monolayer and below.

To reach this goal, it is necessary to distinguish between two types of surface deposits: submonolayer surface atoms and particulate matter deposited onto the reflector surface. We show how these two situations can be differentiated, both theoretically and experimentally.

For surface contamination, calibration curves were obtained from nickel submonolayer standards prepared by a method of quantitative contamination. These standards were certified by Rutherford backscattering analysis (RBS). Results show that linear regression is suitable for calibration. For elements other than nickel it is shown that the correlation between TXRF and RBS is good, except for concentrations of <5 × 1011 atoms cm−2. This is mainly owing to the difficulty of obtaining certified low contamination levels with RBS. Quantification limits for TXRF analysis are found to be extremely low in comparison to most surface analysis techniques, and TXRF is able to detect metallic impurities like Fe, Ni, Cr, Zn and Cu at ∼2 × 1010 atoms cm−2 in a short time (1000 s) without any sample preparation.
SIMS–RBS depth profiling of silver‐diffused glass systems
Authors: Quaranta A. , Gonella F. , Caccavale F. C. , Brusatin G.
Published: May 2005

Both SIMS and RBS techniques are used to obtain smooth accurate concentration profiles of silver diffused into soda‐lime glass systems. By a computer simulation, a combination of the two techniques enables more detailed information to be obtained on the silver distribution at a depth of up to several micrometres, and the concentration profiles can be used effectively for testing the reliability of some optical behaviour characterizations of glass waveguiding structures.
Time‐of‐flight secondary ion mass spectrometry of polybutadienes
Authors: Hittle Lucinda R. , Hercules David M.
Published: May 2005

High resolution time‐of‐flight secondary ion mass spectrometry was used to study a series of polybutadienes with molecular weights between 400 and 170 000 Da. The number‐averaged and weight‐averaged molecular weights of polybutadienes with molecular weights of <5000 Da were determined and showed reasonable agreement with values obtained by conventional methods. Samples with molecular weights of >5000 Da showed primarily fragments in the mass range 500–4000 Da, resulting from main chain cleavage of CC single bonds. A fragmentation model based on simple statistical chain cleavage was used to explain the fragmentation patterns observed in the spectra. These fragmentation patterns contained Rn, +Δ, +2Δ and −Δ species, where Rn represents an integral number (n) of repeat units and Δ is a methylene group. The relative intensities of these clusters as a function of sample molecular weight and cluster size were studied, and were the same regardless of polymer size. The fine structure of the fragment clusters was also examined, and the mechanisms responsible for their formation are discussed.
Degradation of cleaved LnSb(Ln = La, Ce) by reaction in ultrahigh vacuum and air
Authors: Oku Masaoki , Suzuki Takashi
Published: May 2005

The degradation of LaSb and CeSb in ultra high vacuum and air has been studied by XPS. The exposure of the surfaces cleaved in situ to the XPS spectrometer vacuum, produced with a cryo pump, slowly changes them into lanthanide oxides and elemental antimony. The cleavage of LaSb in air also induced oxidation of the elemental antimony. The binding energies of Sb3/2,5/2 of elemental antimony produced in the vacuum were the same as those of bulk metal Sb. However, a chemical shift of the level of the elemental Sb in decomposition layers on the samples cleaved in air was positive for LaSb and negative for CeSb.
Chemical environment of Ba2+ in a series of chalconide and halide salts
Authors: Berrie C. L. , Langell M. A.
Published: May 2005

Barium Auger parameters correlate linearly with fractional ionic character, defined by simple electronegativity concepts. More fundamentally, the variation in Auger parameter is quantitatively associated with ligand polarization energy Ep, resulting from the interaction of the polarizable ligands with the barium core hole coulombic field. This paper demonstrates the Ba2+ Auger parameter correlations, and is complementary to work published previously in this journal (C. L. Berrie and M. A. Langell, Surf. Interface Anal. 17, 635 (1991)).
Preparation and characterization of organic superlattice thin films grown on hydrogenated silicon single‐crystal substrates
Authors: Ishitani A. , Nonaka T.
Published: May 2005

We have succeeded in preparing very thin (nanometre order) alternating layers that can be called ‘organic superlattices’ by using a special combination of materials, substrates and deposition conditions with good verification by various characterization techniques.

Specially surface‐treated single‐crystal silicon substrates with hydrogen‐terminated dangling bonds on the surface were used to induce van der Waals heteroepitaxial growth. Choice of materials with the appropriate molecular shapes and aggregation force is also important for preparing flat molecular films. Tetraphenylporphyrins (H2TPP and ZnTPP) and phthalocyanines were used for this purpose. A molecular beam epitaxy chamber with specially designed cells was used with the cooled substrates.

Direct proof of the alternating composition was given by transmission electron microscopy observation, avoiding decomposition by the electron beam, and also by SIMS depth profiling under special conditions to ensure good depth resolution. X‐ray diffraction in the small‐angle region gives the periodicity of the alternating layers, as well as their crystal quality. Atomic force microscopy confirms the atomic flatness and also gives the molecular orientation in the films. Fourier transform infrared spectroscopy examines the chemical stability of the compounds during deposition and also gives the axial orientation of the molecules in the films.
Interaction of oxygen with ZrN at room temperature: An XPS study
Authors: Prieto P. , Galán L. , Sanz J. M.
Published: May 2005

Quantitative XPS has been used to characterize the interaction of oxygen with ZrN at room temperature. The results indicate that ZrN remains unaffected for oxygen exposures <104 L at oxygen pressures <10−7 Torr. However, higher oxygen exposures at higher pressures cause the formation of an oxynitride (ZrN0.5O0.5) and ZrO2. At 108 L saturation is reached, with the formation of an oxidized layer that is 17 Å thick formed by 5 Å of ZrO2 and an interface layer (12 Å thick) of average composition ZrN0.5O0.5. Analysis of the core levels and valence band of the oxynitride demonstrates its ionic character as well as its insulating properties in comparison with metallic ZrN.
An in situ XPS study of the formation of nickel—polyethylene and nickel—polypropylene interfaces
Authors: Marcus P. , Meyer A. , Hinnen C.
Published: May 2005

The initial stages of formation of nickel–polyethylene and nickel–polypropylene interfaces have been investigated by X‐ray photoelectron spectroscopy (XPS). Nickel was sputter‐deposited on the polymer surfaces in the UHV chamber attached to the spectrometer, and the Ni 2p3/2 and C1s regions were analysed in situ as a function of deposition time, until the completion of a metallic overlayer of ∼30 Å. The examination of the measured XPS spectra shows that there is no additional signal in the C1s region which would be associated with the formation of a strong chemical bond with charge transfer, in contrast with previous findings for aluminium sputter‐deposited on the same polymers. Accordingly, the Ni 2p3/2 region does not show any additional signal, but it exhibits a marked shift in the binding energy for the small amounts of deposited nickel (0.7 eV for the shortest deposition time). This shift in binding energy decreases with increasing amount of deposited metal. This observation gives evidence of the presence of small clusters on the surface, which finally form a continuous metallic layer with a thickness of ∼8 Å.
Use of XAS and chemical probes to study the structural damage induced in oxide ceramics by bombardment with low‐energy ions
Authors: Caballero A. , Leinen D. , Espinós J. P. , Fernández A. , González‐Elipe A. R.
Published: May 2005

A preliminary study by x‐ray absorption spectroscopy (XAS) of the structural modifications induced in mixed oxides by low‐energy (1–5 keV) Ar+ bombardment is presented in this paper. The analysis of the extended x‐ray adsorption fine structure (EXAFS) and x‐ray adsorption near‐edge structure (XANES) spectra recorded for bombarded Al2TiO5 and BaTiO3 has shown the randomization of the atomic network and the formation of TiO2 in the outermost layers of these materials. On the other hand, SO2 is proposed as a probe molecule to asess semiquantitatively the extent of structural damage in the surface layers of bombarded oxides. The incorporation of sulphur into this zone has been proved by depth profiling with XPS and Ar+ ions of 0.5 keV. In BaTiO3 the incorporation of sulphur increases with the energy of the primary ions. This fact suggests that the concentration of defects increases with the energy of the Ar+ beam and that the most disordered surface layers are more reactive towards SO2. A similar effect is not observed with TiO2 and Al2TiO5 because in these materials, where a considerable reduction of titanium to Tin+ (n < 4) species is produced by the preferential removal of oxygen, an overlay of elemental sulphur is formed by the reaction of SO2 with these species. This overlay prevents the diffusion of SO2 and therefore the incorporation of sulphur into the damaged layer of those samples.
XPS/AFM study of thermally evaporated aluminium/polycarbonate interface
Authors: Massoro Claudia , Le Quoc Toan , Pireaux J. J.
Published: May 2005

The interfacial interaction between polycarbonate and in situ thermally evaporated aluminium has been studied by x‐ray photoemission spectroscopy.

Core‐level spectra indicate that aluminium reacts, in the initial reaction stage, with the carbonyl groups (CO). In a second step, the CO entities begin to be involved. These mechanisms lead to the formation of a AlOC complex, confirmed by the appearance of a new component at lower binding energy in the C 1s signal.

After about 1.7 Å of Al deposition a new C 1s component is also observed at lower binding energy and is attributed to the interaction between Al and the phenyl ring, which leads to a strong perturbation of the π electron system of the phenyl ring and then to an AlC bond. Analysis of the shake‐up satellites of metallized polycarbonate confirmed these interactions.

The morphology, as observed by atomic force microscopy measurements, of the Al on polycarbonate is also presented.
XPS study of passive films formed on an iron—aluminium intermetallic compound in acid solution
Authors: Frangini S. , Giorgi R. , Lascovich J. , Mignone A.
Published: May 2005

Surface films grown on the intermetallic B2‐FeAl alloy after wet‐mechanical polishing and after a wide range of anodic polarization conditions in 1N H2SO4 have been analysed by x‐ray photoelectron spectroscopy. The results clearly indicate a remarkable enrichment of aluminium within all the films regardless of the growth conditions. Analysis of the metal–oxygen bonds has made it possible to distinguish several oxidized species. It has been found that most of the iron hydroxides are concentrated on the film surfaces, whereas aluminium hydroxides appear more homogeneously distributed over the depth of the oxide films. The thickness of the film shows an abrupt increase at 1 V, accompanied by a marked increment of Al hydroxide species.
Surface analysis of patterned and selectively metallized silicon surfaces with imaging and static SIMS
Authors: Van Der Wel H. , Van Der Sluis‐Van Der Voort E. , Willard N. P.
Published: May 2005

The use of imaging and static secondary ion mass spectrometry is demonstrated for the chemical characterization of the top monomolecular layers of chemically modified and patterned silicon wafers. Surfaces with areas of different chemical compositions and reactivities (e.g. hydrophobic/hydrophilic) were created by chemical modification with a light‐sensitive organosilane, followed by UV irradiation or by chemical modification with 3‐aminopropyltriethoxysilane, followed by local removal of the silane through oxidation with UV ozone. The latter surfaces were also selectively metallized on the aminosilylated areas as an example of the applications possible for these patterned surfaces.

The chemical surface composition and structure of the organosilylated and selectively metallized silicon wafers are adequately characterized with static SIMS. The patterns created on the wafers are observed with good contrast in the SIMS images of the molecular ionic fragments and elemental ions characteristic for the particular surface compositions. The results can be used to improve the chemical modification reactions.
Application of factor analysis to the auger electron spectroscopy study of YBa2Cu3O7−x superconductors
Authors: Roose N. , Ye M. , Vereecken J. , Seibt E. W.
Published: May 2005

In this paper factor analysis applied on AES measurements is used in the study of the chemical composition of YBa2Cu3O7‐x superconductors.

In the first part, YBa2Cu3O7‐x thin films deposited on MgO and SrTiO3 are investigated by AES depth profiling. Factor analysis makes it possible to identify secondary phases present at the surface and the interfaces. This method also offers the possibility of determining the real interface thickness, as the edges of pure film and pure substrate are more accurately defined.

In the second part, the radiation induced effects of a 10 keV electron beam are investigated on YBa2Cu3O7‐x single crystals. Besides the stoichiometric changes the chemical changes in function of the radiation dose are studied. Factor analysis indicates clear peak changes throughout the irradiation process.
Interaction of copper(II) ions with pyrite and its influence on ethyl xanthate adsorption
Authors: Voigt S. , Szargan R. , Suoninen E.
Published: May 2005

X‐ray photoelectron spectroscopy (XPS) has been used to investigate the interaction of copper(II)‐containing aerated aqueous solution (pH 4–10) with pyrite (FeS2) surfaces and its influence on subsequent ethyl xanthate adsorption from solution. Evidence is provided that Cu(II) ions can be adsorbed independent of pH, changing their oxidation state to Cu(I). This is attributed to a new Cu–S surface species, In addition, Cu(II) can be stabilized as a complex hydroxy species on pyrite at pH ≥ 6. Time‐dependent adsorption studies were carried out to elucidate the influence of pH on the copper adsorption rate, considering also the different copper oxidation states. A fast saturation of the sulphide surface with Cu(I) is observed at pH 5, whereas the Cu(I) uptake starts only slowly at pH 8 and pH 10. Prolonged conditioning in alkaline solution results in a precipitation of Cu(II) hydroxy species. Simultaneously, the amount of adsorbed Cu(I) increases until the same Cu(I) level is reached as in acidic media. After subsequent immersion in ethyl xanthate solution of pH 6–9, both Cu(I) and Cu(II) ions adsorbed on pyrite are found to form Cu(I) ethyl xanthate in accordance with previously published infrared spectroscopic and microflotation results.
Simultaneous background subtraction and depth profile determination from AES/XPS measurements
Authors: Werner Wolfgang S. M. , Tilinin Igor S. , Beilschmidt Herbert , Hayek Markus
Published: May 2005

A general expression for the energy and angular distribution of Auger/photoelectrons emitted from a specimen with an arbitrary depth profile is presented. The central quantities in this expression are the so‐called partial escape distributions, which describe the probability that a signal electron generated in a certain depth interval escapes from the surface with a direction in a certain angular interval after experiencing a certain number of inelastic scattering processes. The partial escape distributions accounting for elastic scattering are calculated in the transport approximation. Comparison of analytical calculations with Monte Carlo data based on the more relastic Mott crosssection for elastic scattering yields excellent agreement. As an illustration of the general approach, the energy/angular spectrum of a sample with a model depth profile has been evaluated using analytical calculations and Monte Carlo data. The results obtained show that the proposed formalism properly accounts for elastic and inelastic processes and correctly predicts the shape of the energy distribution in the vicinity of the peak. It is, moreover, shown that the true intrinsic spectrum and depth profile may be reconstructed simultaneously from the measured energy/angular distribution of emitted electrons.