bluuebunny/crossref_metadata_2025 huggingface dataset:
Electronic properties of disordered anodic TiO2 (001) surfaces: Application of the equation‐of‐motion method
Authors: Tit Nacir , Halley J. W. , Michalewicz M. T.
Published: May 2005

We report calculations of the electronic properties for rutile TiO2 (001) surfaces using the equation‐of‐motion (EOM) method. We use a full tight‐binding Hamiltonian developed by Vos to describe the electronic structure. In contrast to the Green's‐function (GF) method which is traditionally used for such a problem, the EOM method gives excellent results with large systems and any number of defects, and puts no restriction on the range of the impurity potential. There is experimental evidence that the observed gap state at 0.7 eV below the conduction‐band edge is due to an oxygen vacancy. For this reason we study the electronic properties of disordered surfaces as a function of oxygen vacancy concentrations (up to 10%). Our results are applied to the interpretation of recent scanning tunneling Microscopy (STM) experiments on anodic rutile TiO2 (001) films (whose thickness is ∼ 150 Å), and the density of surface defects is estimated. Special care was paid to the study of the nature of gap states. Our results show that these states are localized and play the role of trapping centers which impede the conduction in the films and that no impurity band exists for the studied surfaces. We use both conductivity and local density of states (LDOS) calculations to draw this conclusion. In agreement with experiments, no contribution from gap states in the transport was confirmed in our work. We also report the LDOS calculations on a few sites around the defect at the surface. This in turn gives information about both the spatial decay of the bound‐state wave function (localization) and the existence of the impurity band.
Rapid characterization of an unknown optical coating on soda‐lime silica glass using dynamic SIMS
Authors: Carlson Brad A. , Phillips Bradway F.
Published: May 2005

An unknown optical coating deposited on unpolished soda‐lime silica float glass was analyzed using dynamic secondary ion mass spectrometry (SIMS). This investigation was performed to determine the composition and layering structure of the optical coating. Results obtained in this analysis showed the number and thickness of layers making up the coating, as well as the elemental composition of each layer. More importantly, the entire investigation took less than 2 h to complete. This demonstrates the ability of SIMS to perform a rapid characterization of a complex insulating multilyer thin‐film system deposited on a rough surface.
Application of sample rotation to secondary ion mass spectrometry depth profiling of aluminum metallization
Authors: Stevie F. A. , Moore J. L.
Published: May 2005

Aluminum films sputter‐deposited on silicon have been analyzed using secondary ion mass spectrometry with sample rotation during O2+ ion bombardment. Sample rotation prevented bombardment‐induced topography formation and associated loss of depth resolution. Analysis of silicon and boron ion implants into aluminum showed that, compared with the unrotated sample results, rotation did not significantly affect the implant shape, but dramatically improved the characterization of the interface at the bottom of the aluminum layer. For the analysis conditions used, silicon sputtered at approximately twice the rate for aluminum. Sample rotation allowed the correct sputtering rate to be applied to the layer and substrate and thereby provide an accurate depth scale that was not possible for the poorly defined interface without rotation. Aluminum films deposited on silicon at ambient temperature were shown to have an absence of silicon near the aluminum/silicon interface, whereas deposition at 300° C results in a silicon gradient as the interface is approached. Boron was detected below the 1 part‐per‐million atomic level using sample rotation, and boron at the aluminum/silicon interface was clearly defined.
Quantitative surface analysis of layered materials
Authors: Holloway Paul H. , Bussing Tom D.
Published: May 2005

The effects of concentration variation with depth, C(X), on the quantitative reduction of electron spectroscopic data is discussed. It is shown that when the concentration varies with depth, quantitation of the data is affected by the escape depth of the electron transitions chosen for quantitation. Therefore, accurate quantitation is impossible without knowledge of C(X). A Laplace transform method to determine C(X) from angle‐resolved electron spectroscopic data is reviewed, along with potential problems caused by variation with angle of the escape depth of electrons in the solid, channeling, forward scattering, matrix corrections and surface roughness.
Adhesion study of polyimide to SI surfaces
Authors: Jeong Hyo‐Soo , White R. C. , Chu Y. Z. , During C. J.
Published: May 2005

The blister test is applied to the type of thin‐film structures used in microelectronic packaging. The main advantage of this test is that most of the energy expended is responsible for interfacial fracture, allowing the determination of a fracture energy that closely represents the true interfacial adhesion strength between a thin film and a rigid substrate. It has been proved quantitatively that surface modification contributes to enhanced adhesion. It is found that the critical pressure at which debonding occurs does not correlate with the fracture energy measured in the blister test. Reproducibility of the fracture energy is exceptionally good and allows determination of the optimal thermal condition for promoting adhesion of polyimide on silicon surfaces.
Chromium oxidation states and XPS analysis of the chromia/zirconia system
Authors: Gazzoli D. , Occhiuzzi M. , Cimino A. , Minelli G. , Valigi M.
Published: May 2005

X‐ray photoelectron spectroscopy (XPS) has been applied to the study of the oxidation state variations of Cr ions in the chromia/zirconia system (CrOx/ZrO2) submitted to redox cycles: O2 at 773 K (standard oxidation), CO at 673 K (standard reduction) and H2O after standard reduction at 743 K. The XPS results are compared with those coming from the average oxidation number determination (n) by redox cycling and with electron spin resonance (ESR) analysis, particularly with regard to the Cr(V) identification. The results show that equilibrium adsorption of chromic acid on zirconia gives Cr(VI) species (binding energy ∼ 580 eV). The XP Cr(VI) feature shows a continuous evolution towards reduced chromium states as the samples age. After oxygen treatment, in addition to Cr(VI), the presence of a component at 1 eV lower binding energy is required to reproduce the spectral feature. This component was assigned to Cr(V) on the basis of ESR and average oxidation state results. Thermal treatment in CO (standard reduction) results in a broad (4.5−5.5 eV) and unresolved Cr 2p feature. The presence of Cr(II) at 576.0 ± 0.2 eV was established by curve fitting procedures. Cr(II) is destroyed by H2O treatment at 743 K, with ensuing formation of Cr(III) species.
Interface analysis in polysilicon thin films and poly‐Si/SiO2 systems
Authors: Nakhodkin N. G. , Rodionova T. V.
Published: May 2005

Cross‐sectional transmission electron microscopy (TEM) has been used to study interface morphology in undoped and P‐doped polysilicon films and poly‐Si/SiO2 systems deposited by low‐pressure chemical vapour deposition. Two types of polysilicon interface are found: a ‘toothed’ interface in films with fibrous structure and a flat uniform interface in P‐doped polysilicon films. The conditions for the formation of these interface types have been analysed. The morphology of the poly‐Si/SiO2 interface is studied in relation to its dependence on both the original structure type of the polysilicon films and the oxidation temperature.
Monte Carlo analysis of XPS and REELS spectra obtained at different take‐off angles
Authors: Yoshikawa Hideki , Tsukamoto Tadayuki , Shimizu Ryuichi , Crist Vincent
Published: May 2005

In the previous work such a ‘best‐fit’ loss function for Au was derived from Monte Carlo simulation analysis, which describes the experimental Au 4f XPS background spectrum very well with the approximation that the contribution of the intrinsic energy loss is negligible. This best‐fit loss function was supposed to include considerable contributions of the surface excitations as well as the bulk excitation. In the present work we performed not only XPS but also REELS measurements at different take‐off angles, which allowed us to examine the applicability of the best‐fit loss function to more general cases.

Comparison of experimental results with simulated results has revealed that the contribution of the surface excitation to the loss spectrum is indeed significant, leading to the conclusion that the loss function in XPS and reflection electron energy‐loss spectroscopy (REELS) is directly dependent on the take‐off angle. Contributions from the surface excitation to the background intensity are also discussed.
High dynamic range SIMS depth profiling on in situ ion‐beam‐generated mesas using the ion microscope
Authors: Gillen Greg
Published: May 2005

The dynamic range of SIMS depth profiles of high‐dose ion implants can often be improved by removing the influence of the highly doped crater walls from the depth profile. This is accomplished either by collapsing the primary beam raster or by using specialized sample preparation techniques such as the mini‐chip or dot‐etching methods developed by von Criegern et al. The main limitations with the sample preparation techniques are that they are labor and time‐intensive and are not applicable to all substrate types. By a simple modification of the raster circuits of an ion microscope, it is possible to generate, by sputtering, a mesa structure that is subsequently profiled under normal conditions. This approach offers a rapid, flexible method of mesa preparation that is amenable to all sample materials. The principal disadvantage with the use of the ion microscope for this analysis is that a significant memory effect can result from the dopant species that are sputtered during the preparation of the mesa structure.
Chemical analysis of passivated and oxidized layers on FeCr and FeTi alloys by soft x‐ray absorption spectroscopy
Authors: Soriano L. , Abbate M. , de Groot F. M. F. , Alders D. , Fuggle J. C. , Hofmann S. , Petersen H. , Braun W.
Published: May 2005

The chemical differences between passivated and oxidized layers on 17.5 at.% FeCr and 5 at.% FeTi alloys are analysed by means of soft x‐ray absorption spectroscopy (XAS). The relative absorption strengths were used to obtain a quantitative estimation of the composition of the layers. In FeCr, the passivated layer shows a relative Cr enrichment of 34 at.% with respect to the oxidized surface. In addition, Cr2O3 has been identified as the main oxide formed in the passivated layer of FeCr. By contrast, in FeTi, the results are consistent with the formation of a ternary oxide. The potential of XAS in the study of oxidation and passivation is discussed.
Investigation of the surface activity of corrosion inhibitors by XPS and time‐of‐flight SIMS
Authors: Swift Andrew , Paul Alan J. , Vickerman John C.
Published: May 2005

X‐ray photoelectron spectroscopy (XPS), time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) and infrared spectroscopy (IR) have been used to study the interaction of two corrosion inhibitor blends of unknown composition with an iron surface. The analysis has precisely identified quaternary ammonium and tertiary amine compounds that are key ingredients of each inhibitor blend and has shown that inhibitor A forms a thicker and more effective layer than inhibitor C. Further analysis by angle‐dependent XPS has revealed that, for both inhibitors, the quaternary ammonium and tertiary amine molecules adopt a layered arrangement on the iron surface. No evidence of direct chemical bonding between inhibitor and substrate is identified and no evidence of molecular association of inhibitor molecules is found. A mechanism involving the organized interaction of discrete quaternary ammonium molecules to the iron surface is proposed.
Calculations of electron inelastic mean free paths (IMFPS). IV. Evaluation of calculated IMFPs and of the predictive IMFP formula TPP‐2 for electron energies between 50 and 2000 eV
Authors: Tanuma S. , Powell C. J. , Penn D. R.
Published: May 2005

We have made additional evaluations of the electron inelastic mean free paths (IMFPs) and of the predictive IMFP formula TPP‐2 presented in papers II and III of this series. Comparisons have been made with other formulae for the IMFPs and electron attenuation lengths (ALs). We find substantial differences between our IMFP results for 27 elements and 15 inorganic compounds and the AL formulae of Seah and Dench; these differences include different dependences on electron energy and on material parameters. We present IMFP calculations for Al2O3 and GaAs from TPP‐2 in which each parameter of the formula is varied in some physically reasonable range about the true value for each compound; these results show the sensitivity of the computed IMFPs to the choices of parameter values. Finally, we give a summary of sources of uncertainty in the IMFP algorithm, in the experimental optical data from which IMFPs are calculated, and of the TPP‐2 formula. We conclude that TPP‐2 is robust and useful for predicting IMFPs for electron energies and material parameter values in ranges for which the formula was developed and tested.
Non‐destructive characterization of polymide/copper and polyimide/gold interphases using surface‐enhanced Raman scattering and reflection–absorption infrared spectroscopy
Authors: Young J. T. , Boerio F. J.
Published: May 2005

The molecular structure of interfaces formed by curing the polyamic acid of pyromellitic dianhydride (PMDA) and oxydianiline (ODA) against copper and gold substrates was determined using surface‐enhanced Raman scattering (SERS) and reflection‐absorption infrared spectroscopy (RAIR). It was found that acid groups of the polyamic acid reacted with metal ions on the substrates to form carboxylate salts when the polyamic acid was spin‐coated onto metal substrates. Formation of carboxylates on the copper surface extended several hundred angstroms into the polyamic acid films, while only trace levels of carboxylate were formed on the gold surface. Formation of carboxylate salts suppressed the curing of polyamic acid on copper substrates. However, the degree of curing of the polyamic acid was high on gold surfaces. These results were compared to our previous work concerned with the molecular structure of interfaces between PMDA/ODA polyimides and silver substrates. The extent of carboxylate formation on silver was intermediate between those on copper and gold. Results obtained from SERS and RAIR also indicated that cured polyimide films above the partially cured layers were oriented edge‐on, with the PMDA moieties perpendicular to the metal surface and the ODA moieties mostly parallel to the surface.
Ceramic coating chemically vapour deposited on high speed steel substrates: Scratch adhesion test phenomena
Authors: Naeem Z. , Smith A. B. , Lamsehchi M. , Critchlow G. W.
Published: May 2005

The scratch test is widely used to assess the adhesion of ceramic coatings deposited on cermet and alloy substrates by both physical vapour deposition and chemical vapour deposition (CVD). It has been observed during such tests that, depending on the coating type, complete coating removal from the scratch channels can be preceded by flaking of the coating at the edges of the channels. An attempt has been made to ascertain, for CVD coated powder metallurgy (PM) high speed steel (HSS) cutting tool inserts, whether a relationship exists between the presence/absence and type of pre‐critical load coating flaking observed during scratch testing and interfacial compositional variations determined by Auger electron spectroscopy (AES). Scratch test and AES results are presented for the following CVD coated PM HSS inserts: titanium nitride (TiN) coated, where no flaking has been observed; titanium carbide (TiC) coated, where mixed adhesive/cohesive flaking of the TiC coating has been observed and multilayer aluminium oxide (Al2O3) coated, where adhesive flaking of the Al2O3coating has been observed. In the case of the TiN and TiC coated inserts it is not considered that differences in coating/substrate interdiffusion zone thickness alone are responsible for the observed divergence in scratch test behaviour. Differences in coating microhardness are also suggested to be a significant factor. The behaviour of the multilayer Al2O3 coated insert during scratch testing is thought more likely to be singularly associated with interfacial chemistry.
Surface modification of polymethylmethacrylate by UV light as studied by TOF‐SIMS
Authors: van der Wel H. , Lub J.
Published: May 2005

In the present paper the chemical modification upon exposure with UV light of 185 nm and 254 nm in an Ar atmosphere of the surface of polymethylmethacrylate (PMMA) is studied with time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS). The results show that UV photodegradation of PMMA does not induce large changes in the TOF‐SIMS spectra. However, changes in the relative peak intensities for the photolysed samples and comparison with results from PMMA fragmentation upon ion bombardment show that the photodegradation has proceeded to a considerable extent. In addition, small peaks are observed due to ions that originate from oxidized PMMA groups.
XPS Study of non‐rinse chromate treatments
Authors: Yoshikawa Yukihiro , Watts John F.
Published: May 2005

The formation of a non‐rinse chromate coating on various metal substrates—iron, zinc and Zn–13% Ni—Has been studied by XPS. The coating contains both organic and inorganic species from the treatment bath and varies in composition depending on the amount of reducing agent added to the bath to provide the mixed Cr3+/Cr6+ stoichoimetry. The outer surface of the coating is rich in Cr3+ and there is evidence of a chemical reaction between the treatment solution and the metal substrate. An ultrahigh vacuum (UHV) taper sectioning stage has been used in conjunction with small‐area XPS to probe the interfacial chemistry between the coating and the substrate. The enhancement of Cr3+ at this interface is observed at a higher level than at the outer coating surface. These observations are interpreted on the basis of the reaction mechanism proposed for chromate coating formation.
Spectroscopic studies of the interface built up during the formation of an electropolymerized polyacrylonitrile thin film on a copper surface cathode
Authors: Viel P. , De Cayeux S. , Lécayon G.
Published: May 2005

We present in this work a series of result obtained on the atmospherically oxidized copper‐acrylonitrile system, our aim being to follow the deposition, by grafting and growing, of electropolymerized polyacrylonitrile film. Combining analytical means of electrochemistry—XPS, UPS and infrared reflection adsorption spectroscopy (IRAS)—allows quite an accurate description of this phenomena.

The film was deposited by the imposition of a linearly growing negative tension to the copper electrode dipped in an electroyltic solution containing acrylonitrile. The polarization is stopped at different potentials of the current‐potential characteristic. These potentials correspond to the formation steps of the interface. Thus we describe, successively, the nature of the initial states (atmospherically oxidized copper) and the final states (insulating and covered polyacrylonitrile thin film of 20–30 Å) in relation to the change in density of occupied electronic superficial states.

The appearance of this insulating and covering film is expressed on the current‐potential characteristic by an inhibition peak, named and passivation peak.

Moreover, the non‐stoichiometric character of the superficial copper oxide is identified and permits the use of a low electrochemical potential (before the oxide electroreduction potential) to graft the polymer onto non‐oxidized sites.
Multi‐Spectral imaging in materials microanalysis
Authors: Browning R.
Published: May 2005

Multi‐spectral imaging in materials microanalysis is reviewed, with illustrative results from scanning Auger microscopy and energy‐dispersive x‐ray imaging. A new approach to defining the signal‐to‐noise ratio for multi‐spectral images suggests that the number of resolvable signal levels increases multiplicatively with the number of orthogonal dimensions containing the signal. As the collected signal increases only as the sum of the number of dimensions, this can lead to considerable advantages of multi‐spectral over single‐channel imaging. One disadvantage of multi‐spectral imaging is the large amount of data that are collected. However, in practice, most of the signal in an image can be represented in a few dimensions using principal component analysis. An example of the use of principal component analysis shows that the information in a data set from an electron microscope image of seven energy‐dispersive x‐ray images can be viewed in two or three dimensions and can thus be efficiently presented on a windowed graphics screen.
Angular distribution of electrons elastically backscattered from surfaces
Authors: Dwyer V. M.
Published: May 2005

The experimentally measured angular distribution of electrons elastically backscattered from polycrystalline or amorphous solids exhibts a strong resemblance to the differential cross‐section for single‐atom elastic scattering. Consequently most analytical attempts to describe the problem, which involve some simplifying approximations to this scattering cross‐section, are inadequate in the modelling of backscattered electrons. The present paper represents an attempt to derive a simple analytical approximation that is able to describe such events. This is done by including the first scatteing event exactly and including multiple scattering events using a sort of ‘rectilinear + diffusion’ theory, which has proved to be successful for modelling the depth distribution function used in Auger and x‐ray spectroscopies.

For the cases considered (Ag, Al and Cu at 1 kV), the results compare very well with both experimental data and recent Monte Carlo calculations.
Long‐duration exposure facility: Preliminary observations of the effects of low Earth orbit on MgF2, ThF4 and SiO2 optical materials
Authors: John P. J. , Day A. E. , Haas T. W. , Trumble T. M.
Published: May 2005

Nomarski photography and x‐ray photoelectron spectroscopy have been applied to the study of the effects of low Earth orbit on MgF4 and SiO2 optical coatings. These sample coatings were part of NASA's Long Duration Exposure Facility (LDEF), which flew in low Earth orbit for nearly 6 years. Numerous craters, cracks and other artifacts of the space environment were observed. Oxidation of the fluoride films was also noted.
Electropolymerization of pyrrole on Fe and Pt electrodes in methanol and acetonitrile. Evidence of interfacial layers resulting from accumulation and decomposition of the supporting electrolyte
Authors: Ferreira C. A. , Aeiyach S. , Delamar M. , Lacaze P. C.
Published: May 2005

The partial decomposition of PF6− during pyrrole electropolymerization in methanol and acetonitrile on Fe and Pt electrodes is demonstrated using XPS analysis. A complex mixture of PF6−, fluorides of phosphorus and metal oxides is shown to exist in the interfacial region, probably resulting in a weak cohesive layer unfavourable to the adhesion of polymer films.
Imaging of polymer surfaces using X‐ray photoelectron spectroscopy
Authors: Zupp Terry A. , Fulghum Julia E. , Surman David J.
Published: May 2005

Applications of x‐ray photoelectron spectroscopy imaging in the analysis of heterogeneous polymer surfaces are evaluated using a sample containing tetrafluoroethylene plasma‐deposited onto polyethylene. The C 1s and F 1s images acquired using non‐monochromatic Mg Kα and monochromatic Al Kα x‐ray sources are used to demonstrate good charge stabilization, as confirmed by small‐area spectra. The use of non‐monochromatic flood sources vs. monochromatic focused x‐ray ray sources for image acquisition is discussed. The use of the valence band region for imaging is also demonstrated.
Composition and physical properties of thin a‐C:N and a‐C:N:H films deposited by ion beam techniques
Authors: Zorman Christian A. , Shiao Jeansong , Heidger Susan , Hoffman Richard W.
Published: May 2005

Thin a‐C, a‐C:N, a‐C:H and a‐C:N:H films were deposited onto silicon, glass and graphite substrates using ion beam techniques. Rutherford backscattering spectroscopy and elastic recoil detection analysis were performed in order to determine their atomic composition. The hardness of these films was measured using a Vickers hardness diamond indenter. The as‐deposited a‐C:H and a‐C:N:H films were characterized using optical absorption spectroscopy, while the a‐C and a‐C:N films were studied by Raman spectroscopy. A shift of the absorption edge toward the lower energy region and a lower gap of a‐C:N:H films was observed. The Raman spectra of a‐C:N films show an increase in the I(D)/I(G) ration, as compared to those of non‐nitrogenated diamond‐like carbon films. A possible structure is suggested.
Calculations of electron inelastic mean free paths. V. Data for 14 organic compounds over the 50–2000 eV range
Authors: Tanuma S. , Powell C. J. , Penn D. R.
Published: May 2005

We report calculations of electron inelastic mean free paths (IMFPs) of 50–2000 eV electrons for a group of 14 organic compounds: 26‐n‐paraffin, adenine, β‐carotene, bovine plasma albumin, deoxyribonucleic acid, diphenylhexatriene, guanine, kapton, polyacetylene, poly(butene‐1‐sulfone), polyethylene, polymethylmethacrylate, polystyrene and poly(2‐vinylpyridine). The computed IMFPs for these compounds showed greater similarities in magnitude and in the dependences on electron energy than was found in our previous calculations for groups of elements and inorganic compounds (Papers II and III in this series). Comparison of the IMFPs for the organic compounds with values obtained from our predictive IMFP formula TPP‐2 showed systematic differences of ∼40%. These differences are due to the extrapolation of TPP‐2 from the regime of mainly high‐density elements (from which it had been developed and tested) to the low‐density materials such as the organic compounds. We analyzed the IMFP data for the groups of elements and organic compounds together and derived a modified empirical expression for one of the parameters in our predictive IMFP equation. The modified equation, denoted TPP‐2M, is believed to be satisfactory for estimating IMFPs in elements, inorganic compounds and organic compounds.
Analysis of TdeV guard limiters by surface spectroscopies
Authors: Li X. L. , Paynter R. W.
Published: May 2005

In this study we have analysed coupons cut from one of the internal components of the TdeV tokamak, the stainless‐steel side sheeting of a guard limiter, which was removed when the tokamak was modified at the end of 1988. Depth profiles of the accumulated layer of contaminants have been compiled by a variety of surface analytical techniques, including Auger electron spectroscopy, elastic recoil detection and scanning electron microscopy.

Melting, arcing, bubbles and large exfoliated layers of coating are observed on the surface of the guard limiter. The damage becomes less severe with increasing distance from the plasma and disappears near the wall. The deposits consist of a mixture of carbon, oxygen, stainless steel and Inconel. Most of the deposited impurity is carbon. Of the deposited metal mixture, only about 6% is Inconel, implying that metal impurities originated mainly from the stainless‐steel foils that form a frame around the guard limiter, whereas the Inconel bars were relatively untouched. The metal concentration is a maximum at the surface, coinciding with the maximum concentration of oxygen. Metal carbide appears to be formed with the metal deposits near the surface and at the interface with the substrate, whereas the middle layer consists mainly of ‘amorphous’ carbon.
Present limits to the calculation of auger line intensities for film–substrate systems
Authors: Lee C. L. , Gong H. , Ong C. K.
Published: May 2005

A new and simple algebraic expression for calculation of backscattering factors in the film‐substrate systems has recently been proposed. The limits of its use with the Gryzinski ionization cross‐section to calculate Auger line intensities were, however, not throughly discussed. We have examined more closely its range of validity using Monte Carlo simulation and recent experimental data available. Film‐substrate systems of carbon films on Cu, Sn and Ta substrates and Cu films on C, Sn and Ta substrates were investigated. Our results have indeed shown that there are disagreements. Contributing factors to some of the disagreements include the proposed backscattering factor expression and the ionization cross‐section used. New proposals for quantification were suggested using an alternative interpolation factor taking into account substrate scattering behavior and the Bethe ionization cross‐section. Results of the new proposals did show significant improvements with the use of the Bethe ionization cross‐section for the case of carbon film–substrate systems. Results for Cu film–substrates were not conclusive, with only one evident improvement for Cu/C using the Bethe cross‐section.
SIMS depth profiling with sample rotation in a cameca IMS 3F
Authors: Sykes D. E. , Chew A.
Published: May 2005

The improvements in depth resolution and the suppression of sputter‐induced surface topography obtained using sample rotation during SIMS depth profiling in a Cameca IMS 3F are described. The sample rotation was achieved using a stage that maintains the alignment of the ion optical and rotational axes whilst allowing x–y translation to any position on the sample surface. The material systems studied were a Be‐spike‐doped GaAlAs sample grown by molecular beam epitaxy and a sputter‐deposited film of aluminium on silicon. Significant improvement in depth resolution is shown for buried features in both materials; the sputter‐induced ripple topography was suppressed in the analysis of the GaAlAs; for the aluminium on silicon sample the surface roughening was much reduced but some topography was still present even with sample rotation. The apparent interface width between the 1 μm thick aluminium film and the silicon substrate was reduced from 310 to 45 nm.
Scanning tunnelling microscopy study of tip bias‐induced surface changes on platinum
Authors: Hoffmann‐Millack Britta , Steer William S.
Published: May 2005

Using scanning tunnelling microscopy, platinum wire surfaces have been studied in air and argon under a range of tip bias voltages. It was found that surfaces generally appear smoother with small bias voltages and develop apparent blistering at higher biases. No threshold voltage for the onset of surface roughening has been detected, the process increasing gradually. An explanation for this behaviour is suggested and conclusions are drawn concerning optimum scanning conditions.
Surface analysis of oxidized aluminium. 2. Oxidation of aluminium in dry and humid atmosphere studied by ESCA, SEM, SAM and EDX
Authors: Olefjord Ingemar , Nylund Anders
Published: May 2005

Pure Al (99.998%) and technically pure Al (99.5%) were oxidized in oxygen at room temperature, 250°C and 500°C. The oxidized samples were exposed to a humid atmosphere (80% RH) at room temperature for times ranging from 1 day to 1 month. The reaction products were analysed by ESCA, scanning Auger microscopy, energy‐dispersive x‐ray spectroscopy (EDX) and SEM. The thicknesses of the surface oxides formed during oxidation for 5 h at the same temperatures as above are 15, 22 and 65 Å, respectively. After exposure of the technically pure Al material to a humid atmosphere the analyses show localized corrosion and formation of hydroxide at noble precipitates like Al3Fe and α‐AlFeSi. The distribution of hydroxide particles on oxidized Al can be recorded by SEM owing to the fact that the secondary electron yield of Al2O3 is larger than the yield of Al(OH)3. Exposure of pure Al, preoxidized at room temperature, to a humid atmosphere for 1 week causes a growth of the oxide thickness from 15 to 22 Å. The corresponding growth in a dry atmosphere for the same time is only 1 Å. It is suggested that the growth in a humid atmosphere is due to hydration of Al2O3. Thereby, the oxide becomes thinner and oxidation of Al occurs. The Al(OH)3 formed by hydration is decomposed to Al2O3 in the ultrahigh vacuum (UHV) system and is therefore detected as an oxide growth.
An analytic form for the SIMS response function measured from ultra‐thin impurity layers
Authors: Dowsett M. G. , Rowlands G. , Allen P. N. , Barlow R. D.
Published: May 2005

We present an analytic form for the response function measured in a SIMS depth profile of an impurity layer less than 1 nm wide (a delta layer). Although the process used to evolve the function can be justified on physical grounds, we make no claim that the justification is rigorous or that the function is universal. At present we examine its use in making a consistent and utilitarian definition of frequently employed resolution parameters. The function is found to give an accurate fit (lying everywhere within the statistical noise on the profile over several orders of magnitude in signal intensity) to responses from boron, antimony, germanium and isotopically pure silicon deltas in a silicon matrix, and to silicon, aluminium and beryllium deltas in gallium arsenide. The fit is also good over the full primary ion energy range examined (1–11 keV). There are four fitting parameters for a normalized data set, one related to the depth of the delta below the surface and three independently related to depth resolution. The function has an analytic Fourier transform, and may be used as a smooth, noise‐free substitute for the measured data in profile synthesis (convolution) and in deconvolution whenever convolution is a valid model for the SIMS measurement process.
Sputter‐Induced effects on quantitative GD‐OES depth profiles from hot‐dip zinc‐coated steel
Authors: Karlsson Jörgen , Hörnström Sven Erik , Klang Hans , Nilsson Jan‐Olov
Published: May 2005

Depth profiling using glow discharge optical emission spectroscopy (GD‐OES) is sometimes used by the steel industry to determine the composition of the zinc coating of hot‐dip galvanized steel. It has been observed that the shape of the aluminium profile from an intermetallic phase between the zinc coating and the steel varies from sample to sample, and that the phase is much wider than expected. We have used scanning Auger microscopy (SAM) to study the surface composition and topography of GD‐OES sputtering craters. A surface roughness is introduced during sputtering that considerably deteriorates the depth resolution. The shape of the GD‐OES depth profile in the intermetallic region is related to the microstructure of the zinc coating.
Thermodynamic effects on ion‐beam mixing in SiC–metal systems
Authors: Laidani N. , Calliari L. , Kelly R. , Miotello A.
Published: May 2005

The ion‐beam mixing of SiC‐coated Fe, Cr, Ni, Cu, and stainless steel was investigated, by means of Auger electron spectroscopy, to determine the role of thermodynamics in the process. Both inert (Ar+) and reactive (N+) ions were used at either 30 keV or 160 keV incident energy. A mechanism involving thermally activated motion of bombardment‐induced defects appeared relevant to the onset of a chemical bias in the mixing. Further, the formalism established for describing ion mixing, based on Darken's analysis of chemical interdiffusion coefficients, provided a quantitative interpretation of the results.
Study of passive film formation on Cu–Ni 70/30 alloy in seawater at high temperature
Authors: Beccaria A. M. , Wang Y. Z. , Poggi G.
Published: May 2005

The corrosion mechanism of Cu–Ni 70/30 alloy in quiescent seawater at 80°C with a dissolved oxygen content of .3.0 ppm was studied with electrochemical and free corrosion tests. The passive films formed on free corroded specimens after an exposure time of 10 min–360 h were analysed with XPS.

Free corrosion tests show that Cu–Ni alloy undegoes copper‐selective dissolution; the kinetics of the dissolution process are governed by a transport‐limited mechanism. Electrochemical tests show that the overall corrosion process is under cathodic control and that the reduction of dissolved oxygen is the most important parameter of the corrosion process. X‐ray photoelectron spectroscopy shows that the composition of the passive films changes by changing the exposure time. The main components of the passive films formed on metallic surfaces are Ni compounds after the shorter exposure time and Cu compounds after a longer exposure time.
Factor analysis of Fe M2,3 VV spectra of oxidizing iron: The role of the background in the emergence of ghost components
Authors: Kooi Bart J. , Somers Marcel A. J.
Published: May 2005

The influence of the (correction for the) background in AES spectra on the results of factor analysis (FA) was investigated. To this purpose a set of experimental spectra for the Fe M2,3VV transition, obtained on the oxidation of pure iron, and sets of look‐alike simulated spectra, using a linear combination of two elastic components superimposed on background components, were analysed with FA after different types of treatment of the spectra prior to FA, e.g. differentiation or removal of a particular type of background. In the sets of simulated spectra the roles of a background due to the secondary electron cascade and that due to the inelastically scattered electrons were investigated separately. It was observed that for both types of backgrounds additional principal components with respect to the two elastic components arise, irrespective of the considered treatment of the spectra prior to FA. Results obtained for the experimental set and for the simulated sets with a background originating from the secondary electron cascade were very similar. In the simulated spectra, the origin of the additional components could be identified unambiguously as (an inadequate correction for) the background due to the secondary electron cascade. It is likely that the same origin applies to the additional (third) component emerging on FA of the set of experimental Fe M2,3 VV spectra.
XPS and static SIMS studies of copoly(ether–esters) containing mixed polyether soft blocks
Authors: Burrell Michael C. , Bhatia Qamar S. , Michael R. S.
Published: May 2005

The surface compositions for a series of copoly(ether–esters) are determined from XPS and static SIMS measurements. The copolymers consist of a polybutylene terephthalate (PBT) hard block and a mixed soft block of two of the following polyethers—poly(propylene glycol) (PPG), poly(tetramethylene) oxide (PTMO) and poly(ethylene oxide) (PEO). The surfaces of all the copolymers are enriched in the total polyether soft blocks. Quantification of XPS intensities shows the presence of both polyethers at the surface of these mixed soft‐block copolymers, in relative amounts close to the bulk formulations. In the static SIMS measurements, direct observation of characteristic fragment ions related to the specific polyethers confirms their presence and relative abundance in the surface.
Auger quantitative analysis of brass via target factor analysis
Authors: Calliari L. , Gonzo L. , Micheli V. , Tiscione P.
Published: May 2005

The composition of a brass alloy is determined through target factor analysis (TFA) of Auger data. In spite of spectral interference between Cu and Zn transitions, quantitative information is derived from both the low‐energy and the high‐energy part of the brass spectrum. From the less surface‐sensitive high‐energy region, the nominal composition of the alloy is recovered, whereas from the more surface‐sensitive low‐energy region a definitely higher Zn/Cu ratio is found. This is interpreted in terms of surface segregation of Zn brought about by in situ scribing for surface cleaning.
Application of angle‐resolved XPS algorithms to overlayers and concentration gradients
Authors: Tielsch Brian J. , Fulghum Julia E.
Published: May 2005

Angle‐resolved XPS data from three different sample types was used to compare algorithms for the determination of overlayer thickness and/or concentration gradients. Samples included SiO2 on Si, epitaxial Si0.862Ge0.138 on Si and As implanted in Si. Two algorithms for the determination of overlayer thickness (the relative ratio and patchy overlayer algorithms) and two algorithms based on Laplace transform or regularization methods for the evaluation of concentration gradients were evaluated. For the SiO2 and As‐implanted samples, results representative of the sample type were obtained. However, the composition profiles from the Laplace algorithms showed the expected sharp interface between the Si substrate and the SiGe overlayer, while the regularization algorithm did not. All of the algorithms have correlating parameters, and absolute results depend upon the normalization method, electron attenuation length values and other algorithm‐dependent terms. A comparison of angle‐resolved XPS data from different samples thus requires careful and consistent choices for algorithm parameters.
Effect of silanes on the interfacial compositions of epoxy/metal adhesive bonds: XPS and RAIR analyses
Authors: Hong S. G. , Boerio F. J.
Published: May 2005

The effects of silanes on the interfacial compositions of adhesive bonds formed by curing silanes with the epoxy/amidoamine adhesive against clean and oiled cold‐rolled steel (CRS) and electrogalvanized steel (EGS) substrates are studied using x‐ray photoelectron spectroscopy (XPS) and reflection absorption infrared spectroscopy (RAIR). Silanes used are N‐(2‐aminoethyl)‐γ‐aminopropyltrimethoxy silane (γ‐AEAPS), γ‐glycidoxypropyltrimethoxysilane (γ‐GPS) and γ‐mercaptopropyltrimethoxysilane (γ‐MPMS). The XPS results show that the addition of silanes to the adhesive increases the number of C—O bonds and decreases the N/C ratios in the resins of the interfacial regions. The addition of silane could help the adhesive bond with the oiled substrates. The RAIR results confirm that adding various silanes to the adhesive can change the compositions in EGS/adhesive interfaces differently and affect the preferential adsorption of amino groups from the adhesive on the EGS surface. Silanes can also increase the protonation of amino groups in the adhesive on the clean and the oiled CRS surfaces. However, the absence of protonated amino groups in the adhesive/EGS interfaces indicates that the protonation is metal dependent. X‐ray photoelectron spectroscopy detects two S 2p species in the bonding interface of the specimen prepared using γ‐MPMS‐added adhesive cured against EGS substrate. The higher binding energy S 2p is attributed to the chemical reaction of mercapto groups in the γ‐MPMS with the zinc surfaces.
XPS of oxidized wool fibre surfaces
Authors: Bradley R. H. , Clackson I. L. , Sykes D. E.
Published: May 2005

Oxygen plasma and ultra violet (UV) ozone treatments have been used to oxidize the surfaces of batches of natural wool fibres and woven cloths. The changes in surface composition and chemistry induced by these treatments have been followed using X‐ray photoelectron spectroscopy (XPS).

Oxidation of surface proteinaceous di‐sulphide sulphur to sulphonic acid groups (SO3H) containing S(6+) is shown to occur for both treatments. However, oxidation at levels of approximately 90% is apparent for the UV ozone treatment which is significantly higher than levels achieved using oxygen plasmas (30%). Both treatments also lead to oxidation of surface carbon species. The data presented indicate that the UV ozone treatment used is capable of producing surface sulphur and carbon chemistry of the type usually obtained industrially by wet chemical methods which have the disadvantage of producing chlorinated effluent.
Radiation effects in static SIMS of polymers
Authors: Licciardello A. , Wenclawiak B. , Boes C. , Benninghoven A.
Published: May 2005

The formation of dimerized polystyrene molecules during static SIMS measurements, already reported in a previous paper [Surf. Interface Anal. 20, 549 (1993)] has been further investigated. Samples of styrene oligomers with very narrow molecular weight distribution were prepared by fractionating polystyrene standards by means of supercritical fluid chromatography and then irradiated in situ in a time‐of‐flight SIMS spectrometer. Pre‐irradiated samples have also been studied for comparison purposes. The results obtained confirm that crosslinked (dimerized) species are formed and detected in the very low fluence range, and strongly support the hypothesis that, at least partly, the observation of this kind of Ion beam modification is not due to ion impact overlaps during the measurement, but to primary modification/desorption events.
Mössbauer and Auger spectroscopic investigations of FeSi alloys produced by ion implanatation
Authors: Reuther H.
Published: May 2005

FeSi alloys and compounds are of strong interest because of their electrical and magnetic properties. In thin layers they can be produced by ion implantation. To form iron‐rich alloys Si was implanted at room temperature into iron. Different energies (100, 200, and 300 keV) and ion doses (2 × 1017 to 1 × 1018 cm−2) were applied. The produced layers were investigated by Fe57 conversion electron Mössbauer spectroscopy (CEMS) and Auger electron spectroscopy (AES). CEMS was used to study the phases formed due to the ion implantation. Depending on the implantation parameters different disordered (probably amorphous) FeSi compounds were detected. Annealing of the samples resulted first in the precipitation of crystalline compounds and then in the beginning of the migration of Si out of the investigated range. The concentration profiles were determined with AES. Gaussian shaped Si profiles were found. Depending on the implantation parameters the maximum Si concentration detected was about 50 at.%.
Surface stoichiometry determination of SiOxNy thin films by means of XPS
Authors: Lozzi L. , Passacantando M. , Picozzi P. , Santucci S. , Tomassi G. , Alfonsetti R. , Borghesi A.
Published: May 2005

The surface stoichiometry of SiOxNy thin films has been studied by means of x‐ray photoelectron spectroscopy (XPS). The modified Auger parameter, applied on the Si 2p core level and Si KL2,3L2,3 Auger signal, has been used to calculate the surface composition of SiOxNy thin films prepared using different methods. The results have been compared with those obtained calculating the area under the XPS peaks and the Rutherford backscattering spectroscopy. The good agreement between these data indicates the validity of the modified Auger parameter as an easy and fast method, available in all electron spectroscopy laboratory, to study the surface stoichiometry of Si‐based compounds.