bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of surface stoichiometry in polycrystalline alloys by a crystallographic electron attenuation model: Application to the Ce/Rh system
Authors: Andersen J. E. T. , Warren J. P. , Zhang X. , Lambert R. M.
Published: May 2005

In order to obtain quantitative surface compositional information, an earlier crystallographic electron attenuation model has been extended to treat polycrystalline alloys. Simple correction factors are obtained that yield large corrections to elemental Auger intensity ratios. The model has been applied to a binary surface alloy formed by heating cerium overlayers on a polycrystalline rhodium substrate. It is shown that an alloy film is formed whose thickness is proportional to the number of Ce layers initially deposited. The surface alloy is identified as Ce3Rh2, which corresponds to a known bulk phase.
Influence of the surface chemistry on the wettability of stainless steel
Authors: Mantel M. , Wightman J. P.
Published: May 2005

Degreasing with solvents, chemical etching, polishing, oxygen and argon plasma treatment and heating and drying produce stainless‐steel surfaces with different amounts of organic contamination and ‘bonded water’. The hydroxide/oxide layer of the passive film formed on stainless‐steel foils is also affected by surface pretreatment. Electron spectroscopy for chemical analysis (ESCA) has been used to analyze the composition of the surface film formed after different cleaning procedures. Organic contamination on 304 stainless‐steel foils can be reduced by a factor of five using various cleaning treatments. Wettability or surface energy measurements have been performed on the treated surfaces and it was found that the surface energy of the metal decays with the inverse of the contamination layer thickness. As these cleaning treatments lead to different oxide layers, it is concluded that the nature of the oxide layer is not the main parameter that determines the surface free energy of metals.
Calculations of a CHA transmission function for quantitative analysis in the constant pass energy mode. I. Point sources for AES
Authors: Kato M. , Sekine T.
Published: May 2005

The analyser transmission function T of a concentric hemispherical analyser (CHA) with an input lens system has been studied, and the behaviour of T under suitable operation conditions for a point source has been determined by means of numerical calculations. One of the significant factors controlling T was found to be the aberrations of the input lens, which have a strong dependence on the retardation ration γ and the angular magnification Mα of the lens. The Mα also determines the entering angles of electrons to the CHA, and thus this should be kept sufficiently small as far as the aberrations in the CHA are concerned. The calculated results showed, however, that for each γ there exists an optimum Mα, which corresponds to a compromise point between the aberrations of the input lens and those of the CHA. If Mα is kept constant, T varies according to the increase or decrease in the lens aberrations as functions of γ. Lineshapes calculated for a monochromatic point source were also shown. These were found to be asymmetrical and have tailings on the low‐energy side due to the aberrations of the CHA.
Incorporation of elastic scattering into composition–depth profile reconstruction from angle‐resolved Auger/XPS data
Authors: Dwyer V. M.
Published: May 2005

Neglecting elastic scattering in the inversion process for reconstructing composition–depth profiles from angle‐resolved Auger/XPS spectra leads to several effects that are likely to be misinterpreted. For example, there appears to be an erroneous diffusion of the substrate material to the surface in the case of a simple overlayer. In addition, the thickness of the overlayer is likely to be overestimated by typically ∼20% for Auger/XPS energies.
Inhomogeneous charge effect on a natural mineral studied by XPS
Authors: Rueda F. , Mendialdua J. , Rodríguez A. , Casanova R. , Barbaux Y. , Gengembre L. , Jalowiecki L. , Bouqueniaux D.
Published: May 2005

We report on XPS results that show an inhomogeneous charge effect, greater than 1.0 eV and far greater than the accuracy of the measurements (∼0.2 eV), exhibited by a natural mineral essentially composed of SiO2 and Fe2O3. This mineral has proved to be an efficient catalyst in a Fischer–Tropsch reaction. We have corrected this differential charge effect by using two internal references in order to interpret satisfactorily our XPS data.
Oxidation study of 3d transition metals (Cr, Fe, Co and Ni) and rare earth (Tb): Application to auger depth profiling of magneto‐optical disk
Authors: Abe Y. , Kato A. , Nakamura T.
Published: May 2005

Through the oxygen exposure experiments on 3d transition metals (Cr, Fe, Co and Ni) and rare earth (Tb), we studied the initial oxidation by means of Auger peak‐to‐peak height (APPH) method. Based on the results obtained, a simple technique using the ratio of APPH was applied to the Auger depth profile analysis of magneto‐optical disk (MOD). It was clearly indicated that the preferential oxidation of Tb occurred only at the lower interface between the TbFeCo and metal‐oxide layers, and this technique can be used to obtain the chemical information about the interface oxidation in Auger depth profiling.
Ion beam analyses of ceramics and glasses in nuclear energy
Authors: Matzke Hj.
Published: May 2005

Ion beam techniques (Rutherford backscattering (RBS) with and without the channeling effect technique, resonance scattering on 16O with high energy He‐beams, elastic recoil detection analysis (ERDA), SIMS and nuclear reactions such as H(15N, αγ)12C for H detection, etc.) have been used extensively and successfully in the past years to investigate surfaces and surface‐near layers of materials of importance for nuclear energy. These materials include the nuclear fuels UO2 and UN, the tailor‐made borosilicate glasses and the special ceramics (e.g. SYNROC) for solidification and safe long‐term storage of high level radioactive waste. In this latter area, ion beam techniques have significantly improved the understanding of the mechanisms and kinetics of corrosion in water. Ion beam techniques have also been applied to introduce foreign atoms and to modify the surfaces of these materials, and additional ion beam techniques were subsequently used to analyse the surface changes and modifications. This article presents a review of these largely unpublished activities and points out some of the important progress achieved recently, e.g. on the mechanism of polygonization of UO2.
Interfacial effects of a multifunctional additive on carbon black filled rubber
Authors: Sheng E. , Bradley R. H. , Sutherland I. , Freakley P. K. , Ismail H.
Published: May 2005

Interfacial effects of a multifunctional additive (MFA), i.e. n‐tallow‐1,3‐propanediamine salt of a carboxylic acid, on carbon black filled rubber have been studied. Surfaces of several normal cure rate carbon blacks were characterized by XPS and vapour‐phase chemical derivatization, and the carbon blacks were found to have very few functional groups on their surfaces. The MFA has been found to decompose at ∼120 °C and the decomposition generates a diamine and a carboxylic acid. Bound rubber, determined by o‐xylene extraction, was found to decrease with the addition of MFA and a limiting bound rubber value was obtained at the MFA loading which corresponds to a monolayer coverage of the carbon black. The reduction of bound rubber with the addition of MFA is attributed to the release of the occluded rubber within carbon black agglomerates as a result of improved dispersion induced by the MFA. Mechanical properties were found to improve with the addition of MFA and the improvement was again attributed to the dispersing effect of MFA. Optimum mechanical properties were again observed to occur at an MFA loading which approximately corresponds to a monolayer coverage of the carbon black surface.
Optical and electronic properties of Ag‐ and Cu‐TCNQ in polymeric matrix
Authors: Arena A. , Di Marco G. , Giorgi R. , Mezzasalma A. M. , Patanè S. , Saitta G.
Published: May 2005

The optical and electronic properties of the Cu‐ and Ag‐TCNQ salts determined by means of conventional spectrophotometry, reflection electron energy loss spectroscopy (REELS), and x‐ray photoelectron spectroscopy (XPS) measurements, are compared with those obtained for the copper and the silver TCNQ salts dissolved into a polyethyleneimine matrix. The optical properties of the obtained complexes differ substantially from those of the starting compounds, in particular, because of the interaction between the CuTCNQ and the polyethyleneimine, the state of oxidation of copper changes from Cu+1 to Cu+2. No meaningful changes are observed in the shape and peak position of the Ag 3d peaks of the silver‐based samples.
ARXPS and LEISS characterizations for chemically etched and ion‐bombarded GaAs(100) surfaces
Authors: Sullivan J. L. , Yu W. , Saied S. O.
Published: May 2005

The effects of chemical etching and noble gas ion bombardment on GaAs(100) surfaces were investigated by angular resolved x‐ray photoelectron spectroscopy (ARXPS) and low energy ion scattering spectroscopy (LEISS). The results show that at the As received GaAs surface, Ga oxide is the major component, resulting in a Ga concentration slightly higher than As. Chemical cleaning by hydrochloride acid (HCl(conc.) to H2O1:1) followed by solvent washing efficiently removed the oxide layer, but ARXPS showed a strong As enrichment occurs at the cleaned GaAs surface. Ion bombardment was carried out using 3 keV Ar ions with a beam current of 1 mA for 50 min. XPS results show that at steady state the ion‐bombarded GaAs surface is depleted in As (As/Ga ∼ 0.8), but ARXPS indicates an As increase at the very surface. This is further confirmed by Ne+ LEISS analysis, which shows the top layer As concentration is increased by 40% after ion bombardment. The results indicate that bombardment‐induced compositional changes are due to Gibbsian segregation.
Irradiation effects induced by reactive and non‐reactive low energy ion irradiation of graphite: An electron spectroscopy study
Authors: Gouzman I. , Brener R. , Cytermann C. , Hoffman A.
Published: May 2005

The effect of low energy Ar+ and N2+ irradiation of highly oriented pyrolytic graphite (HOPG) has been investigated by AES and XPS. Based on measurements of the C(KVV) Auger line shape before and after irradiation it has been found that a high degree of structural disorder is induced in the near‐surface region of HOPG. The production of defects induced by the irradiation process was established by the appearance of a shoulder at the high energy side of the C(KVV) Auger line. After Ar+ irradiation the shoulder is well defined and clearly visible in the Auger spectrum. However, after N2+ irradiation this shoulder is broader and its intensity is smaller than that observed after Ar+ irradiation. It is suggested that the defects created during the N2+ irradiation process are partly compensated by chemical bonding between implanted nitrogen and displaced carbon atoms. XPS measurements confirmed the existence of chemical bonds formed between the implanted nitrogen and carbon atoms.

The effect of thermal annealing of the irradiated graphite was investigated up to 500 °C. At temperatures as low as 100 °C a decrease of the shoulder intensity was observed, whereas the desorption of the implanted Ar occurs at 300–400 °C only. These results suggest that the defects created by Ar+ irradiation are partially annealed. For N2+ irradiation, some nitrogen desorption occurs accompanied by a broadening and splitting of the N(1s) core‐level line. Also in this case, the shoulder intensity decreases with increasing the annealing temperature. It is suggested that partial annealing of the nitrogen‐implanted layer takes place. These results are of relevance for the understanding of the basic processes occuring during deposition of carbon nitride thin films by ion beam‐assisted methods.
Surface concentration modification of PtPd alloys by noble gas ion sputtering
Authors: du Plessis Johan , Taglauer Edmund
Published: May 2005

The surface concentration of three PtxPd1 − x alloys (x = 0.3, 0.5 and 0.7) under ion bombardment was studied as a function of ion species and ion bombardment energy for the noble gas ions He, Ne, Ar and Xe in the 0.5–1.25 keV energy range. The surface composition was measured by low‐energy ion scattering spectroscopy (ISS) and Auger electron spectroscopy (AES). It was observed that Pd is preferentially sputtered from the surface of these alloys (as corroborated by previous studies). This effect was found to be greatest for the lightest ion (He) and most pronounced for the lowest energies used. Only a very weak dependence of the surface concentration on the energy of the heaviest ion (Xe) was detected. Comparing ISS and AES (true surface and near‐surface information respectively), it was also found that Pd is depleted in the near‐surface region. The depletion is ascribed to radiation‐enhanced diffusion and segregation and it is shown how the overlaid contour mapping of ISS and AES intensities, as a function of diffusion coefficient D and segregation energy ΔG, may be used to determine the radiation‐induced diffusion coefficient D as a function of ion species and ion energy.
Recent aspects of surface infrared spectroscopy
Authors: Dumas Paul
Published: May 2005

Among the various classes of techniques used to probe solid surfaces, surface infrared spectroscopy has gained wide recognition for its ability to determine the chemical nature of surfaces and interfaces.

Synchrotron infrared radiation has been demonstrated to be a source of high brightness in the far‐IR region, allowing determination of adsorbate‐substrate modes as well as frustrated vibrational modes of adsorbed molecules.

Sum frequency generation, which uses both IR and visible pulses generated by lasers, and coupled at surfaces, allows the identification of species strictly located at the interface.

Kinetic as well as dynamics measurements are a growing area of time‐resolved spectroscopy, using either spectrometers or lasers.
Surface acoustic wave resonance spectroscopy (SAWRS) as a novel technique to study surface phenomena
Authors: Boronin A. I. , Kvon R. I. , Prosvirin I. P. , Brezhnev V. N. , Ostanin V. P. , Seriklaev I. E. , Tupikov V. S. , Belyaev A. N.
Published: May 2005

A new method is proposed for investigating surface phenomena based on the observation of the acoustic vibration modes of surface structures at high resolution. Experimental SAWR spectra can be obtained under a narrow frequency band excitation (Δω/ω ∼ 10−5) in a wide range (100 kHz–10 MHz). Application of this method to Ag(111) and Pt(100) single crystals reveals the existence of very narrow resonant acoustic vibration modes with Δω/ω ∼ 10−3–10−4 demonstrating strong anomalies in the phonon energy distribution function of solids. The behaviour of these anomalous peaks is very sensitive to surface structure and to the presence of adsorbates.
Extended fine structure in the secondary electron emission spectra of graphite and glassy carbon
Authors: Hoffman A. , Brener R. , Cytermann C.
Published: May 2005

The electron excited secondary electron emission (SEE) spectra of highly oriented pyrolytic graphite (HOPG) and glassy carbon (GC) were measured in the 0–150 eV electron kinetic energy range.

For HOPG, the SEE spectrum was measured as a function of primary electron beam energy above and below the threshold for carbon core level 1s ionization. The SEE spectrum in the 0–70 eV range reflects high energy conduction band states, in agreement with band structure calculations and other spectroscopic techniques sensitive to the empty density of states. For electron kinetic energies above ∼ 70 eV the spectrum of HOPG displays a well defined structure which has not been studied previously. We found that the SEE fine structure in the low energy range up to ∼ 40 eV shows some dependence on primary electron energy, whereas for larger energies a much weaker dependence was found. It has been established that the SEE spectrum is strongly affected by low‐energy Ar ion irradiation of the HOPG surface. This result suggests that the SEE spectrum is very sensitive to crystal defects induced by the irradiation process. The lower‐energy range of the spectrum, up to ∼ 40 eV was found to be more sensitive to damage induced by the ion irradiation process than the higher range of the spectrum.

For GC, the SEE spectrum in the 0–50 eV range is smeared out compared to that of HOPG. However, in the higher electron kinetic range some of the peaks measured for HOPG were also observed for GC. These results suggest that the lower‐energy range of the SEE spectrum is more sensitive to long‐range order, whereas the higher‐energy range of the spectrum reflects a shorter‐range order. It is suggested that SEE spectroscopy can be used as a very sensitive tool for the characterization of different carbon structures.
Local electronic structures in phosphorus oxyanions
Authors: Kövér L. , Némethy A. , Cserny I. , Nisawa A. , Ito Y. , Adachi H.
Published: May 2005

The local electronic structure around the core‐ionized phosphorus and oxygen atoms in solid phase Na3PO4, (NaPO3)n and Li3PO4 compounds has been studied by XPS and x‐ray excited Auger spectroscopy. Core level and valence band photoelectron spectra, as well as the O KLL Auger spectra have been measured using monochromated Al Kα excitation, while the high energy P KLV spectra have been excited using Mo‐x‐rays.

From the similarity of the structures of the P KLV spectra it can be seen that the effect of the common tetrahedral symmetry is dominant while the effect due to the change of the cation is much smaller. This observation is supported by comparing the respective valence band photoelectron spectra to each other, and to the results obtained from cluster MO calculations.

From the evaluation of the O KVV and O 1s spectra the oxygen Auger parameters have been derived and the 2p2p and 2s2p hole repulsion energies have been determined for each compound. The experimental values of the different Auger parameter shifts (Δα′, Δβ′) place the three oxyanions into the class of oxides, hydroxides and metallic anions instead of the class of non‐metallic anions and indicates the low electronic polarizability (similar to that of SiO2) of these phosphorus oxyanions.
The use of the anaerobic transfer electrochemical cell in the XPS investigation of polyaniline
Authors: Morea Gemma , Vickerman John C. , Walton John
Published: May 2005

Ananaerobic transfer electrochemical cell, mounted on a side arm of the UHV chamber at 90° to the fast entry lock system of the XPS instrument was used to study the base‐salt transitions in the three main forms of PANI (leucoemeraldine, emeraldine and pernigraniline). The curve analyses of the N 1s peak, cross‐checked with relative atomic ratios of different species, are used to gain an understanding of the surface chemistry of the various PANI forms. Parallel analyses, using an ex situ cell, are performed. The results obtained highlight the air sensitivity of base leucoemeraldine and confirm the possibility of obtaining, using an ATE cell, electrochemical surfaces which, when analysed by XPS, display the surface chemical composition they are expected to have in the cell. Nevertheless this approach is not free from experimental difficulties especially as far as designing and mounting of the sample/electrode is concerned.
Weight function for linear least squares fit of binary CuNi and PtPd alloy Auger spectra
Authors: Roos W. D. , van Wyk G. N. , Du Plessis J.
Published: May 2005

Linear least squares fits of an Auger spectrum of an alloy AB by a linear combination of elemental spectra A and B are usually performed without any weighting function Wi(E) as a function of the energy E. Too much significance is therefore attached to the constant (or peakless) segments of the spectrum. It is shown in this paper that the difference spectrum, i.e. (A — B) provides a suitable weight function for this type of fitting procedure. Two examples (CuNi and PtPd) are given where large overlaps occur for low energy peaks. The linear least squares fitting procedure is also extended to the general case of a non‐uniform bulk concentration which is illustrated and discussed.
True Auger spectral shapes: A step to standard spectra
Authors: Goto K. , Sakakibara N. , Takeichi Y. , Numata Y. , Sakai Y.
Published: May 2005

We have developed a novel cylindrical mirror Auger electron analyzer with the well defined electric field of 0.1% and the residual magnetic field of less than 1 mG. The CMA has a coaxial electron gun and the entrance angles are 42.3° ± 6°. The theoretically calculated energy resolution of 0.24% was obtained and the transmission was estimated to be 5.6%. This CMA can be used to obtain an absolute Auger electron yield with errors in peak heights of 5%, with an uncertainty in the energy position of 0.1 eV (or 0.01%), and with ghost intensities due to scattering of 0.1–0.2% for energies greater than 10 eV. Samples of polycrystalline gold, silver, and copper have been examined.
Influence of the elastic scattering cross‐section on angle‐resolved reflection electron energy loss spectra of polycrystalline Al, Ni, Pt and Au
Authors: Werner Wolfgang S. M. , Hayek Markus
Published: May 2005

Reflection electron energy loss spectroscopy (REELS) spectra for Al, Ni, Pt and Au were measured in the energy range 300–1500 eV for different scattering geometries. The energy dependence of the loss spectra was found to depend strongly on the shape and the magnitude of the elastic scattering cross‐section. This effect is extremely pronounced in the angle‐resolved spectra, but also persists in the angle‐integrated case. It was moreover observed that the relative intensities of the surface excitations in REELS spectra exhibit a similar dependence on the elastic scattering properties. These experimental observations are in good agreement with MC calculations accounting for elastic scattering through the differential Mott cross‐section and demonstrate that quantitative information regarding the inelastic scattering probability can only be extracted from REELS spectra if the exact shape of the elastic scattering cross‐section is accounted for and a quantitative description of surface excitations is available.
Correction of drift and slope distortions in STM image and scanner calibration
Authors: Yurov V. Yu. , Klimov A. N.
Published: May 2005

STM is a powerful tool for nanotechnology. But it is difficult to carry out correct measurements of distances and angles on the surface via STM image which is often distorted. Drift, slope of sample and indeterminate parameters of piezoscanner are considered as the origin of the STM image distortions. A special algorithm of STM scanning and correction of image of unknown atomic structures is suggested and tested. This algorithm makes it possible to measure three components of the drift velocity and two angles, characterizing the average slope of scanning surface. First, by using this algorithm, the STM calibration can be performed by a known surface structure (for example HOPG) even in the presence of drift. This enables determination of all the three piezoceramics constants of the STM piezoscanner and the deviation of the real scanner axes X and Y from orthogonality. Second, using such calibrated STM and the described algorithm, it is possible to obtain the real STM image and make measurements for unknown surfaces with atomic resolution without the distortions mentioned above. As have been proved, the error of interatomic distance measurements does not exceed 5% (or 0.1 Å) for any direction along the surface, even in the presence of a drift up to 0.4 Å s−1 and the sample slope angle up to 10º.
SiOx surface stoichiometry by XPS: A comparison of various methods
Authors: Alfonsetti R. , De Simone G. , Lozzi L. , Passacantando M. , Picozzi P. , Santucci S.
Published: May 2005

The surface stoichiometry of SiOx thin films (x = 1,…, 2) has been determined by means of x‐ray photoelectron spectroscopy using: (a) two well established methods involving the determination of the area of the O 1s and Si 2p core level peaks and the analysis of the Si 2p line shape, respectively, and (b) the method of the modified Auger parameter recently suggested. The agreement between the different approaches for determination of the stoichiometry of the films indicates the modified Auger parameter procedure as an easy, fast and very reliable method to ascertain the surface stoichiometry of SiOx films.
Simultaneous appearance of sharp and diffuse spots in LEED: Experiments and simulation for Si
Authors: Sakakibara Nobuyoshi , Hisada Yoshiyuki , Hattori Tadashi , Goto Keisuke
Published: May 2005

The LEED technique has been used to analyze HF‐treated actual Si(111) surface. The observed LEED pattern showed a three‐fold symmetrical sharp and hexagonal symmetrical diffuse pattern that is considered to reflect disordered structures in the top surface of the Si. The pattern was compared with a three‐dimensional optical diffraction simulation. In the optical simulation, it was assumed that terminating hydrogen atoms at the Si(111) surface are so arranged that mono‐hydride and tri‐hydride structures are distributed at random. Then hexagonal symmetrical sharp spots and diffuse spots appeared simultaneously. The existence of Si—H, Si—H2, and Si—H3 bonds was confirmed by infrared (IR) spectroscopy.
Quantitative GDOS analysis of oxide films on steels
Authors: Suzuki S. , Suzuki K. , Mizuno K.
Published: May 2005

A method for the quantitative analysis for oxide films on steels by means of glow discharge optical emission spectrometry (GDOS) was investigated. Effective optical emission yields for analysed elements were determined by measuring the emission intensities and sputtering rates of standard samples during discharging under constant conditions. The chemical composition in oxidized samples was obtained from the emission intensities and the effective emission yields, while the sputtered depth was calculated from the emission intensities and effective densities of elements. From measurements of the sputtering of magnetite the effective density for oxygen was estimated as 1820 kg m−3. It was shown that GDOS can be used to determine the quantitative composition and the thickness of the oxide layers on steels.
Recent progress of thin film technology in the automobile industry
Authors: Taga Yasunori
Published: May 2005

This review paper first describes a new concept of the thin film process in material synthesis on the basis of ion‐surface interaction during deposition. Some examples of practical applications of various thin films to automobiles are then given. They include optical thin films, sensor films and surface modification by ion implantation and thin film techniques. Finally, further challenges to applications of thin films to the automobile industry are discussed.
In‐depth homogeneity of vapour deposited multicomponent thin films
Authors: Jehn Hermann A. , Huber Eberhard , Hofmann Siegfried
Published: May 2005

In many fields of advanced technology, thin film properties are fitted to specific requirements by the codeposition of alloying additives. In particular the physical vapour deposition (PVD) techniques allow an almost unlimited range of film composition. The sources can be single or multiple targets. Due to the technical performances of the deposition process, an inhomogeneous in‐depth distribution of the elemental concentration may occur. In the present paper the concentration distribution of multicomponent thin films is discussed using ternary nitride coatings as an example ((Ti, Cr)N, (Ti, Pd)N, (Cr, Pd)N). Oscillating elemental distribution is observed due to the sample rotation during film deposition. The laminate thickness depends on the flux density and rotation speed governing the local growth rate and can range down to few nanometres. The ternary nitride films were deposited by the hollow cathode discharge electron beam evaporation and the magnetron sputter technique, respectively, and were characterized by Auger electron spectroscopy (AES) and glow discharge optical spectroscopy (GDOS).
Ex situandin situcharacterization of surfactant monolayers adsorbed on nonmetallic substrate by infrared reflection spectroscopy
Authors: Mielczarski Jerzy A.
Published: May 2005

The adsorbed (self‐assembled) submonolayers and monolayers structure, orientation and chemical interaction at the interface of nonmetallic (semiconductor) have been studied by infrared reflection spectroscopy. The experimental data collected fromin situandex situmeasurements have led us to propose mechanisms of interaction between surfactants and surfaces. The reflection spectra of the adsorbed layers on different substrates recorded at different angles of incidence and for two polarizations are an excellent source of information about the composition and structure of the layers. The major problem is the interpretation of the recorded reflection spectra which are modified by optical effects, compared with the corresponding transmission spectra of the same layer on a transparent support. The developed method makes it possible to interpret the experimental reflection spectra on the basis of spectral simulation data. It is shown that it is possible to obtain reliable chemical and structural information on the adsorption layer and distinguish it from other observed spectral modifications due to optical effects. The high sensitivity of this method permits the investigation of ultrathin layers (submonolayers). By combination of the simulated and experimental data, the orientation angles of the transition moments of the major infrared bands and the thickness of the adsorption layers were evaluated.
In situ quantitative soft x‐ray spectrometry of thin films synthesized by DC sputtering
Authors: Legrand P. B. , Dauchot J. P. , Wautelet M. , Hecq M.
Published: May 2005

Spectrometry of the soft x‐ray emitted by the growing film or its substrate during sputtering is used to monitor the film synthesis: determination of native oxide on the substrates, film stoichiometry versus experimental conditions, control of oxygen content during nitride synthesis, etc. Quantitative data can be obtained by using a simple exponential profile for the ionization function.
Determination of the depth resolution of Auger electron spectroscopy depth profiles of anodic barrier oxide films on differently pretreated aluminium substrates
Authors: De Laet J. , De Boeck K. , Terryn H. , Vereecken J.
Published: May 2005

The virtual interface width in AES sputter depth profiles of amorphous anodic oxide coatings on aluminium is investigated. Even when the physical film–substrate interface is relatively sharp, considerable deterioration of the depth resolution may be caused by sputter‐induced roughness if sputtering conditions or the sample quality are not chosen properly. The effects of the oxide film thickness, choice of sputter angle and initial substrate roughness on the appearance of the interface width are investigated. A systematic study of the influence of Zalar rotation on the depth resolution is presented. It is concluded that long sputter times, due to film thickness or grazing sputter angles, and initial surface roughness cause a deterioration of the depth resolution. Zalar rotation generally improves the depth resolution for amorphous films, and is particularly indicated for the analysis of very rough samples. The sputter rate of amorphous films however, is insensitive to the use of Zalar rotation.
Pulsed laser induced ablation applied to epitaxial growth of semiconductor materials: Selenides and tellurides plume analysis
Authors: Teghil R. , Guidoni A. Giardini , Mele A. , Piccirillo S. , Coreno M. , Marotta V. , Di Palma T. M.
Published: May 2005

In this study the analysis of ionic and neutral species produced by the interaction between laser radiation and SnSe and SnTe targets is reported. Time of flight mass spectrometry and emission spectroscopy are used for the characterization of the ablated material. Relations between target and plume composition are discussed in order to improve the understanding of the laser deposition process.
Initial growth of AlN on clean and oxidized iron studied by AES and EELS
Authors: Malengreau F. , Vermeersch M. , Sporken R. , Philippe L. , Han B. Y. , Caudano R.
Published: May 2005

We have studied by Auger electron spectroscopy (AES) and electron energy loss spectroscopy (EELS) the room temperature growth of aluminium nitride (AlN) at the surface of clean and oxidized polycrystalline iron. The films were deposited by reactive rf‐sputtering in an N2‐Ar atmosphere. Very low coverages were possible thanks to a precise partial pressure controller based on electron impact emission spectroscopy (EIES).

The AlN/Fe interface study has revealed the formation of an iron nitride at the surface of the substrate and of a compound close to AlN as a first monolayer. AlN clusters grow directly on this nitride layer and we did not detect the formation of any alloy between iron and aluminium. A modelization of the AES signal intensities suggests a Stranski‐Krastanov growth mode.

For the oxidized iron, Auger lines showed an Fe2O3 surface layer on an Fe3O4 film oxide. The former oxide was reduced to Fe3O4 by the incoming aluminium which forms a two‐phase film made of Al2O3 and AlN resulting in an (AlN)x(Al2O3)1‐x stoichiometry. The concentration of this oxide phase decreases after the diffusion of the oxygen stops. Pure AlN begins to grow on this two‐phase film.
Investigation of CdS passivation layers on Hg1−xCdxTe
Authors: Kačiulis S. , Mattogno G. , Viticoli S. , Marini M. E. , Cesqui F. , Alfuso S. , Mercuri A.
Published: May 2005

CdS thin films were deposited on sapphire substrates and on the HgxCd1‐xTe epitaxial and single crystal samples by using chemical decomposition on thiourea and anodic non‐aqueous sulphidation techniques, respectively. The chemical composition and depth profiles of deposited films were investigated by selected area XPS combined with Ar+ ion sputtering. Lateral homogeneity of CdS films was studied by using scanning Auger microscopy. Nearly stoichiometric CdS films were obtained on sapphire and HgxCe1‐xTe. The thickness, chemical composition and sputtering rate at 2 keV ion energy were determined from XPS data. In both cases (either deposited on sapphire or on HgxCd1‐xTe) the CdS films were found to be very non‐homogeneous in thickness.
An XPS study of diamond films grown on differently pretreated silicon substrates
Authors: Arezzo F. , Severini E. , Zacchetti N.
Published: May 2005

X‐ray photoelectron spectroscopy was used to investigate how different pretreatments modify the chemical composition and bonding on silicon substrate surface and, to detect the intermediate phases present at the diamond film interface. The pretreatments were mechanical scratching with a diamond powder, ultrasonic abrasion with diamond suspension and in situ negative dc biasing. The XPS results indicated the presence of hydrocarbons and the formation of new chemical species on the Si substrates such as oxides and carbides. The very important role played by silicon carbide on diamond nucleation and growth was underlined by the phases found at the diamond films interface.
Characterization of nanophase powders prepared by laser synthesis
Authors: Giorgi R. , Martelli S. , Turtù S. , Zappa G. , Borsella E. , Botti S.
Published: May 2005

Sibased (SiCN and SiCAl) nanopowders prepared by laser synthesis process have been studied by XPS and XAES analyses.

The changes of the silicon coordination as a function of the carbon fraction in SiCN powders have been investigated by a detailed analysis of Si 2p and Si KLL lines and the measurements of the Auger parameter Ek(Si KLL) + Eb(Si 2p). The non‐linear dependence of the Auger parameter on the carbon fraction has been interpreted as due to the formation of a carbonitride nanophase, indicating that the ternary powders are not merely a mixture of silicon carbide and silicon nitride.

In SiCAl powders it has been found that the incorporation of aluminium results in a modified structure of the silicon carbide, as shown by the variation of the different spectral features.
Surface versus bulk composition of a phosphate glass
Authors: Meisel W. , Sprenger D. , Gütlich P.
Published: May 2005

Transmission and conversion electron Mössbauer spectroscopy as well as photoelectron spectroscopy were applied to study alterations of the surface layer of an iron containing industrial phosphate glass as compared with its bulk. In the surface layer, after polishing and exposure to ambient atmosphere, Fe2+ is partially oxidized to Fe3+. This oxidation, however, does not increase the O/P ratio in this layer, because it goes along with a strong leaching of network modifiers. This leaching leads to a net decrease of the O/P ratio because it overcompensates the relative oxygen increase by Fe2+ oxidation and by uptake of water.
Investigation of the thermal degradation of polyacrylonitrile on various glasses
Authors: Keller B. A. , Löwe Ch. , Hany R.
Published: May 2005

The thermal degradation of adsorption layers of polyacrylonitrile (PAN) on the surface of Schott 8330 and Schott 8512 glass was investigated by Fourier transform infrared spectroscopy (FTIR), 13C magic angle spinning solid state nuclear magnetic resonance spectroscopy with cross‐polarization (CP‐MAS NMR), and thermal gravimetric analysis (TGA). In contrast to the neat polymer, dehydrogenation of PAN on a glass surface takes place in an inert atmosphere. In the case of Schott 8512 glass (3% FeO) under oxidizing conditions we observed a complexation of nitrile groups to surface species.
Surface structure of AlSn layered systems codeposited in the presence of oxygen
Authors: Kövér L. , Némethy A. , Barna P. B. , Adamik M.
Published: May 2005

AlSn layer structures were prepared by simultaneous evaporation of Al and Sn onto a Si substrate covered by amorphous SiO2, at a substrate temperature of 470–480 K and an oxygen partial pressure of 5 × 10−3 Pa and 1.3 × 10−2 Pa, respectively. The chemical state and the depth distribution of the species formed in the surface layers were analysed by XPS and the cross‐section of the layer system was investigated by transmission electron microscopy. The results obtained confirm the formation of an AlOSn solid phase, segregated to the surface, which prevents the growth of various size Al crystals. At higher oxygen partial pressures a cermet‐like structure is observed above the Al film‐substrate interface, while on the top of this layer an amorphous, homogeneous overlayer can be identified.
Impurity segregation in an Fe‐3.5 at.%Si bicrystal
Authors: Reichl B. M. , Eisl M. M. , Böhmig S. D. , Störi H.
Published: May 2005

In polycrystalline materials, the segregation kinetics is determined by complex transport phenomena like grain boundary diffusion, volume diffusion and surface diffusion. A fundamental investigation of these phenomena was performed, studying the simplest model system, which provides two grains and a well defined grain boundary. In the temperature range between 600 and 750 °C the segregation of Si, P and S in an Fe‐3.5 at.%Si bicrystal was investigated by means of AES. In early segregation runs, diffusion of P and S out of the grain boundary accompanied the segregation via bulk diffusion, while in later runs a combined bulk and surface diffusion was found. Model calculations were performed to analyse the segregation kinetics of subsequent segregation runs.
Evaluation of temperature‐dependent surface chemistry in Zr2Fe and ZrVFe via X‐ray photoemission spectroscopy
Authors: Kovač J. , Sakho O. , Manini P. , Sancrotti M.
Published: May 2005

The near atomic composition and the character of chemical bonds in two non‐evaporable gettering alloys have been investigated via core level (Zr 3d; Fe 2p; V 2p; O 1s; C 1s) XPS (hv = 1253.6 eV). The samples have been measured in UHV after in‐air fracturing and various annealing steps (up to 850 °C). For T > 400 °C a progressive and sizeable decrease of the near surface C content along with an increase in the Zr concentration is observed in both alloys. An annealing‐induced Zr enrichment at the surface is found, the metallic atomic concentrations being permanently far from the nominal bulk stoichiometry. The annealing induces a strong evolution in the chemical bonds, the metallic species being completely oxidized in‐air fractured samples while progressively emerging a metallic character at increasing temperatures. Surface metallization proceeds faster in Zr2Fe than in the V‐containing getter.
Advances in Auger microanalysis for semiconductor technology
Authors: Pamler W.
Published: May 2005

Semiconductor technology issues some of the most intriguing challenges for Auger analysis. The minimum feature size is approaching the quarter‐micron range, while simultaneously, the vertical dimension is being utilized for further integration resulting in an extremely nonplanar surface after numerous processing steps. Although the ultimate limitations of Auger electron spectroscopy combined with sputter depth profiling (lateral resolution < 100 nm, depth resolution < 3 nm) are compatible with such advanced processes, the analysis is often restricted by sample‐related issues. An example is a depth profile through an Al/TiN/Ti metallization system which, under routine analysis conditions, has a depth resolution as poor as several hundred nanometers. Similarly, the lateral resolution accessible in the microanalysis of the sidewall of a conductor line is considerably degraded by scattering of primary electrons into adjacent areas, or the thickness of an oxide film found at the bottom of contact or via holes cannot be determined by sputter profiling because of shadowing of the ion beam and deposition of sputtered material from the sidewall to the bottom.

This paper illustrates that, nevertheless, answers for such difficult analytical tasks can be found by careful optimization of analysis conditions, by simple but unconventional modification of the Auger instrument, or by novel data evaluation methods. With these results, significant input can be provided for process engineering and failure analysis in semiconductor technology.
Low‐energy field emission Auger electron spectroscopy
Authors: Forsyth N. M. , Bean S.
Published: May 2005

As one of the most powerful surface analytical techniques, Auger electron spectroscopy (AES) has repeatedly shown itself to be invaluable in solving problems involving submicron spatially resolved features. Recent developments of this technique towards higher spatial resolution at low primary beam energies and high‐sensitivity chemical state analysis have extended the application of AES as a problem‐solving tool.

The MICROLAB 310‐F from Fisons Instruments (VG Scientific) uses a Schottky field emission source and optimized electron optics to give unparalleled performance at low primary beam energies (3 keV or less) and up to 50 times the usable beam current density when compared to a conventional LaB6 emitter. Two examples of analysis of small features will be shown, demonstrating the advantages of a low primary beam energy for AES analysis.
Secondary ion mass spectrometry of SiGe structures grown by surfactant‐mediated epitaxy and by low pressure chemical vapour deposition
Authors: Herion J. , Siekmann H. , Voigtländer B. , Vescan L.
Published: May 2005

Germanium–silicon heterostructures grown by surfactant‐mediated epitaxy and GexSi1 − x/Si quantum well structures grown by low pressure chemical vapour deposition have been in investigated by secondary ion mass spectrometry (SIMS) using a low energy (2 keV) Cs+ primary beam and detecting negative secondary ions. Depth profiles have been obtained for both types of samples at angles of incidence of 10° and 60° (off normal). Due to the low bombardment energy, the depth resolution was sufficient to resolve the quantum wells, but pronounced matrix effects and interface transients of the secondary ion yield were observed at 10°. It was found that the artefacts are considerably reduced at 60°. It is shown that well‐known qualitative concepts relating to the Cs concentration at the surface can explain most aspects of the results.
Silicon‐insulator interface probing by reflected optical second harmonic generation
Authors: Kravetsky I. V. , Kulyuk L. L. , Micu A. V.
Published: May 2005

Optical second harmonic generation (SHG) has been applied to the study of the silicon–insulator (SI) interface. Results from real‐time measurements of the SHG intensity during etching process of SiO2 and Si3N4 insulator layers are presented and analysed taking into consideration various contributions to the nonlinear polarization in the SI interface such as the silicon substrate, the static electric field, the inhomogeneous deformation and the crystalline oxide interlayer. The symmetry properties of the silicon–insulator interface have also been determined by an analysis of the SHG rotational dependences.
Characterization and reliability of Ti/Ni/Au, Ti/Ni/Ag and Ti/Ni back‐side metallizations in the die‐bonding of power electronic devices
Authors: Scandurra A. , Porto A. , Mameli L. , Viscuso O. , Del Bo V. , Pignataro S.
Published: May 2005

The surface compositions of three different back‐side metals: Ti/Ni/Au 0.1/0.4/0.1 μm, Ti/Ni/Ag 0.1/0.4/0.1 and 0.1/0.4/2 μm and Ti/Ni 0.1/04 μm after thermal treatment at 180°C in air were investigated by means of XPS technique. In the Ti/Ni/Au metal the Ni diffusion through the Au layer was observed, while in the Ti/Ni/Ag metal Ni was not found on the silver surface. Ti/Ni/Ag was found to be sensitive to contamination from elements such as sulphur and chlorine found on the silver surface after thermal treatment, while Ti/Ni metal is sensitive to oxidation. NiO, Ni(OH)2, NiOOH and Ni2O3 species were found on the Ni as deposited surface. The surface compositions were correlated to their wetting property using the Pb88Sn10Ag2 and Pb95.5Sn2Ag2.5 wt.% soft solder alloys. The wetting was studied measuring the contact angle between the surface and the drop of molten solders.
SIMS and X‐ray diffraction characterization of carbon‐doped GaAs, AlxGa1 − xAs films grown by MBE
Authors: Gerardi C. , Giannini C. , Tapfer L. , Fischer A. , Ploog K. H.
Published: May 2005

In this article we report on analyses of GaAs and AlxGa1 − xAs carbon‐doped films, grown by solid source molecular beam epitaxy by using secondary ion mass spectrometry, x‐ray diffraction, and Hall effect measurement.

Carbon is an amphoteric dopant, i.e. it behaves as an acceptor or a donor impurity when it occupies an As or a Ga site, respectively. Comparison between x‐ray diffraction and Hall effect measurements indicates that, for concentrations below 4 × 1019 cm−3, carbon is preferentially incorporated on As site, both in GaAs and AlxGa1 − xAs layers. We find that the presence of Al strongly enhances the substitutional carbon incorporation. SIMS analyses show that the total amount of carbon largely exceeds the substitutional carbon content recorded by HRDXD. The results can be explained considering that carbon is on substitutional as well as interstitial sites. Furthermore, we show that the interstitial carbon concentration can be reduced for both GaAs:C and AlxGa1 − xAs:C growing at an increased As4 flux and higher substrate temperature.
XPS analysis of sol‐gel processed doped and undoped TiO2 films for sensors
Authors: Zanoni R. , Righini G. , Montenero A. , Gnappi G. , Montesperelli G. , Traversa E. , Gusmano G.
Published: May 2005

We have used x‐ray photoelectron spectroscopy (XPS) to probe the actual surface composition of alkali‐doped and undoped TiO2 films prepared by the sol‐gel technique. The role of thermal pretreatments, conducted at various temperatures, and the effect of doping with Na are discussed. XPS results are compared with the electrical response of prototype devices having TiO2 films as the active element, with the help of electrochemical impedance spectroscopy (EIS) measurements.