bluuebunny/crossref_metadata_2025_split huggingface dataset:
The improved MTCIP‐1A (modern thermodynamic calculation of interface properties—first approximation) and its application to the (Pt)Ni surfaces
Authors: Mezey L. Z. , Hofer W. 
Published: December 2004

AbstractThe MTCIP (modern thermodynamic calculation of interface properties) theory states the general condition of the thermodynamic equilibrium state (TES) for any kind of interface, any number of components and interface sublayers. In the MTCIP‐1A (first approximation) for a binary dilute solid mixture, the monolayer surface composition is calculated in the TES (allowing for a chemisorbed or segregated overlayer as well). This approach has been used successfully so far for bimetallic alloys and as well for the segregation of non‐metallic solutes on metal surfaces, and is further developed here. This new version is used for problematic PtNi surfaces, both low‐index and polycrystalline. All the parameters needed to follow the calculations are given. In all cases, the theory agrees with the experiments at last qualitatively, and in most cases even quantitatively, although the PtNi surfaces were the most problematic for theoretical calculations.
Thickness determination of surface oxides on metal powder by AES depth profiling
Authors: Norell M. , Nyborg L. , Tunberg T. , Olefjord I. 
Published: December 2004

AbstractA method for thickness determination of overlayers on irregularly shaped samples is established using AES depth profiling and stereophotogrammetry. The analysis is performed on a small selected area assumed to be flat. The angle of ion incidence on the area, given by the scalar product of the ion beam vector and the normal to the surface, is obtained by determining the normal using a sterological method based on rotation of a titled sample. The variation in etch rate with the angle of ion incidence is determined for various oxides on flat samples. Application studies show that the angle of ion incidence on gas‐atomized metal particles can be determined from their spherical shape; the variation in etch rate is found to agree well with that calibrated on flat surfaces. It is also demonstrated how the presented method can be used when determining the oxide thickness in different areas on highly irregular water‐atomized metal particles.
Evaluation of take‐off‐angle‐dependent XPS for determining the thickness of passivation layers on aluminium and silicon
Authors: Gunter P. L. J. , De Jong A. M. , Niemantsverdriet J. W. , Rheiter H. J. H. 
Published: December 2004

AbstractInvestigating the effect of a cleaner (used to remove lubrication oil residues) on the surface composition of rolled aluminium foils, we applied angle‐dependent XPS to determine the thickness of the passivation layer on these foils. We found the simple uniform overlayer model, which has frequently been applied to translate XPS intensity ratios into a value for the overlayer thickness, to be inapplicable on these aluminium foils. However, data obtained from an Si(100) single‐crystal surface were in rather good agreement with the model. SEM images from the aluminium foils show that their surface is rough on the (sub)micron scale. We believe this roughness to be the reason for the inapplicability of the uniform overlayer model. Simulations of XPS intensity ratios for model rough surfaces support this point of view. Both experiment and simulations make it clear that one should not base XPS thickness determinations on one measurement only, because in that case the applicability of the uniform overlayer model cannot be checked.
Ultrafast electron dynamics at semiconductor surfaces and interfaces studied with subpicosecond laser photoemission
Authors: Haight R. , Baeumler M. , Silberman J. A. , Kirchner P. D. 
Published: December 2004

AbstractThe technique of subpicosecond angle‐resolved laser photoemission spectroscopy is described. Investigations of the dynamics of electrons excited into normally unoccupied states at the cleaved GaAs (110) 1 × 1 and Ge (111) 2 × 1 surfaces are detailed. In addition, we discuss experiments carried out on heterostructures formed by the growth of Ge on the cleaved GaAs (110) surface as well as the molecular beam epitaxy (MBE) surface of GaAs (100) and (111).
Al‐Cu‐Si/TiW interface reaction due to thermal treatments
Authors: Misawa Y. , Koike Y. 
Published: December 2004

AbstractThe Al‐0.5 wt.% Cu‐1 wt.% Si/TiW interface reaction due to thermal treatments in nitrogen was investigated using SIMS, x‐ray diffraction (XRD), TEM, XPS and SEM. Titanium starts to diffuse into the Al alloy layer at low temperatures such as 350°C. However, Ti has hardly any effect on the sheet resistance. Tungsten diffuses and reacts with Al above 450°C. The rugged interfacial reaction product formed after annealing at 450°C, which may be W(Al, Si)2, does not affect the sheet resistance. The needle‐shaped reaction product formed after annealing above 500°C, which is Al12 W, is responsible for the large increase in sheet resistance. An aluminium oxide layer, several nanometres thick, formed on the Al alloy surface after annealing at 500°C acts as a W diffusion barrier.
Dependence of boron axial channelling in silicon on crystal orientation
Authors: Tian C. , Gara S. , Hobler G. , Stingeder G. 
Published: December 2004

AbstractThe axial channelling behavior of boron implants in 〈100〉, 〈110〉 and 〈111〉 silicon wafers is investigated by secondary ion mass spectrometry. The conventional electronic stopping models are tested by comparing with experimental results. The dependence of the channelling effects on these three major low‐index directions are revealed. A three‐parameter model is presented to describe channelling of boron in silicon. The results give a deeper insight into the channelling phenomena and provide the necessary information to study an electronic energy‐loss model for boron channelling in a silicon target.
XPS studies of oxide layers on InP after oxidation in the presence of Ce4+
Authors: Debiemme‐Chouvy C. , Ballutaud D. , Sculfort J. L. , Etcheberry A. 
Published: December 2004

AbstractQuantitative XPS analyses are carried out to study the III‐V semiconductor/solution interface. In the presence of ceric ions (Ce4+) solvated in sulphuric acid (H2SO4, 0.5–2 M), III‐V compounds undergo a dissolution which is completely governed by an electrochemical process. Competition between a superficial oxide growth and its quasisimultaneous dissolution determines the behaviour of the interface as a function of time. On InP some typical surface evolutions are observed, such as a decrease in the hole injection current during the reduction of cerium oxidized species. In order to explain this blocking effect, we have analysed the chemical composition of InP surfaces by XPS after oxidation in the presence of cerium ions. We report here the evolution of the oxide layer formed at the semiconductor/electrolyte interface in relation to the dipping time of the electrode and the cerium and sulphuric acid concentrations. It is observed that the lower the pH, the more soluble is the oxide layer. Moreover, increases in the cerium concentration and dipping time enhance the growth of a complex oxide layer. This layer is rich in oxidized phosphorus and strongly depleted in indium. Profiling of the layer shows a cerium distribution all over the oxide layer. The electrochemical behaviour of InP samples changes in relation to the properties of this complex multiphase film.
Weathering of wood and protection by chromium studied by XPS
Authors: De Lange P. J. , De Kreek A. K. , Van Linden A. , Coenjaarts N. J. 
Published: December 2004

AbstractIn order to understand better the protection mechanism of aqueous CrO3, the surface of untreated and treated wood, before and after weathering, was studied by XPS. For comparison, the reaction of CrO3 with filter paper, used as a model compound for cellulose, and with lignin powder was studied as well.Owing to differences in the O/C ratio and the shape of the C 1s signal, cellulose and lignin can be distinguished from each other with the aid of XPS. The low O/C ratio and the high C1 (CC, CH) contribution found for the surface of wood show that the upper layer is enriched with ligin and extractives. Weathering of wood starts with the degradation of lignin, and the appearance of cellulose on the surface increases the O/C ratio and shifts the maximum of the C 1s signal to the C2 (COC, COH) position.Aqueous CrO3 oxidizes lignin powder and possibly also cellulose. The effect on wood, as observed with XPS, is small. The protection, however, is very clear; the increase of the O/C ratio of CrO3‐treated wood during weathering is much slower than the increase for untreated wood. After weathering, the C 1s signal still resembles the C 1s signal of lignin, so the CrO3 protects the lignin from degradation.
Oxidation of Gd thin films on Si substrates via grain boundaries
Authors: Molnár G. , Petö G. , Kótai E. , Zsoldos E. , Gyulai J. , Guczi L. 
Published: December 2004

AbstractThe low‐temperature oxidation of Gd thin films evaporated on Si substrates and the role of Si native oxide at the interface of Gd silicide growth have been investigated by x‐ray diffraction, XPS and RBS. The Gd layer is extremely reactive towards oxygen and is quickly oxidized in air. Its reactivity can be diminished by introducing a small quantity of Si into the Gd film. In the initial stage Si is accumulated mainly at the grain boundaries of the Gd film, thereby blocking the main oxygen diffusion path and preventing Gd2O3 formation. If Si native oxide is initially present, at low temperature the growth of Gd silicide is slowed down but at high temperature Si/SiO2/Gd is easily transformed to Gd2O3.
Extended energy loss fine structure and x‐ray photoelectron spectroscopy studies of clean and oxidized Fe thin films on polycrystalline Cu
Authors: Di Nardo S. , Lozzi L. , Passacantando M. , Picozzi P. , Santucci S. , De Crescenzi M. , Den Daas H. 
Published: December 2004

AbstractThe electronic and structural properties of very thin iron films deposited in ultrahigh vacuum on polycrstalline copper have been studied by x‐ray photoemission and Auger spectroscopies and the extended energy loss fine structure technique beyond the L2, 3 edges of iron. Shifts in both core level and valence band binding energies together with a decrease in nearest‐neighbour distance are consistent with a cluster growth picture. Successive oxidation and thermal treatments have shown a selectivity towards oxidation of the iron deposits with respect to the copper substrate and a restoration of the cleanness of the iron deposit after thermal treatment.
Tougaard background deconvolution study of the deposition of Langmuir–Blodgett films of long‐chain hydrocarbon amines with titanyl oxalate ions
Authors: Sastry Murali 
Published: December 2004

AbstractMultilayers of a titanyl oxalate complex with n‐octadecylamine were picked up onto quartz substrates by the Langmuir–Blodgett technique. X‐ray photoemission was used to detect the various species in the film and their relative concentrations. A Tougaard background deconvolution analysis of the photoelectron spectra was performed using the differential inelastic scattering cross‐section determined from reflection electron energy‐loss spectroscopy. By contrast with previous work on layer‐structured arachidate films, this analysis indicated that the various elements in the film were present with homogenous depth distributions. This is consistent with XPS take‐off angle studies and with x‐ray diffraction and electron microscopy studies, which showed the film to be amorphous. The composition of the film was determined to be TiO6.7C49N1.7, in reasonable agreement with the expected composition of TiO9C40N2.
XPS and ISS study of NiTiO3 and PbTiO3 subjected to low‐energy ion bombardment. I. Influence of the type of ion (Ar+ and O)
Authors: Leinen D. , Fernández A. , Espinós J. P. , González‐Elipe A. R. 
Published: December 2004

AbstractCompositional and chemical changes in PbTiO3 and NiTiO3 induced by 3.5 keV Ar+ and O2+ ion bombardment have been studied quantitatively by XPS and ISS. Whereas in NiTiO3 the Ti/Ni ratio determined by XPS remained practically constant, a preferential loss of lead was observed in PbTiO3 during ion bombardment. In that case, Ar+ removed lead more effectively than O2+ ions. Argon ion bombardment induced strong chemical changes in both titanates: Ni2+ and Pb2+ species were nearly totally reduced to the metallic state, while Ti4+ species were partially reduced to Ti3+ and Ti2+ oxidation states. This reduction is more efficient in PbTiO3 than in NiTiO3. The preferential loss of lead in PbTiO3 and the removal at equivalent rates of Ti and Ni in NiTiO3 are discussed within the context of the chemical stability and physical constants of the compounds by assuming a chemically guided lattice relaxation of the bombarded targets. The possibility that solid‐state reactions play a role in the control of some of the results is stressed. Other possible effects, such as agglomeration or surface enrichment, are discussed by using the ISS results.
Application of the artificial neural network approach to the recognition of specific patterns in Auger electron spectroscopy
Authors: Souza M. N. , Gatts C. , Figueira M. A. 
Published: December 2004

AbstractThe artificial neural network (ANN) approach was applied to the identification of Auger electron spectral patterns. The ANN structure employed was the counter‐propagation architecture with an unsupervised learning algorithm. For training such a network, it is only necessary to provide a data set with samples of the patterns to be recognized, and the network itself will extract the relevant statistical information to organize similar patterns into specific classes. We used a training data set of five different Auger spectra (Fe, Au, Si, Sn, Cu) to which a random fluctuation of up to 5% of the highest peak was added. To the test set, however, the added fluctuation was up to 50% and we observed that the network was able to identify precisely and test spectrum after only a few training sessions. The ANN synapses can be interpreted as the average spectra of the training set for each specific class, tending to zero fluctuation spectra as the number of training samples becomes large. The results obtained show that even by using an extremely simple ANN structure the classification of single‐element Auger spectra was made easy also in the case of extremely noisy spectra.
X‐ray photoelectron diffraction studies of the surface chemistry of non‐stoichiometric synthetic spinel
Authors: Ash Lynne A. , Evans Stephen 
Published: December 2004

AbstractAngle‐resolved XPS data from a synthetic spinel crystal of approximate composition MgO·(3.4)Al2O3 are reported and discussed. Strong x‐ray photoelectron diffraction (XPD) effects were observed both in argon ion bombarded/annealed surfaces (which were grossly magnesium‐deficient) and in chemically etched surfaces prepared by treatment with sodium peroxide at 480°C followed by an acid wash. Many major features of the XPD patterns could be explained using the enhanced forward scattering concept. The relative magnitudes of the XPD modulation of the photoelectron intensity suggest that no more than one‐third of the aluminium occupies tetrahedral sites, in accordance with magic‐angle‐spinning nuclear magnetic resonance experiments, and confirm that the magnesium, in contrast, remains predominantly in the tetrahedral sites. Thin layers of magnesium, cobalt(II) and chromium(III) oxides deposited on the crystal surface from nitrate precursors diffused rapidly into the crystal at ∼1100°C, with first‐order kinetics, but the mixed‐oxide surfaces so created showed no evidence of order.
Auger Si LVV, O KLL and N KLL lineshapes at air‐exposed silicon nitride surfaces: Pattern recognition analysis
Authors: Zemek J. , Vystrcil T. , Lesiak‐Orlowska B. , Jablonski A. , Luches A. 
Published: December 2004

AbstractAuger electron spectroscopy measurements have been performed on silicon nitride layers exposed to air. The layers were deposited on Si(100) wafers kept at 300°C or 600°C by excimer laser ablation of a silicon target under various ammonia pressures. The Si LVV, O KLL and N KLL lineshapes of silicon nitride layers and of in situ prepared clean surfaces of standards are compared by applying pattern recognition (PR) methods to obtain bonding information of elements within the analysed volume. The PR results based on Auger Si LVV, O KLL and N KLL spectra compare very well. They are also in agreement with the results of XPS. The chemical states of silicon atoms in all silicon nitride layers depend strongly on the deposition conditions used. For low ammonia pressures, surface regions of silicon nitride layers show a twofold coordination with oxygen to silicon atoms (SiO2), whereas for higher ammonia pressures there is a four fold coordination of silicon to nitrogen atoms (Si3N4). The results are interpreted as follows. The silicon‐rich silicon nitride layers are formed at the lower ammonia pressure where the silicon oxide dominates over silicon nitride in the surface region, whereas for the higher ammonia pressure silicon nitride is prevalent. A new approach of the PR method, so‐called ‘cluster analysis’, shows a close similarity in the chemical states of nitrogen atoms in the nitride layer formed at higher pressure and silicon nitride standard, indicating a threefold coordination of nitrogen to silicon atoms. Subtle differences revealed in the spectral shapes elucidate the strongly correlated behavior of the N KLL lineshapes with the deposition conditions used.
Quantitative analysis of metal alloys based on the total X‐ray photoelectron spectra
Authors: Ławniczak‐Jabłońska K. 
Published: December 2004

AbstractThe method for quantitative XPS analysis proposed by Wertheim was used in the present work to check the composition of Ni–Mo alloys. These alloys had already been studied by the usual analysis based on the main line intensities. Both methods provided practically the same results. The sensitivity factor in these alloys is not constant, owing to changes of the crystal structure in the studied composition range. The total signal analysis offered a very quick method to estimate the alloy composition from only the wide spectrum measurement but it does not eliminate the problem of sensitivity factors, at least in the case of mixed‐phase alloys. This method is not influenced by satellites but still is sensitive to the changes of surface composition induced by sputtering.
Energy calibration of x‐ray photoelectron spectrometers: Results of an interlaboratory comparison to evaluate a proposed calibration procedure
Authors: Powell C. J. 
Published: December 2004

AbstractResults are reported of an interlaboratory comparison conducted to evaluate a proposed procedure for calibration of the binding energy (BE) scales on x‐ray photoelectron spectrometers. The calibration was performed at two points on the BE scale (the Au 4f7/2 and Cu 2p3/2 lines) and checks were made of the assumption of BE‐scale linearity from measurements on other lines. It is shown here that small offsets (up to ∼0.05 eV) can arise if peaks are located with assumed backgrounds of non‐zero slope or if multipeak fits are made to Cu L3VV and Ag M4VV Auger spectra. The two parameters in the linear calibration equation could vary with analyzer pass energy and choice of x‐ray source on a particular instrument. Check measurements of the calibrations were performed with the Ag 3d5/2 photoelectron line and the Cu L3VV and Ag M4VV Auger lines; difference between the corrected positions of these lines and the corresponding reference data were satisfactorily small in most cases. For Auger lines excited by monochromatized aluminum x‐rays, however, the differences were significant and were interpreted in terms of different average x‐ray energies for the monochromated and unmonochromated x‐ray sources. The interlaboratory comparison was useful in testing the proposed calibration procedure and in providing guidance for some improvements.
Surface characterization of novel plasma‐polymerized primers for rubber‐to‐metal bonding
Authors: Tsai Y. M. , Boerio F. J. , van Ooij W. J. , Kim Dong K. , Rau Thomas 
Published: December 2004

AbstractThin (750 Å) plasma‐polymerized films of acetylene were deposited onto polished steel substrates in an inductively coupled r.f. reactor. The films were characterized by x‐ray photoelectron spectroscopy (XPS), Fourier‐transform infrared spectroscopy (FTIR), Auger electron spectroscopy (AES) and secondary ion mass spectrometry (SIMS) immediately after deposition and after aging in the atmosphere. The FTIR spectra of the as‐deposited films were characterized by bands related to mono‐ and disubstituted acetylene groups and by bands related to methyl and methylene groups. During exposure to the atmosphere, bands related to acetylenic groups decreased in intensity while new bands due to carbonyl groups appeared. When XPS spectra were obtained from films that were exposed to the atmosphere, new components assigned to oxidation products were observed in the C 1s spectra that were not observed for as‐deposited films, verifying that oxidation had occurred. Numerous peaks related to aromatic structures were observed in positive SIMS spectra of as‐deposited films. Results obtained from AES showed that the plasma‐polymerized films were continuous and that the oxide on the substrate surface was partially reduced during deposition.Plasma‐polymerized acetylene films were excellent primers for rubber‐to‐steel bonding. Miniature lap joints were prepared by using rubber as an ‘adhesive’ to bond together pairs of polished steel adherends primed with plasma‐polymerized acetylene films. The force required to break the as‐prepared joints was ∼2000 N for a bonded area of 64 mm2 and failure was 100% cohesive in the rubber. Similar results were obtained for joints prepared using polished brass substrates.Because of the complexity of reactions between rubber and the plasma‐polymerized primer, a model ‘rubber’ consisting of a mixture of squalene, zinc oxide, carbon black, sulfur, stearic acid, cobalt naphthenate, N,N‐dicyclohexylbenzothiazole sulfenamide and diaryl‐p‐diphenyleneamine was used to simulate the cross‐linking reaction. The results obtained using XPS, SIMS, AES and FTIR showed that sulfur diffused through the primer to form a layer of sulfide at the primer/substrate interface. Zinc and cobalt sulfides and perthiomercaptides, which formed at the interface between squalene and the plasma‐polymerized acetylene primer, catalyzed the reaction between squalene and the primer. Cross‐links between squalene and the primer were mostly mono‐sulfidic, although some evidence for di‐ and trisulfidic cross‐links was observed.
Effect of elastic scattering and cylindrical mirror analyser geometry on the evaluation of escape depths of auger electrons
Authors: Ding Z.‐J. , Shimizu R. 
Published: December 2004

AbstractWe have studied the effect of elastic scattering and analyser geometry on calculations of electron escape depths. A theoretical analysis of the electron escape depth has been presented that shows how it is related to the solid angle for detection and the geometrical configuration of a cylindrical mirror analyser. To estimate the extent to which elastic scattering can modify the values of the escape depth, Monte Carlo simulations of the emission of Auger electrons were carried out for Cu MVV (59 eV), Cu LMM (916 eV), Au NVV (238 eV) and Au MNN (2025 eV) signals. From the calculated depth distributions of signal electrons, we have derived a correction factor for the electron escape depth in terms of the corresponding inelastic mean free path which includes both the effects of elastic scattering and analyser geometry. We have found that elastic scattering reduces the value of the escape depth by several tens of per cent and, depending on the target, signal electron energy and analyser geometry, the ration between the escape depth and the inelastic mean free path varies from 0.4 to 0.6.