bluuebunny/crossref_metadata_2025 huggingface dataset:
Static secondary ion mass spectroscopic investigations of deuterated poly (ethylene terephthalate)
Authors: Ramsden William D.
Published: May 2005

The positive and negative ion static SIMS spectra of poly(ethylene terephthalate) (PET) deuterium labeled on either the ethylene glycol units or the terephthalate units were obtained and compared to those of unlabeled PET. These data confirm the ion structure assignments previously reported and allow the assignment of the origins and structures of most of the remaining peaks. The majority of the ions derive logically from the PET structure. A major mode of fragmentation f the PET chains is shown to be the break‐up of ester linkages to produce a carboxylic acid and a vinyl ester. This involves predominate transfer of a hydrogen atom from the glycol unit to the newly formed acid group. Minor, but interesting, ions have been detected which result form the recombination of fragments. These ions have structures not directly derived from the original polymer backbone and may add to the difficulties involved in analyzing the static SIMS spectra of ‘unknown’ surfaces as they suggest atomic connectivities which are not present on the original surface.
AES: Accurate intensity calibration of electron spectrometers—results of a BCR interlaboratory comparison co‐sponsored by the VAMAS SCA TWP
Authors: Seah M. P. , Smith G. C.
Published: May 2005

An interlaboratory study of the calibration of the intensity scales of Auger electron spectrometers has been completed. Thirty‐eight respondees have completed intensity measurements using pre‐calibrated reference materials of Cu, Ag and Au in either the direct or differential modes. The reference material calibrations, made at NPL, involve the recording of true spectra under defined conditions using the metrology spectrometer, in which all instrumental contributions to intensity have been accurately clibrated. The ratio of the spectral intensity form the respondee to that derived at NPL gives the intensity–energy response function of the respondee's instrument. In the direct mode this function may be calibrated at 1 eV intervals from 10 to 2500 eV using any one of the reference materials. By using all three materials it is shown that the average repeatability of the calibrations for the 38 respondees is better than 3% over the energy range 10–2500 eV, improving to < 2% over the range 100–1000eV. The mot serious unknown parameter that has given rise to uncertainty in the intensity function in the past has been the channel electron multiplier ditector efficiency. It is shown here that this term behaves as predicted theoretically and, if ignored, can lead to a factor of two error in intensity. With the present calibration the errors should be reduced to 2% for spectrometers in which there is little internal scattering. In the differential mode twelve peaks are used to define the intensity‐energy calibration. This calibration is less accurate than that in the direct mode and, at the present time, a one‐standard deviation uncertainty of ∼11% is more appropriate. In both modes a loss of intensity owing to multiplier overloading may cause severe errors in the high‐energy peaks.
Impurity migration during SIMS depth profiling
Authors: Vriezema C. J. , Zalm P. C.
Published: May 2005

Among the many processes that affect the accuracy of sputter depth profiling, ion beam‐induced segregation (IBIS) may result in impurity relocations over many micrometres. The most devastating IBIS mechanism of distribution disruption is known to become operative when certain impurities in silicon are profiled under oxide‐forming measurement conditions. Here, we forward evidence that in this particular manifestation of IBIS the bild‐up of an electric field across an insulating surface layer provides an important driving force. Migration towards as well as away from the bombarded surface is observed whenever negative or positive charging conditions are applied. This behaviour has only been observed for elements with a tendency to become singly positively charged ions. In the absence of an electric field, a smaller segregation effect of Group Ia elements away form the surface is shown. Occurrence of this effect for the Group Ia and not for the other elements is indicative of a possible influence of the thermodynamic differences. Further aspects of this field‐induced migration are discussed on the basis of extensive experiments in which the role of the concentration of segregating impurity and the mobility of the impurity in the insulating layer is investigated.

A justification of the methodology adopted is provided. Earlier attempts to explain this particular form of IBIS are examined critically.
Study of concentration‐dependent dielectric properties of n‐type GaAs using variable angle spectroscopic ellipsometry
Authors: Snyder Paul G. , Xiong Yi‐Ming
Published: May 2005

The dielectric function ε spectra of Si‐doped n‐type GaAs crystals at room temperature (296 K) have been determined between 1.53 and 5.01 eV, using variable angle spectroscopic ellipsometry (VASE). Samples with carrier concentrations ranging from 4.6 × 1017 to 3.3 × 1018 cm−3 were measured. The effects of surface microscopic roughness, native oxide overlayer and the subsurface damage were mathematically removed with an appropriate multilayer model. The GaAs dielectric function spectra were modeled using the sum of seven harmonic oscillators, whose center energies, half‐widths and amplitudes were fitting parameters in the multilayer model. It was found that, as the doping level increased, the E1 and E1 + Δ1 peak structures near 3 eV in the ε2 spectrum broadened considerably more than the E0′ and E2 peak structures near 4.7 eV, while the amplitude of the E1 peak decreased with respect to that of the E1 + Δ1 peak. Other effects due to doping were a shift of the ε2 spectrum towards lower energies and a decrease in the amplitude of the E2 peak.
Low‐energy Auger electron spectroscopy of clean and oxidized Cu(100) and Fe/Cu(100) surfaces
Authors: Daas H. Den , Gijzeman O. L. J. , Geus J. W.
Published: May 2005

The background subtraction method for undifferentiated Auger spectra proposed by Peacock is shown to be reliable for the low‐energy Fe and Cu MVV peaks. This is illustrated by the good results obtained for spectra of clean and oxidized Cu(100), Cu(100) containing 0–5 monolayers of Fe and oxidized surfaces. This variety of surfaces made it possible to test the method on spectra with overlapping peaks of different heights and on spectra in which the peak shape changed.

The spectra of the unoxidized Cu (100)/Fe surfaces could be described by weighted sums of the pure Cu and Fe MVV peaks. The background intensity at energies higher than the Cu peak could be used as an internal calibration factor for the spectra. These results are used to calculate the inelastic mean free paths for the Cu and Fe MVV electrons, which were 0.36 ± 0.07 and 0.44 ± 0.09 nm, respectively.

For the oxidized surfaces the Fe (oxide) peak could be extracted by a simple subtraction of a pure Cu MVV peak. This Cu peak apparently did not change shape upon oxidation.
Preparation and surface characterization of silica‐supported ZrO2 catalysts; comparison of layered model systems with powder catalysts
Authors: De Jong A. M. , Eshelman L. M. , van IJzendoorn L. J. , Niemantsverdriet J. W.
Published: May 2005

Model supports consisting of a thin layer of SiO2 on a silicon single crystal have been used to study ZrO2/SiO2/Si model systems made by the same wet chemical preparation methods as used in the preparation of technical catalysts. The results obtained with the models are in good agreement with those on ZrO2 catalysts on porous silica supports.
Energy dependence of UPS peak intensities of physisorbed SF6 layers: Influence of the IMFP
Authors: Klekamp A. , Umbach E.
Published: May 2005

The energy dependence of the electron inelastic mean free path (IMFP) or, more precisely, of the attenuation length (AL), λ(E), may drastically influence the relative intensities of valence peaks, even within the UPS He(II) spectrum of a single species. This is shown for the well‐characterized adsorbate system SF6 on Ni(111), for which five valence peaks are observed in a relatively small energy range of 8 eV. With He(II) radiation the kinetic energies of these peaks range between 23 and 31 eV, and their intensities vary by up to 60% for adsorbate layers of different thicknesses. This potentially confusing effect can be used to determine λ and its energy dependence in the low kinetic energy range (<35 eV). We find λ values between 3.5 and 7.5 monolayers; their energy dependence differs from that expected from the Seah and Dench equation.
High‐spatial‐resolution surface imaging of inorganic and organic structures by multiphoton post‐ionization of sputtered neutrals and time‐of‐flight mass spectrometry
Authors: Tehorst M. , Möllers R. , Niehuis E. , Benninghoven A.
Published: May 2005

Non‐resonant multiphoton ionization (NRMPI) of sputtered atoms as well as resonance‐enhanced multiphoton ionization (REMPI) of sputtered organic molecules in combination with time‐of‐flight mass spectrometry has turned out to be one of the most sensitive techniques for surface analysis. If, additionally, high spatial resolution is demanded the ionization process has to be extremely efficient since only a very limited amount of sample material is available. In preliminary investigations we used ultrashort and intense UV laser pulses (500 fs pulse width) for both elemental and molecular surface imaging. Images of an Ag‐coated Cu grid, an Au‐pattern on Si and surface structures of a biomolecule (tryptophan) and a polymer (polystyrene) are presented. Useful yields of up to 1% are achieved.
Sputtering effects in Si, SiO2 and the Si/SiO2 interface
Authors: Downey S. W. , Emerson A. B.
Published: May 2005

Resonance ionization mass spectrometry (RIMS) is used to determine the optimal sputtering conditions for sampling Si and SiO2 in depth profiling applications. Silicon RIMS signals are proportional to the Si concentration in these materials. Molecular formation during sputtering is significant with Xe+ at low energy (≤4 keV) and a high angle of incidence (∼60° from normal). Sputtering with Ar+ suppresses molecular formation. Because matrix effects are minimized with RIMS, pecularities in profiles at interfaces are easy to observe. The RIMS profiles of Ni and Co implants into SiO2 on Si show evidence of enhanced metal‐silicon bonding at the oxide/substrate interface.
The evolution of atomic scale topography by sputtering erosion
Authors: Carter G. , Nobes M. J. , Stoere H. , Katardjiev I. V.
Published: May 2005

A numerical simulation of mediated random removal of atoms froma square array is presented. The removal probability is weighted according to the local surface orientation in order to model the effect of orientationdependent sputtering yield and it is demonstrated that this results in greatly reduced surface roughness development. This implies improved depth resolution in sputter lepth profiling over that predicted from equal probability random atomic removal processes.
FTIR Study on interfacial interactions between hydrated aluminium and polar groups in ethylene copolymers
Authors: Strålin A. , Hjertberg T.
Published: May 2005

By means of reflection‐absorption infrared spectroscopy, interfacial interactions were studied between hydrated aluminium and two ethylene copolymers, poly(ethylene‐c‐butyl acrylate) (EBA) and poly(ethylene‐c‐acrylic acid) (EAA). The hydrated aluminium surfaces were obtained by immersion in boiling water, which produces a pseudo‐boehmite film consisting of aluminium oxyhydroxide. This films of the polymers were prepared on the substrates by solution casting. Owing to the relatively large surface area of the substrates after hydration, it was possible to obtain spectra only representing polymer interacting with the surface. For EBA, the carbonyl absorbance of the bulk at 1735 cm−1 was displaced to 1698 cm−1 at the interface, owing to an interaction with the hydroxy groups on the hydrated surface. For EAA, on the other hand, a carboxylate was observed at the interface with the hydrated surface. The carboxylate formation and the large displacement of the carbonyl in the case of EBA indicate that strong bonds are formed at the interface. This is also supported by the results of the adhesive strength for EBA, where the locus of failure was changed from adhesive to cohesive.
XPS Study of the reduction of cerium dioxide
Authors: Romeo M. , Bak K. , El Fallah J. , Le Normand F. , Hilaire L.
Published: May 2005

X‐ray photoelectron spectroscopy of cerium oxides is discussed. The well‐resolved 3d3/2 (5d 6s)0 4f0 2p6 peak at 916.70 eV cannot be used for calculating the amount of reduction because the correlation between its intensity and the concentration of Ce(IV) and CE(III) species is not liner. We have therefore develped a complete anlaysis of the whole spectrum. The deconvolution procedure is explained in detail and the method is applied to two examples: a CeO2/Al2O3 sample and a Pd/CeO2 catalyst reduced under hydrogen.
Characterization of the oxidation of tantalum nitride
Authors: Ibidunni A. O. , Masaitis R. L. , Opila R. L. , Davenport A. J. , Isaacs H. S. , Taylor J. A.
Published: May 2005

Sputter‐deposited non‐stoichiometric tantalum nitride films are used for laser‐trimmed thin‐film resistors owing to their stability and processability. The films are stabilized by heating in air to form a passive Ta2O5 film. This passive film can be destroyed if the resistors are exposed to aggressive thermal or chemical conditions. Thus we have studied sputtered TaN films and resistors deposited on SiO2 and Al2O3 substrates and exposed to either KOH solutions or air at 250–500 °C for various times. The oxidized films have been characterized with Auger electron spectroscopy (AES), x‐ray photelectron spectroscopy (XPS), x‐ray absorption near‐edge spectroscopy (XANES) and extended x‐ray absorption fine structure (EXAFS). Chemical shifts in the NOO Auger spectrum have been used to show that the initial fraction of deposited TaN reacts with the SiO2 surface to form Ta2O5. X‐ray photoelectron spectroscopy showed that although significant amounts of oxygen can be present in the sputered films, little of the tantalum is fully oxidized to Ta2O5. X‐ray photoelectron spectroscopy was also used to show that the oxide layer slowly increases in thickness when heated in air. Finally, KTaO3 was identified by XANES on the surface of films exposed to KOH. Once the passive Ta2O5 is converted to KTaO3, further oxidation of the underlying films occurs. The mechanism of oxidation of these films and the unique advantages of each spectroscopic technique are discussed.
A new experimental procedure for the backscattering correction in Auger analysis
Authors: Benhayoune H. , Jbara O. , Thomas X. , Mouze D. , Cazaux J.
Published: May 2005

From the experimental determination of the electron backscattering factor η (using a positively polarized specimen holder) and applying an analytical expression correlating η and the Auger backscattering factor r, we demonstrate experimentally the possibility of correcting Auger spectra and profiles from the backscattering effects.
A calculation method for analysis of SIMS spectra from oxidation of metals in H216O/H218O/16O2 gas mixtures
Authors: Lu Q. , Hultquist G. , Tan K. L. , Åkermark T.
Published: May 2005

A calculation method for the secondary ion mass spectrometry (SIMS) analysis of the reaction of a pure metal with gas mixtures of water and oxygen is introduced. Equation systems are to be solved, each expressed as: Y = A × X, where Y is an amplitude column measured from the SIMS spectrum, A is a matrix constructed from the relative abundances of isotopes of the metal and X is an unknown amplitude column of the relevant species MeaOHb±(a = 1, 2; b = 0, 1, 2 and 3). The applicability of the calculation method has been tested in SIMS analysis of ex situ‐grown iron oxides with different and known 18O contents. In in situ oxidation, measurement of the ratio of H216O/H218O in the metal–water–oxygen reaction allows fractions of O in the species MeaOHb+ that originate from water to be calculated. Data from such calculations have been used to study the initial stage of the reaction of Fe and Cr in H216O/H218O/16O2 gas mixtures. The results are interpreted in terms of coupled/uncoupled reaction type, reactivity of metal to water relative to oxygen in the mixed gas and degree of dissociation of water.
Photoelectron spectroscopic and surface resistance measurements of TiO2 and V2O5 after rare‐gas sputtering
Authors: Sasaki Teikichi A. , Baba Yuji , Yamamoto Hiroyuki , Sasase Masato , Isobe Shoji
Published: May 2005

Insulating to semiconducting transformation was observed for surface layers of the transition metal oxides exposed to 1.5–15 keV He+, Ar+ and Xe+ ions. The surface electrical conductivity increased with the fluence of the ion beams and reached ∼10Ω−1 cm−1 at a fluence of 1 × 1017 Ar+ cm−2. Core‐line splittings in the metal 2p region and preferential losses of the surface oxygen observed in the x‐ray photoelectron spectra give evidence of the formation of the reduced chemical species Ti(II), Ti(III) and V(III). The ion bombardment also brought about the appearance of a new peak near the Fermi level in the UV photoelectron spectra. These observations suggest that electrons in the O 2p orbital are transferred to the 3d‐derived non‐bonding level by the losses of atomic oxygen and thus behave as charge carriers, which causes an increase in electrical conductivity.
Reconstruction of the depth profile from angle‐resolved AES/XPS
Authors: Dwyer V. M.
Published: May 2005

The effects of elastic scattering on the information available from angle‐resolved electron spectroscopies on noncrystalline materials is studied. These effects force the consideration of elastic scattering cross‐sections which are dependent on atomic concentration and therefore on depth. This is done by discretizing the transport equation within a two‐stream/transport approximation. The variation of inelastic mean free paths with composition is also included.

It is also pointed out that, in addition to the ill‐conditioning problems and the possible numerical non‐uniqueness, the inversion of the Laplace transform required for reconstruction of the depth profile introduces a second analytical non‐uniqueness. It is suggested that the reconstruction of the depth profile should be performed using a highenergy peak to obtain an approximate depth profile (large inelastic mean free path, high depth penetration) and that the full quantification should be performed on a low‐energy peak (small inelastic mean free path, low depth penetration).
Structural and electrical study of 〈Au/InP(100)〉 and 〈Au/InSb/InP(100)〉 systems
Authors: Bideux L. , Gruzza B. , Porte A. , Robert H.
Published: May 2005

The mechanisms for the formation of the systems 〈Au/InP(100)〉 and 〈Au/InSb/InP(100)〉 are connected with their electrical properties. By using quantitative AES, a precise knowledge of the atomic mechanisms allows us to perform the desired component such as a Schottky diode. The best results are obtained for the 〈Au/heated InSb/InP〉 system with a barrier height of 0.7 eV.
Influence of metallurgy on the protective mechanism of chromium‐based conversion coatings on aluminum–copper alloys
Authors: Hagans Patrick L. , Haas Christina M.
Published: May 2005

Several important aspects relating to the mechanism of formation of protective Cr‐based oxide films on aluminum alloy 2024‐T3 generated from CrO3 + NaF‐containing solutions were observed with electrochemical, AES and XPS measurements. Although the film deposition rate and surface composition were very much influenced by the presence of both Fe‐ and Cu‐containing intermetallic phases, a uniform composition and thickness was eventually reached with increased coating time. This behavior is believed to be responsible for obtaining corrosion‐resistant films on such heterogeneous surfaces. Surface Cr was consistently found to be in both the 3+ and 6+ oxidation states in an approximately 40:60 ration, respectively, if x‐ray beam reduction of Cr(VI) was accounted for. The enriched Cu layer found on the surface of polished 2024‐T3 was found to remain intact during CrO film formation. The presence of Cr(VI) provides a ‘self‐healing’ aspect to the film's protective mechanism by remaining available for reduction to Cr(III) during oxidative attack. Addition of potassium ferro‐ or ferricyanide to the bath resulted in a film which obtained Fe, C and N enriched at the surface on both the matrix and intermetallic regions. These constituents were found, however, to be enriched and distributed throughout the entire depth of the film on the high Cu‐bearing intermetallic regions, suggesting that the formation of a Cu–ferrocyanide complex is responsible for the benefit derived from these compounds.
Characterization of ni on si wafers: Comparison of surface analysis techniques
Authors: Calaway W. F. , Coon S. R. , Pellin M. J. , Gruen D. M. , Gordon M. , Diebold A. C. , Maillot P. , Banks J. C. , Knapp J. A.
Published: May 2005

The need for improved characterization of materials used in the fabrication of semiconductor devices has been driven by the semiconductor industry's desire to increase device densities on substrate. This need is reflected in the analytical surface science community by efforts to develop methods for detection of trace impurities on semiconductor substrates at extremely low levels. With improvements in standard techniques continually occurring, and with new methods of trace analysis always being developed, it is important to assess the relative abilities of the suite of surface analysis techniques available for materials characterization and to develop well‐characterized standard samples for these comparisons. This paper reports on a collaborative effort to review the capabilities of several approaches to trace surface analysis. As a test case, Ni contamination of Si wafers in the dose range 1014−1010 cm−2 has been chosen. The emphasis of this paper will be on the capabilities of SARISA (surface analysis by resonant ionization of sputtered atoms) as an example of laser post‐ionization secondary neutral mass spectrometry for the detection of contaminants in the near‐surface region. Results on analyses of the same standard samples by other techniques will also be presented. These techniques include total reflection x‐ray fluorescence and heavy ion backscattering spectrometry. The results of this comparison show that there are several techniques that can accurately determine metal contaminations on Si wafers in this concentration range and that the method of choice depends on other considerations, such as speed or accuracy of analysis.
Investigation of diamond films for electronic devices
Authors: Mearini G. T. , Krainsky I. L. , Dayton J. A.
Published: May 2005

Direct dependence of secondary electron emission (SEE) from diamond films due to surface hydrogen has been observed. High secondary yields (14–27) have been achieved in polycrystalline diamond films on molybdenum substrates by varying the hydrogen content on the surface. This was accomplished by driving hydrogen from the bulk by heating the sample, or by adsorption of hydrogen onto the surface from direct hydrogen exposure. However, exposure to an electron beam depleted the surface of hydrogen as a function of current dosage in the energy range 300 eV‐3 keV, thereby reducing the secondary yield to a value as low as 3. Recovery of the secondary yield in the as‐deposited samples was facilitated by saturating the surface with hydrogen, as mentioned, and the recovery time has been characterized. The partial pressure of hydrogen could be adjusted so that the high secondary yield remained stable during beam exposure. The unique properties of these diamond films make them potentially useful as secondary emitters in electronic component designs. A special sample‐holder assembly has been constructed to test the feasibility of using these polycrystalline diamond films as dynodes in an electron amplifier. Actual gain at a hydrogen partial pressure of 1.0 × 10−T Torr was measured to be 2.4 × 104. The maximum gain expected was 2.4 × 105.
Hydrogen profiles in the surface of reduced lead‐silicate glasses
Authors: Rigato V. , Mea G. Della , Pantano Carlo G.
Published: May 2005

It is shown that the thermochemical reduction of alkali‐lead‐silicate glass does not lead to any significant incorporation of hydrogen in the surface, but greatly sensitizes the surface to the chemical and physical adsorption of water. The treatment creates a thin (25 nm) compositionally modified layer of silica‐rich, perhaps microporous, glass at the surface where the hydrogen concentration due to adsorption is irreversible. A more uniform, in‐depth hydrogen profile that extends thousands of angstroms into the treated surface is reversible. The time and temperature of thermochemical treatment influence the initial kinetics of the adsorption. These observations are of practical significance to the behavior of electron multiplier and microchannel plate devices that have been exposed to humid environments. It is demonstrated that vacuum annealing after heat treatment can be used to limit the rate and extent of water adsorption.
Emission of MCs+ secondary ions from semiconductors by caesium bombardment
Authors: Gnaser H. , Oechsner H.
Published: May 2005

The emission of MCs+ molecular ions sputtered from a variety of elemental (Si, Ge, a‐C:H) and compound (GaAs, InP, InSb, ZnTe, ZnMnTe, ZnSe, CdS, CdSe, CdTe) semiconductors by Cs+ ion impact was investigated. The energy spectra of MCs+ species were found to be very similar to that of Cs+ ions but, in most cases, are shifted slightly (∼1 eV) to higher energies. The useful yields of MCs+ secondary ions range from 10−6 (for HCs+) to 10−4 and, for a given molecular species, are largely independent of the specimen. For a series of Ge1‐xOx samples it was established that the GeCs+ intensity is constant up to an oxygen content of ∼10 at.% but the emission of GeOCs+ ions is prominent above this value and constitutes a competing ejection channel.
Surface analysis of oxidized aluminium. 1. Hydration of Al2O3 and decomposition of Al(OH)3 in a vacuum as studied by ESCA
Authors: Nylund Anders , Olefjord Ingemar
Published: May 2005

Pure polycrystalline Al (99.998%) was oxidized in dry oxygen and water. The surface products formed were analysed by ESCA. The thicknesses of the amorphous Al2O3 formed during oxidation for 1 h in dry oxygen at 25°C and 250°C are 14 and 20 Å, respectively. During exposure of the oxidized sample to water a surface layer of amorphous Al2O3 in hydrated and Al(OH)3 is formed by the reaction: Al2O3 + 3H2O⇄2Al(OH)3. The hydroxide is not stable in a vacuum. During analysis in the ESCA instrument, Al(OH)3 is decomposed to Al2O3 and H2O because the equilibrium pressure of H2O is higher than the partial pressure of water in the vacuum system. It is found that a 7 Å thick layer of Al2O3 is formed on the surface of Al(OH)3. The binding energies of the Al3+(2p) and O2−(1s) signals recorded from Al2O3 formed on Al at 22°C and at 250°C are 75.8 and 532.7 eV, respectively. The binding energies of these peaks are 0.6 eV lower for a sample preoxidized at 250°C and then exposed to a humid atmosphere and immediately analysed. It is suggested that the change of the binding energy is due to set up of a space charge during exposure to a humid atmosphere. After exposure for a long time to a humid atmosphere the charging decays and the binding energies approach their normal values.
Practical interest of multicomponent standards for quantitative AES
Authors: Perrot‐Simonetta M.‐Th. , Lorenzon C. , Biscondi M.
Published: May 2005

In this paper, it is first emphasized that the parameters of the classic expression of the Auger signal can be grouped into three terms that are independent of each other: the first relative to recording conditions, the second to an i‐element Auger transition and the last to sample chemistry. Consequently, it is shown that, using a relevant multicomponent standard set, it is possible to free quantitative AES of alloys from experimental conditions. The set of standards has to contain all the elements of the sample; each standard has to contain at least one element of the sample and one element common with another standard. By using the described method, a library of mulitcomponent standard spectra can be created, which can easily be used by other laboratories.
Deposition of cationic yttrium on heterogeneous surfaces
Authors: Davis S. J. , Watts J. F. , Hazell L. B.
Published: May 2005

The cathodic deposition of yttrium on iron and steel surfaces is known to improve the bond strength of joints treated in such a manner. This work explores the effect of large and small heterogeneities on the spatial distribution of the deposited species. Two systems are investigated: 98% iron with micrometre‐scale inclusions, and a micro‐hardness indentation on gold‐coated iron. In the former case yttrium is identified (by XPS and SAM) to have been deposited in two concentration regimes: close to the inclusion (the cathodic area) the concentration is higher than elsewhere, and also contains iron produced by back‐deposition. At the identation the iron substrate is exposed at the corners to provide the prerequisite anodic site, cathodic deposition of yttrium is then observed both within the identation and on the undamaged gold surface at a lower concentration. The provision of spatially resolved analytical information by SAM, time‐of‐flight SIMS and imaging XPS enables the interrelationship of microstructural features and extent of cathodic deposition to be readily appreciated.
Experimental influences on the results of concentration depth profiling by ARXPS
Authors: Ebel H. , Ebel M. F. , Fischer H. , Schoßmann B. , Svagera R.
Published: May 2005

Angular resolved XPS (ARXPS) makes it possible to determine film thicknesses, attenuation lengths of photoelectrons and depth profiles of compositions. The usual algorithms for evaluating thin film results (rectangular depth profile of composition) do not account for influences of count‐rate statistics, finite solid angle of electron acceptance, elastic scattering of electrons and surface roughness on the results. Computer simulations of ARXPS performed on specimens with rectangular depth profiles provide a better understanding of deviations from expected depth responses of composition due to these influences. The dominant influence of surface roughness on the results is demonstrated by a comparison of ARXPS performed on SiO2‐films on monocrystalline and on polycrystalline Si‐wafers.
Interfacial reactions and silicide formation in Si/Ni/Si and Si/Cr/Si sandwich layers
Authors: Zalar A. , Hofmann S. , Pimentel F. , Panjan P.
Published: May 2005

The preparation of well‐characterized silicide thin films for microelectronics needs a control of interfacial reactions and diffusion processes during heat treatment of metal/semiconductor systems. Two sandwich structures of Si(33 nm)/Me(50 nm)/Si(33 nm), where Me = Ni or Cr, with a total thickness of each structure of 116 nm were sputter deposited onto smooth silicon‐(111) substrates. The reactions of both metals with amorphous silicon thin films were activated in a differential scanning calorimeter (DSC), at a heating rate of 40°C/min−1, between room temperature and different higher temperatures. Auguer electron spectroscopy depth profiles showed that the Si/Ni/Si sandwich structure reacted almost completely during heat treatment up to 320°C and formed reaction products with a composition close to Ni3Si2. Selected area diffraction patterns revealed that this is a mixture of Ni2Si and NiSi silicides. A much less pronounced reaction between Si and Cr was observed in the Si/Cr/Si sandwich structure, even with heating to 630°C, resulting in CrSi2 silicide and different Cr–Si solid solutions. The results of AES depth profiling studies of the thermally treated sandwich structures are discussed in terms of diffusion processes, movement of interfaces and formation of silicides. The additional information obtained with differential scanning calorimetry and transmission electron microscopy enables a detailed identification of reaction products formed in the early stage of the thermally treated Si/Me/Si structures.
XPS, SEM and EDX analysis of conditioning film deposition onto ureteral stents
Authors: Reid Gregor , Davidson Ross , Denstedt John D.
Published: May 2005

Ureteral stents are commonly used in urology to drain urine from the kidney. An important complication arises when bacteria or encrustations adhere to the surfaces, causing infection and/or blockage of urine flow. It was hypothesized that upon exposure to urine flow, host elements are deposited as a conditioning film onto the surface of the materials, changing their characteristics. This was studied by x‐ray photoelectron spectroscopy analysis of stents removed from stone‐forming patients and in a stent incubated in vitro with urine. In addition to nitrogen being adsorbed, there was evidence of additional carbon compounds bound to hydroxyl and carboxyl and on some stent surfaces calcium and phosphorus were detected. When a stent was incubated in vitro with urine, nitrogen adsorbed along with a new type of carbon compound bound to hydroxyl. Scanning electron microscopy showed the presence of extensive bacterial biofilms, even after antibiotic therapy, and the existence of tears, erosions or abrasions in the stent surfaces within 2 weeks of implantation. Energy‐dispersive x‐ray analysis confirmed the presence of calcium, magnesium phosphorus and carbonate apatite crystals. These findings have important clinical implications.
Auger electron spectroscopy studies of interdiffusion in electrodeposited amorphous NiP alloys
Authors: Bukaluk Antoni
Published: May 2005

The effect of annealing on the Auger electron depth profiles of electrodeposited amorphous Ni100‐yPy/Ni100‐xPx (15 < x < 32 at.%, y > x) thin film couples is studied at temperatures in the range 190–280 °C. Diffusion coefficients are evaluated by means of the Boltzmann–Matano method. The composition dependence of diffusion coefficients is explained by the role of free volumes in amorphous materials on interdiffusion.
Laser etching of silicon: Dopant desorption, diffusion and segregation during laser induced surface melting
Authors: Desmur A. , Ozenne J.‐B. , Bourguignon B. , Boulmer J. , Budin J.‐P. , Débarre D. , Aliouchouche A.
Published: May 2005

The laser induced redistribution and desorption of dopant atoms (B, As, Sb) is measured in presence and in absence of chlorine at the surface. We define a desorption efficacy which is found to depend strongly on the dopant atom, increasing from boron to arsenic and to antimony. The implications for etching, doping and annealing experiments are discussed.
An XPS valence band study of alkane chains secondary structure
Authors: Riga J. , Delhalle J. , Deleuze M. , Pireaux J. J. , Verbist J. J.
Published: May 2005

Valence XPS studies of well oriented polyethylene mats, deposited on a gold substrate, provide direct evidence of the existence of the fold structure at the sample surface and confirm earlier suggestions that conformation is directly fingerprinted in that energy region of the spectra. These results also provide new insight into the origin of the valence XPS spectra differences, so far unexplained, of n‐tridecane recorded in gas and solid phase.
Surface compositional changes of InP due to krypton ion bombardment
Authors: Malherbe J. B. , van der Berg N. G.
Published: May 2005

Sputtering of the (110) and (100) surfaces of InP by Kr+ ions resulted in a preferential loss of the phosphorus species leaving an In‐enriched surface. The equilibrium Kr+‐sputtered surface composition of InP was determined by means of Auger electron spectroscopy. The sputtered surface composition ratio was independent of crystal orientation and ion energy (between 0.5 and 5 keV). Owing to a lack of other experimental krypton sputtering data, the experimentally obtained surface composition ratios were compared to the Sigmund theory for preferential sputtering in the linear cascade regime. A comparison with the Sigmund spike model showed the absence of spike effects in this krypton ion energy regime. A reasonable agreement was obtained between the experimental results and the Sigmund predictions. There was a correlation between the angle of incidence of the bombarding Kr+ ions and the final surface composition: The preferential sputtering effect became less with increasing angle of incidence θi (measured from the surface normal). The results show that the ratio of the phosphorus to indium compositions, namely X/X ∝ (cos θi)−a with a ≃ 0.24, and where θi is the angle of incidence of the ion beam with respect to the sample normal. This result is explained in terms of a model using the angle dependence of the sputtering yield of the constituent elements.
Small‐area XPS and XAES study of the iron ore smelting process
Authors: Ingo G. M. , Mazzoni S. , Bultrini G. , Fontana S. , Padeletti G. , Chiozzini G. , Scoppio L.
Published: May 2005

The iron ore deposit of Kerry (north‐western Syria) has been sampled; by means of the combined use of small‐area x‐ray photoelectron spectroscopy (SA‐XPS), small‐area x‐ray induced Auger electron spectroscopy (SA‐XAES), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), differential thermal analysis (DTA) and thermal gravimetric analysis (TGA), the smelting process of the most iron‐rich ore has been studied under a CO atmosphere up to 1570 K. Attention has been focused on the chemical aspects involvéd during the reduction of the iron ore and on the chemical composition of the non‐metallic compounds, i.e. the slags, that result from the smelting process. Furthermore, this information has been compared with that obtained from early iron metallurgy slags and artefacts found in north‐western Syria in order to locate the geographical source of the iron ore exploited during the early Iron Age in this region.
Chemical information from Auger data using factor analysis: Some examples
Authors: Chemelli C.
Published: May 2005

Extracting chemical information from Auger data is an arduous task, particularly when signals result from the contribution of several components. The numerical method known as factor analysis (FA) can be powerful in enhancing the presence of poorly visible lineshape contributions and in quantification problems. Nevertheless FA is still little employed in Auger data handling.

This paper deals with applications of Auger data factor analysis to the study of solid state reaction at oxide–oxide and metal–silicon interfaces.

Attention is focused on the details of data pre‐processing, observation of abstract solutions and physical significance of results.
Simulation of insulator charging by a narrow electron beam
Authors: Vicario E. , Rosenberg N. , Renoud R.
Published: May 2005

We are dealing with the problem of the charge distribution within an insulator (present application: SiO2) which is bombarded by a narrow electron beam. The electron trajectories within the sample are simulated via a single diffusion Monte‐Carlo method. A mathematical model is proposed for the potential and the charge density. The development of an electric field, a potential and the broadening of the incident beam are taken into account. These two last distributions appear to have a prominent effect. It is shown that the charge distribution tends to a double layer; the shape and thickness of positive and negative distributions are given.
XPS analysis of lithium intercalation in thin films of molybdenum oxysulphides
Authors: Benoist L. , Gonbeau D. , Pfister‐Guillouzo G. , Schmidt E. , Meunier G. , Levasseur A.
Published: May 2005

Thin films of molybdenum oxysulphides which could be used as positive electrode materials in microbatteries were analysed by XPS. The results have shown the existence of a new environment for molybdenum with S22− pairs, S2− and O2− ions. The evolution of these thin films MoOySz at different stages of their cycle in experimental generators has also been studied; the main elements involved in the redox processes have been characterized: molybdenum atoms with +6 formal oxidation number and disulphide pairs S22−.
Surface modification of PET films with RF plasma and adhesion of in situ evaporated Al on PET
Authors: Le Quoc Toan , Pireaux J. J. , Verbist J. J.
Published: May 2005

PET (Polyethylene terephthalate) films were modified with two different plasmas, nitrogen and oxygen, as a function of treatment times and RF powers. Firstly, the chemical composition of the plasma‐modified PET films was investigated by XPS. In the case of nitrogen plasma, the formation of amine, imine and amide groups is detected. A slight diffusion of nitrogen‐containing species into the PET bulk is also observed by angle‐resolved XPS measurements. The appearance of alcohol, carbonyl and carboxyl functions is observed in the case of oxygen plasma treatment. After thermal deposition of an aluminium film, peel tests reveal that the Al/PET adhesion increases as follows: untreated < nitrogen plasma < oxygen plasma treatment.

Secondly, after sevderal successive depositions of thermally evaporated Al on oxygen plasma treated PET film, XPS was used to study the chemistry at the interface. The XPS results reveal that the additional reactive sites created on the PET surface by the treatment explain the significant improvement in Al/PET adhesion observed for plasma‐modified samples.
Interface analysis of ceramic matrix composites by XPS, AES, SEM and XRD
Authors: Contarini S. , Giunta G. , Loreti S. , Nistico N. , Lambers E. , Holloway P. H.
Published: May 2005

The analysis of interfaces between silicon carbide or carbon fibres and a glassy sol‐gel derived SiO2 matrix in ceramic matrix composites (CMC) is presented. The x‐ray photoelectron spectra (XPS) indicate a differential charging effect on all samples, potentially related to the adhesion strength at the interface. By Auger electron spectroscopy (AES) a silicon oxide layer is found on the surface of SiC fibres while no oxygen is detected on the C fibres. Effects of ageing in air or nitrogen at high temperature for 100 h were also studied. While no crystalline phases are present in the x‐ray diffraction (XRD) patters of sintered samples before ageing, different amounts of an SiO2 (low cristobalite) phase appear on heating at 1200 °C in air or in N2. SEM images indicate concomitant porosity upon ageing. Auger point analysis on the longitudinal fracture surface of the SiC composites aged in air shows a thicker oxide layer, while SiC composites aged in N2 atmosphere show no relevant oxidation but presence of carbon on the fibre surface. The carbon layer at the interfaces correlates with fibre pull‐out observed by SEM on SiC/SiO2 specimens heated in N2. The competition between physical (temperature‐induced) and chemical (gas‐induced) modifications observed by combined surface and bulk techniques is discussed.
XPS and SEM studies of Ca‐ and Ni‐substituted LaCrO3 after quenching from reducing and oxidizing atmospheres at 800 °C
Authors: Glenne Rita , Horst Jens Anton , Jørgensen Sissel , Norby Truls , Seiersten Marion
Published: May 2005

Sintered and polished samples of La1−xCaxCrO3(x = 0.0, 0.1, 0,3, 0.5) and La1−xCaxCr1−yNiyO3(x = 0.3, y = 0.05) were annealed and quenched under reducing or oxidizing conditions at 800 °C and analysed with XPS and SEM. After annealing in H2 + H2O the surfaces of the samples with x = 0.3 and x = 0.5 were enriched in Ca in a 5 nm deep zone. Cr was not enriched and was present in the +3 state. Annealing in O2 + H2O gave Ca enrichment and crystalline outgrowths, increasing with increasing Ca contents. The Cr in the surface was in the +3 and +6 states, and the amount of Cr6+ increased with increasing Ca contents. These observations are assigned to precipitation of CaCrO4 and possibly other phases. The Ni‐doped sample exhibited less grain growth during sintering and less surface recrystallization in oxidizing atmospheres than the corresponding sample without Ni.
An interfacial study of a sigma fibre/Ti‐6Al‐4V composite using scanning Auger/EDX microscopy
Authors: Baker M. A. , Upadhyaya D.
Published: May 2005

The interfacial region of a Sigma fibre/Ti‐6Al‐4V composite has been studied by Auger/EDX microscopy. The SiC fibre has a duplex coating consisting of an inner layer of C and outer TiBx layer. Point analyses, line scans and images were acquired from the fibre/matrix interface region for a specimen taper sectioned at 10° to the fibre axis and a sample fractured in situ along the fibre length. Fracture of the composite reveals the presence of a brittle B rich oxide layer probably of the form TixByO at the boride coating/matrix interface. The fracture path occurs either through this oxide or the graphitic carbon layer. C is shown to have diffused through the entire boride coating. B diffuses from the TiBx layer into the matrix, forming TiB at the interface. The presence of excess boron in the coating and the strong affinity of B for O are proposed as the main driving forces for oxide formation at the TiBx/matrix interface.
Ellipsometric investigation of single crystalline CzSi subjected to hydrostatic pressure
Authors: Kamińska Anna M. , Misiuk Andrzej , Wolf Jürgen
Published: May 2005

The application of ellipsometry to study the SiOx/Si system subjected to hydrostatic pressures up to 1.8 GPa at temperatures up to 1280 °C is described. The theoretical model of defects as the spherical disturbances of material has been assumed. The ellipsometric parameters have been analysed as a function of defects size and density and compared with data obtained by etching and x‐ray methods. The applicability of ellipsometry for near‐surface defect structure analysis has been discussed.
XPS‐investigation of titanium modified MFI‐type zeolites
Authors: Grohmann I. , Pilz W. , Walther G. , Kosslick H. , Tuan V. A.
Published: May 2005

The chemical bonding of titanium in MFI‐type zeolites (Ti‐silicalite) has been investigated using x‐ray photoelectron spectroscopy (XPS). Different titanium silicalites as well as pure titania (anatase) have been analysed. We have found a distinctively higher binding energy of the Ti 2p photoelectrons in Ti‐silicalite than in titania‐ or anatase‐containing silicalite. Ti has the same oxidation state in all solids under study. We attribute the difference in binding energy to different oxygen coordinations of the titanium in the framework of Ti‐silicalite (tetrahedral) and anatase (octahedral). This suggestion is supported by XPS‐studies of TiO2SiO2 glasses and TiO2SiO2 mixed oxides where a similar shift was found. Additional Raman‐spectroscopy investigations of the samples indicate the existence of tetrahedrally coordinated titanium by the appearance of a characteristic band at ∼ 965 cm−1. Non‐framework TiO2 species containing octahedrally coordinated titanium could also be distinguished by XPS. Further Ti incorporation is indicated by the expansion of the unit cell which is related to the Ti 2p intensity for the framework titanium.
Study of the bulk and surface acidity of protonated Y zeolites by TPD and XPS
Authors: Guimon C. , Boreave A. , Pfister‐Guillouzo G.
Published: May 2005

The combined use of temperature programmed desorption (TPD) of nitrogened bases (ammonia, pyridine) and x‐ray photoelectron spectroscopy (XPS) was applied to the study of acidity of HY zeolites with different molar Si/Al ratios (∼ 2.7, 5.8, 24).

N1s binding energies of probe molecules showed two types of sites (Brönsted and Lewis) whose relative proportions varied with pretreatment and desorption temperatures, and a dissociative adsorption of NH3 for dehydroxylated zeolites.

The TPD curves and the XPS quantitative analyses of probe molecule concentration in Zeolites allowed the determination of acid sites distribution in term of strength for the real surface of crystals and for a sub‐surface partially freed of extra‐framework species that cover it. These data showed that the acid sites located in sodalite units are mostly strong and Brönsted type sites.