bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of oxide thickness on the degradation of organic silane monolayers on silicon wafer surface during XPS measurement
Authors: Sato Masahide , Furusawa Takeshi , Hotta Takahide , Watanabe Hidetoshi , Suzuki Noboru
Published: March 2006

Many organic materials are damaged and decompose by irradiation of X‐rays during XPS measurements. Factors for the decomposition and/or degradation are considered to be X‐ray, radiant heat and electrons from the X‐ray source, photoelectrons and the inelastically scattered electrons from the sample itself, and so on. We have established the method to evaluate the effect of electrons from the sample by using various inorganic materials as substrates. In this paper, the effect of the thickness of surface oxide layer of silicon wafer on the scission of CCl and CBr bonds in the organic silane monolayers on the wafer surface prepared from chloropropyltrimethoxysilane (CTMS) and bromopropyltrimethoxysilane (BTMS) modifiers has been investigated experimentally. The X‐ray source was monochromatic Al Kα, which eliminates the effect of heat and the electrons from the X‐ray source. Damaging factors evaluated from the decrease of peak intensity and the fitting to the 1st order reaction rate increased with the thickness of the oxide layer and saturated at about 7 nm. Consequently, the electrons from the sample are considered to be one of the main factors for sample degradation. Copyright © 2006 John Wiley & Sons, Ltd.
XPS study of passive films generated on AISI 430 ferritic stainless steel implanted with nitrogen and chromium plus nitrogen
Authors: Abreu C. M. , Cristóbal M. J. , Nóvoa X. R. , Pena G. , Pérez M. C.
Published: March 2006

Surface analysis techniques (XPS and grazing incidence X‐ray diffraction GIXRD) and electrochemical techniques are combined to elucidate the effect resulting from N+ single‐implantation and Cr+ and N+ coimplantation in the formation and evolution of passive layers generated on AISI 430 steel in alkaline medium. Nitrogen implantation leads to CrN together with nitrogen as metastable solid solution. The combined implantation of chromium and nitrogen forms a single well‐defined nitride phase, (Cr,Fe)2N1−x. Copyright © 2006 John Wiley & Sons, Ltd.
Electrical and optical characterisation of TiN porous Si/Si structures
Authors: Benzekkour N. , Gabouze N. , Sam S. , Saoula N. , Henda K.
Published: March 2006

In this paper, the electrical and optical behaviour of a new porous silicon (PS) based structure based on a titanium nitride (TiN) covered PS structure has been studied. Titanium nitride was deposited by radio frequency (r.f.) pulverisation of titanium under nitrogen atmosphere. A rectifying behaviour has been observed from the I–V curves of the structures, which suggests a Schottky‐like junction. The change in the electrical parameters such as the ideality factor, resistivity of the film, series resistance (RS), etc. as a function of deposition time is discussed. The value of the refractive index of the TiN layers is found to be 1.04 to 1.09. The values of the extinction coefficient k indicate that the TiN layers are transparent. In addition, spectral response and spectrophotometric measurements of the TiN/PS/Si structure were performed. Copyright © 2006 John Wiley & Sons, Ltd.
An application of ToF‐SIMS to fine papers
Authors: Starlinger Sandra , Eitzinger Bernhard
Published: March 2006

This paper describes the applicability and limitations of time‐of‐flight secondary ion mass spectroscopy (ToF‐SIMS) for the analysis of paper samples based on studies related to fine papers used in the cigarette industry. The focus was on imaging and appropriate ways of image processing and image analysis. Paper cross‐sections were prepared in different ways to analyse the distribution of individual fillers in a paper sheet and to characterise the distribution of the adhesive between paper layers after further processing. As filler distribution in the z‐direction influences important paper properties like opacity or printability, the first part of the study should help paper manufacturers to optimise pigment distribution for a proper control of the desired paper characteristics. In the second part, the impact of various parameters (paper sizing, glue viscosity, machine settings) on the distribution of adhesives between paper layers in the finished product is investigated after further processing by cigarette makers. Statistical analysis of the data reveals some of the complex interactions of these parameters and confirms and quantifies many facts known only from experience in paper making, paper processing and cigarette manufacture. Copyright © 2006 John Wiley & Sons, Ltd.
Quantitative XPS depth profiling for nickel/4H‐SiC contact with layered structure
Authors: Cao Yu , Nyborg Lars
Published: March 2006

Argon ion etching is used as the precleaning procedure on 4H‐SiC wafer prior to Ni deposition by means of physical vapor deposition (PVD). The thin film Ni/SiC sample is then vacuum annealed at 800 °C for 20 min. The results of XPS depth profiling show that a layered structure of C and Ni2Si forms during the heat treatment. When depth profiling, preferential etching of Si in Ni2Si occurs, the effect of which decreases as ion beam energy increases. Low energy argon ions reduce the atomic mixing. The etch rates of the Ni2Si and C‐rich layers are estimated from the shift of Ni profiles obtained by measuring the Ni 2p3/2 and Ni 3p intensities. At the end, the measured depth profile is reconstructed after correcting for the influence of the electron attenuation length. Copyright © 2006 John Wiley & Sons, Ltd.
An AES study of the initial stages of oxidation of cerium
Authors: Jiangrong Yang , Xiaolin Wang , Chunli Jiang , Hong Xiao , Lei Lu
Published: March 2006

The initial stages of the oxidation of Ce in an oxygen atmosphere at low pressure and room temperature, after cleaning the surface by Ar+‐ion bombardment, were examined by using Auger electron spectroscopy (AES). It is concluded from this work that the interaction of oxygen with cerium proceeds as follows: (i) dissociative chemisorption for oxygen exposure less than 3 L; (ii) formation of nuclei of Ce2O3 that grow until coalescence for exposure between 3 and 25 L; (iii) thickening of the oxide film grown in the previous stage, which follows a logarithmic law up to 50 L and (iv) formation of CeO2 on the surface of Ce2O3, which grows thicker slowly. Copyright © 2006 John Wiley & Sons, Ltd.
Ink identification by time‐of‐flight secondary ion mass spectroscopy
Authors: He A. , Karpuzov D. , Xu S.
Published: March 2006

This work is devoted to the secondary ion mass spectroscopic application in the studies of ink layering on paper. Optical methods are often unreliable in the identification of ink layering on substrates. We demonstrated the power of time‐of‐flight secondary ion mass spectroscopy (ToF‐SIMS) by measuring the secondary ion mass spectra of handwriting on paper and assessing the characteristic ions for each colored ink. These ions were then used to collect images from overlapping handwritings. It was shown that the method could reliably determine which color was applied to the paper first. This work has potential applications in forensic studies. Copyright © 2006 John Wiley & Sons, Ltd.
Influence of temperature on electrical characteristics of CHx/porous silicon/Si sensing device
Authors: Zouadi N. , Belhousse S. , Cheraga H. , Ouadah Y. , Sam S. , Ouchabane M. , Henda K. , Mahmoudi B. , Gabouze N.
Published: March 2006

Recently, a gas sensing device based on hydrocarbons CHx/porous silicon structure was fabricated. The porous samples were coated with hydrocarbons groups deposited by plasma of methane under argon atmosphere. We demonstrated that the structure can be used for detecting a low concentration of a large variety of gases such as ethylene, ethane, CO2, H2 and so on, at room temperature.

In the present work, the sensor has been used as sensing material to detect CO2 gas as a function of temperature. Current‐voltage and capacitance‐voltage characterisations show that sensor characteristics are modified by the temperature environment in the presence of gas. Sensitivity of the devices, response time and impedance response to gases exposure at different temperatures have been investigated.

In conclusion, the sensor shows a rapid and reversible response to low concentration of the gas studied at temperatures in the range 25–100 °C. Copyright © 2006 John Wiley & Sons, Ltd.
Physico‐chemical study of the interfaces of Mo/Si multilayer interferential mirrors: correlation with the optical properties
Authors: Maury H. , André J.‐M. , Gautier J. , Bridou F. , Delmotte F. , Ravet M.‐F. , Holliger P. , Jonnard P.
Published: March 2006

We present the physico‐chemical and optical study of Mo/Si multilayer interferential mirrors (MIM) with a Si thickness of 2 nm and a Mo thickness varying from 1 to 4 nm. In two other samples, barrier layers of B4C have been added either at the Mo/Si interface or at the Si/Mo interface to enhance the optical index contrast in the soft X rays and to minimize the growth of molybdenum silicides. The physico‐chemical analysis is carried out by X‐ray emission spectroscopy (XES) induced by electrons. The Si 3p density of valence states of the silicon atoms that are present in the multilayers are obtained via the analysis of the band Si Kβ (3p→1s transition) emission band. The emission band of the multilayer is fitted by a weighted sum of the compounds likely to be present at the interfaces: amorphous silicon, MoSi2 and Mo5Si3. From the contribution of the silicides, the thickness of the transition layer is determined. The optical analysis is performed by X‐ray reflectivity (XR) at two wavelengths (0.154 and 0.712 nm). The simulation of the results reveals the importance of considering a four‐layer model to describe one period in the stack. Moreover, we evidence the good performance of the multilayer with a Mo thickness of 3 nm. Copyright © 2006 John Wiley & Sons, Ltd.
X‐ray photoelectron spectroscopy surface quantification of sulfided CoMoP catalysts. Relation between activity and promoted sites. Part II: Influence of the sulfidation temperature
Authors: Gandubert A. D. , Legens C. , Guillaume D. , Payen E.
Published: March 2006

The effect of the sulfidation temperature on the nature and amount of active phases of CoMoP‐type hydrodesulfurization catalysts was investigated. An X‐ray photoelectron spectroscopy quantification approach was developed, allowing us to show a direct relation between the amount of mixed CoMoS active phase as determined by XPS and the catalytic activity. XPS, transmission electron microscopy (TEM) and toluene‐hydrogenation activity correlations also showed that the sulfidation temperatures should range between 350 and 500 °C. Under these conditions the catalysts are mainly composed of MoS2 and CoMoS active phases and present a maximum of activity. Copyright © 2006 John Wiley & Sons, Ltd.
Analytical and experimental investigation of the static friction regime for rubber‐rigid ball contact
Authors: Deladi E. L. , de Rooij M. B. , de Vries E. G. , Schipper D. J.
Published: March 2006

The static friction regime is of great importance for systems requiring accurate positioning. The parameters of the static friction regime in terms of static friction force and limiting displacement before gross sliding are investigated for a rubber ball/metal flat configuration. Single‐asperity friction measurements carried out on a Nano‐Tribometer revealed that the static friction parameters depend on various parameters such as normal load (pressure), geometry (radius of the ball) and velocity. The coefficient of static friction decreases significantly by increasing the normal load, while the preliminary displacement increases. Smaller radii of the ball determine a smaller static friction force but a greater limiting displacement. Tests that were run at higher velocities resulted in a decrease of the coefficient of static friction as well as of the limiting displacement. The experimental results show a good agreement with those calculated with the developed static friction model for a load‐controlled case, in which the viscoelastic behaviour of rubber has been modelled by a mechanical model. Copyright © 2006 John Wiley & Sons, Ltd.
Study of the interaction of hydrolysed silane solutions with pre‐treated aluminium substrates
Authors: Franquet A. , Biesemans M. , Terryn H. , Willem R. , Vereecken J.
Published: March 2006

The nature of the interface between thin organosilane bis‐1,2‐(triethoxysilyl)ethane (BTSE) films and alkaline‐cleaned aluminium surfaces has been investigated using XPS. The literature states that an oxane bond (MOSi) is formed by the reaction occurring between OH groups of both the silane and the metal surface. However, in the case of aluminium, the existence of this interfacial bonding is ambiguous. It will be demonstrated that the analysis of a reference silane, i.e. di‐s‐butoxyaluminoxytriethoxysilane (DBAS), having an AlOSi linkage in its chemical structure is very useful for the understanding of the presumed AlOSi bond at the interface between thin BTSE films and alkaline pre‐treated aluminium surfaces. In addition, the influence of the experimental conditions on OH groups, necessary for a good interaction, in the silane solution and at the aluminium surface has been investigated by means of nuclear magnetic resonance (NMR) and infrared spectroscopic ellipsometry (IRSE) respectively. Copyright © 2006 John Wiley & Sons, Ltd.
Impact of Al and Cr alloying of TiN‐based PVD coatings on its cutting performance
Authors: Kovalev Anatoly , Wainstein Dmitry L. , Fox‐Rabinovich German , Yamamoto Kenji , Veldhius Stephen
Published: March 2006

The life of the cutting tools with TiN‐based coatings has been evaluated under turning and end milling. TiAlN and two compositions of TiAlCrN (25:65:10 and 10:70:20) coatings were investigated. The microhardness and the microhardness dissipation parameter of TiAlN and TiAlCrN coatings were measured. The energy band structure of the TiN‐based system has been calculated using EELFS data on surface atomic structure by self‐consistent density functional methods (ZINDO1). It was shown that the addition of Al to the TiN coating significantly reduce the inhomogenity of the electron density distribution within the volume of the molecules and a reduction in the chemical reactivity of the TiAlN coating. The addition of chromium to the TiN‐based nitrides also changes their electron structure decreasing the ion‐covalent character of the interatomic bonds of the crystal lattice while the hybridization of the d π‐electronic states responsible for the metallic atom bonds within the crystal lattice. The probability of the electron transfer to the condition zone also increases. All these features explain the phenomenon of the plasticity improvement in the TiN‐based compounds alloyed with Cr. Simultaneous addition of Cr and Al in the complex TiN‐based nitride weakens the long‐range bonds within the crystal lattice and reduces the polarity of these bonds down. This results in the enhancement of the plasticity of these compounds and improves the life of coated end‐mill cutters. Copyright © 2006 John Wiley & Sons, Ltd.
XPS and contact angle study of N2 and O2 plasma‐modified PTFE, PVDF and PVF surfaces
Authors: Vandencasteele Nicolas , Merche Delphine , Reniers François
Published: March 2006

Poly tetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF) and polyvinyl fluoride (PVF) polymer surfaces were exposed to a remote N2 or O2 r.f. plasma. The effect of the plasma power and treatment time on the surface energy and the surface composition were studied by static water contact angle (WCA) and X‐ray photoelectron spectroscopy (XPS). In every case, a strong defluorination of the surface was observed. Except for PTFE treated by oxygen, all the surfaces became more hydrophilic after plasma treatment, owing to the grafting of polar nitrogen or oxygen functions. The kinetics of defluorination and grafting seems to be favoured for PVDF and PVF surfaces. Copyright © 2006 John Wiley & Sons, Ltd.
Detection and analysis of nitrogen‐containing pesticides in environment by surface‐ionization methods
Authors: Khasanov U. , Rasulev U. Kh. , Usmanov D. T. , Iskhakova S. S.
Published: March 2006

The results of a study of the possibilities of surface‐ionization mass spectrometry (SI/MS) and atmospheric‐pressure thermodesorption surface‐ionization spectroscopy (APTDSIS) for high‐sensitivity and selective detection and identification of nitrogen‐containing pesticides are presented for some trisubstituted 1,3,5‐triazines (prometryne, atrazine) and aromatic amines (trifluralin). An oxidized W band in vacuum (SI/MS) and oxidized Mo crystals doped with Ir in air (APTDSIS) were used as ion emitters. The SI mass spectra of pesticides have a small number of lines and consist of the ion lines (M + H)+, M+, (M − H)+ and (M − R)+, being the products of chemical reactions in the adlayer (M is the molecule; H is the hydrogen atom; R is the radical). The herbicide molecules are ionized by SI with high efficiency. The APTDSIS spectra of pesticides have two characteristic maxima connected with energy of sublimation and desorption. The SI efficiency increases in the order 2.5, 35 and 72 C/mol for trifluralin, atrazine, prometryne, respectively, and is within the linear range of the concentration dependence of 2–4 orders of magnitude. The results obtained by the SI/MS and APTDSIS methods have been compared with those obtained by GC/MS with electron ionization. Copyright © 2006 John Wiley & Sons, Ltd.
Structural and electrical properties of thin d.c. magnetron‐sputtered gold films deposited on float glass
Authors: Markert Christian , Lützenkirchen‐Hecht Dirk , Frahm Ronald
Published: March 2006

The combination of in situ electrical resistivity measurements and ex situ tapping‐mode atomic force microscopy (AFM) in air was used to study the surface topography and the electrical properties of thin d.c. magnetron‐sputtered gold films on float glass substrates. In particular, the influence of the deposition temperature and a subsequent isochronous annealing process on the electrical resistivity and the surface structure of the polycrystalline gold films were analysed. The results show that a minimum surface roughness of about 0.4 nm was achieved for a deposition temperature of about 350 K. After the annealing process, an increase of the surface roughness and the lateral crystallite size was observed in general, suggesting that the measured decrease in resistivity during annealing is not related to a smoothing of the surface, but to the decrease of the grain‐boundary scattering of the conduction electrons. Assuming that the annealing processes are diffusion‐limited reactions, we calculated the corresponding activation energies from the irreversible branch of the annealing curves, yielding values of about 0.6–1.0 eV, which also correspond to grain‐boundary diffusion. Copyright © 2006 John Wiley & Sons, Ltd.
ZnO thin films on aluminized steel by spray pyrolysis
Authors: López Ibáñez R. , Romero R. , Martín F. , Ramos‐Barrado J. R. , Leinen D.
Published: March 2006

Spray pyrolysis is a low‐cost technique and results in minimal waste production when using adequate precursors. The process allows the coating of large surfaces and is appropriate for adaptation into an industrial production line. The aim of this work has been to obtain, by spray pyrolysis, thin and compact ZnO films on 30 × 40 cm galvanized steel sheets heated by high frequency magnetic induction and using zinc acetate precursor in aqueous spray solution. The work includes a study of optimized deposition conditions (substrate temperature, precursor solution concentration, flow rate and spray time) controlled ex situ by SEM, XPS, XRD and UV‐Vis‐NIR and FTIR diffuse reflectance spectroscopy, in order to obtain an effective barrier coating with low thermal emittance when the steel is used as a base material for solar thermal devices. Our results show improved anti‐corrosion performance when the substrate coverage is guaranteed, substrate temperature and deposition time being the main factors to accomplish the optical requirements of the ZnO‐coated galvanized steel. Copyright © 2006 John Wiley & Sons, Ltd.
Grafting of bifunctional fluorinated polyether molecules on metallic surfaces: application to the protection of electrical contacts
Authors: Noël S. , Lécaudé N. , Alamarguy D.
Published: March 2006

Protection of metallic surfaces against corrosion and wear is of high economical interest, particularly in the field of electrical contacts. New types of bifunctional fluorinated polyethers have been synthesised in order to elaborate innovative protective coatings. The films were elaborated by dipping the metallic substrates in solutions comprising the molecules and a perfluorinated solvent. Two linear perfluorinated polyethers (PFPE) were studied, having either highly or partially fluorinated thiol end groups.

Galvanic gold samples were coated by dipping for a very short time in order to simulate an industrial process. The characterisation of the formed layers was performed by XPS. It was shown that despite the very short dipping time, the sulphur atoms of the thiol end groups were grafted to the gold surface. Different grafting kinetics were observed for the two types of molecules, which explains different behaviours were recorded during friction experiments. These molecules offer very promising properties in the field of surface modification and protection. Copyright © 2006 John Wiley & Sons, Ltd.
Comparative study of the interfacial characteristics of sputter‐deposited HfO2 on native SiO2/Si (100) using in situ XPS, AES and GIXR
Authors: Tan Ruiqin , Azuma Yasushi , Kojima Isao
Published: March 2006

The HfO2/SiO2/Si, Hf/SiO2/Si and HfO2/Hf/SiO2/Si interfaces formed by rf magnetron sputtering deposition were comparatively investigated using in situ high resolution X‐ray photoelectron spectroscopy, auger depth profiling and grazing incident X‐ray reflectivity (GIXR). The reactive deposition of HfO2 directly on native SiO2/Si (100) leads to an extraordinarily thick Si‐rich interface of about 3.33 nm, which will limit the capacitance of high‐κ films. To suppress the growth of the unexpected interface, it has been found that the pre‐deposition of Hf (about 1 nm) is effective. The Hf radicals reduce SiO2 to metallic Si to form HfO2 and partly result in HfSix. After subsequent reactive deposition of HfO2 on Hf/SiO2/Si stacks, the Hf‐rich silicates interlayer is as thin as 1.88 nm, calculated as an equivalent thickness of SiO2. All the XPS, AES depth profiling and GIXR results show a good coincidence with each other. Copyright © 2006 John Wiley & Sons, Ltd.
XPS investigation of CoOx‐based MRISiC structures for hydrocarbon gas sensing
Authors: Comini E. , Cusmà A. , Kaciulis S. , Kandasamy S. , Padeletti G. , Pandolfi L. , Sberveglieri G. , Trinchi A. , Wlodarski W.
Published: March 2006

Sensors based on metal–reactive insulator–silicon carbide (MRISiC) devices are widely employed for monitoring industrial processes because of their resistance to harsh and high‐temperature environments. MRISiC structures composed of the films of Pt and cobalt oxide (CoOx) were fabricated and investigated. The films of Pt and CoOx were deposited on SiC substrates by using r.f. magnetron sputtering. The depth profiles of their chemical composition were studied by XPS combined with cyclic Ar+ sputtering. The surface morphology was investigated by AFM. XPS analysis of the Co 2p peaks and shake‐up satellites revealed the presence of the mixed‐valency oxide Co3O4 on the sample surface, while deeper in the film only stoichiometric CoO was present. The platinum film deposited on the top of cobalt oxide was found to be metallic and uniform enough to inhibit further oxidation of Co2+. The hydrocarbon (propene) gas sensing performance of the Pt/CoOx/SiC devices was studied. Copyright © 2006 John Wiley & Sons, Ltd.
Electrostatic electron spectrometer based on two cylinders without axial symmetry
Authors: Varga D. , Tőkési K.
Published: March 2006

The calculated electron‐optical properties of a mirror type electrostatic electron spectrometer are presented. The analyzer consists of two cylinders without axial symmetry. We show that a spectrometer having such a construction has second‐order focusing properties with remarkable dispersion. Copyright © 2006 John Wiley & Sons, Ltd.
X‐ray photoelectron spectroscopy study of energy‐band alignments of Lu2O3 on Ge
Authors: Perego M. , Seguini G. , Scarel G. , Fanciulli M.
Published: March 2006

X‐ray photoelectron spectroscopy (XPS) was used to investigate the band alignment of lutetium oxide films with a germanium substrate. Lu2O3 films were grown on Ge (100) by atomic layer deposition. The conduction ‐ (CBO) and valence ‐ (VBO) band offsets of the Lu2O3/Ge heterojunction were determined to be 2.2 ± 0.1 and 2.9 ± 0.1 eV respectively. Internal photoemission measurements performed on metal‐oxide‐semiconductor devices gave a CBO of 2.1 ± 0.1 eV and a VBO of 3.0 eV, in excellent agreement, within the experimental error, with the values obtained by XPS. Copyright © 2006 John Wiley & Sons, Ltd.
In‐depth composition study of zirconia‐coated steel sheet by XPS
Authors: López R. , Romero R. , Martín F. , Ramos‐Barrado J. R. , Leinen D.
Published: March 2006

Zirconia was deposited by spray pyrolysis on large‐area aluminized steel sheets using two different types of heat sources: infrared radiation or white light. XPS in‐depth composition study has shown that the carbon concentration is 4 at.% when using white light but 15 at.% when using infrared radiation. This carbon is found as zirconium carbide, formed as a diluted phase in the zirconia coatings. In the case of using infrared radiation, reflectance spectroscopy revealed a partial degradation of the optical properties of the coatings due to an incomplete pyrolysis of the precursor. These findings are of direct interest for unglazed solar façade elements made of steel, in which the zirconia coating will act as a barrier layer against the degradation of the steel sheet during long‐term outdoor exposure. Copyright © 2006 John Wiley & Sons, Ltd.
XPS characterization of anodic oxides grown on biocompatible Ti–50Zr alloy in different acid electrolytes
Authors: Ferreira E. A. , Oliveira N. T. C. , Biaggio S. R. , Nascente P. A. P. , Rocha‐Filho R. C. , Bocchi N.
Published: March 2006

In this work, X‐ray photoelectron spectroscopy (XPS) analyses were performed in order to identify the surface composition of oxide films electrochemically grown on Ti–50Zr and to verify whether anions from the electrolytes (H3PO4, H2SO4, and CH3SO3H) were incorporated into these oxide films. For all three electrolytes, an oxide film surface enrichment in Ti was observed, being more pronounced in the case of the H3PO4 solution. After sputtering, the alloy oxide film obtained in the H2SO4 solution presented the highest deviation from the equiatomic stoichiometry. Phosphorus‐containing species were incorporated into the oxide film grown in the H3PO4 solution, but no sulfur‐containing species were detected in the films grown in the H2SO4 and CH3SO3 H solutions. Copyright © 2006 John Wiley & Sons, Ltd.
Correlation between optical properties and electronic parameters for mixed oxide thin films
Authors: Gracia F. , Yubero F. , Espinos J. P. , Holgado J. P. , González‐Elipe A. R. , Girardeau T.
Published: March 2006

SixTi1−xO2 optical thin films with variable compositions varying from pure TiO2 to pure SiO2 have been prepared by ion beam induced chemical vapor deposition (IBICVD). It has been found that the refractive index of the films increases with the content of titanium, from about 1.46 to 2.35. Band gap energies have been determined by optical methods and reflection electron energy loss spectroscopy (REELS), both techniques showing a similar evolution consisting of a sharp decay from the value of pure SiO2 to the samples with 2% Ti and then a smoother decrease up to the value of pure TiO2 (i.e. 3.2 eV). Changes also occur in the value of the binding and kinetic energies (KEs) of the Ti and Si photoemission and auger peaks, respectively, as measured by X‐ray photoelectron spectroscopy (XPS). The refractive indices of the films have been compared with the value of the auger parameters of Ti and Si. A good correlation exists between these two parameters as a function of the titanium content. This confirms that both depend on the polarizability of the medium and shows that XPS can be used for the assessment of optical properties of complex oxide materials. Copyright © 2006 John Wiley & Sons, Ltd.
Visualization of early stages of corrosion processes by a chemographic method
Authors: Yelizarov M. A.
Published: March 2006

Corrosion of duralumin was studied in sandy soil conditions with different moisture and ion concentrations. The influence of these factors on initial (the first hours) corrosion stages was visualized by a chemographic method in which a film works as an indicator of the volatile products released during the electrode process, which may transform silver to the metallic state. Atomic hydrogen acts as such a product during metal corrosion. As a result, the pattern of optical density in a chemogram maps the corrosion activity of a specimen surface. The soil condition was checked by using its conductance. Two mechanisms of conductance were differentiated and analysed in terms of the percolation theory for low‐moisture soil (<1% mass moisture) and high‐moisture soil. It was found that the ion concentration in solution has no practical influence on conductance at low moisture. Traced reactions of duralumin corrosion show that this process is different in low‐ and high‐moisture soils. Pitting corrosion was visualized at the very beginning, with pits being located immediately and precisely on the surface of model specimens. Patterns of duralumin corrosion were traced in cases when cathode protection was applied and when a duralumin specimen worked as a sacrificial anode. The results of this research can be used to develop electrochemical corrosion protection systems for underground metal constructions. Copyright © 2006 John Wiley & Sons, Ltd.
Quantification and IMFP determination of multilayer Langmuir–Blodgett films by AFM and XPS measurements
Authors: Sato Masahide , Tsukamoto Naoto , Shiratori Tsubasa , Furusawa Takeshi , Suzuki Noboru , Tougaard Sven
Published: March 2006

XPS spectra of cadmium arachidate Langmuir–Blodgett (LB) multilayer films have been investigated by quantitative peak shape and intensity analysis (the Tougaard method). The structure and film thickness of cadmium arachidate multilayer (1–21 layers) LB films on silicon wafers were observed by atomic force microscopy (AFM). The monolayer and bilayer thickness of cadmium arachidate LB film was determined to be 2.3 and 5.5 nm from AFM images of partially scratched multilayer LB films. The angle‐resolved XPS (ARXPS) spectra of these LB films with well‐defined thickness were analyzed by the Tougaard method. The inelastic mean free paths (IMFPs) in the LB film were determined to be 35.5 Å at 1382 eV and 29.1 Å at 1078 eV from analysis of ARXPS spectra taken at several emission angles (10°, 32° and 45° from the surface normal). These values are in good agreement with the reported values of bulk organic materials. Copyright © 2006 John Wiley & Sons, Ltd.
In situ electrochemical lithium intercalation into amorphous oxide thin films
Authors: Haake U. , Lützenkirchen‐Hecht D. , Frahm R.
Published: March 2006

Lithium intercalation and de‐intercalation in amorphous MoO3 electrodes were investigated using electrochemical techniques and in situ grazing incidence reflection mode X‐ray absorption spectroscopy. A new electrochemical cell suited for in situ investigations with X‐rays under grazing incidence in a protective He atmosphere was built. A Kapton sealed electrolyte compartment, the bottom of which was the amorphous MoO3 working electrode, was placed in this steel container so that a well‐defined electrochemistry analysis was possible in parallel to the X‐ray investigations. We present the results of potentiodynamic polarization experiments, as well as potentiostatic current transients, in close connection to surface‐sensitive in situ X‐ray absorption spectra. The results show that the Mo6+ ions of the amorphous oxide electrode are reduced by electrochemical lithiation, leading to a formal Mo5+ oxidation state. Angle‐dependent experiments reveal that the intercalation is not complete for the applied conditions, i.e. the Li ions are not homogeneously distributed in the entire volume of the amorphous working electrode. In addition, a certain amount of Li remains in the Mo oxide electrode after a complete intercalation/de‐intercalation cycle. The results suggest that Li ions are accumulated at the electrode/electrolyte interface during both intercalation and de‐intercalation. Copyright © 2006 John Wiley & Sons, Ltd.
Ripple structures developed on graphite layers during ion‐sputtering
Authors: Kovač J. , Zalar A. , Praček B.
Published: March 2006

Surface roughness caused by ion bombardment can influence the sputtering yield and deteriorate the depth resolution during depth profiling. In this work, the roughening of an amorphous graphite layer 60 nm thick on a Ta layer 50 nm thick deposited on a smooth silicon substrate was studied by atomic force microscopy (AFM). The AFM measurements were carried out on the surface of the as‐deposited sample, and after ion‐sputtering with a 1 keV ion beam at ion incidence angles of 22°, 49° and 71° in the middle of the carbon layers and at the C/Ta interfaces. Ion bombardment was performed with one and two ion beams on stationary and rotating samples with an initial surface roughness amplitude Ra of 0.13 ± 0.05 nm. On stationary samples, in the graphite layer as well as at the C/Ta interface, ripple formation on the nanometre scale was found at ion incidence angles of 49° and 71°. Depending on the sputtering parameters, the wavelengths of the ripples were found to be between 18.0 ± 4.0 and 31.4 ± 4.0 nm and the amplitude between 1.0 ± 0.2 and 4.9 ± 0.2 nm, yielding a roughness parameter Ra of between 0.4 ± 0.1 and 1.6 ± 0.1 nm measured over a 1 × 1 µm area. Unexpectedly, a stronger ripple formation in the graphite layer was found at a grazing ion incidence angle of 71°. The ripple formation is suppressed by sample rotation. Copyright © 2006 John Wiley & Sons, Ltd.
Development of a ToF version of the desktop MiniSIMS: instrument design and applications
Authors: Cliff B. , Eccles A. J. , Jones C. , Long N. , Vohralik P.
Published: March 2006

The Millbrook MiniSIMS remains a unique concept in SIMS instrumentation, incorporating static, imaging and dynamic SIMS in a single compact desktop unit. The instrument is successfully being used in a wide range of applications, in which its low cost and high sample throughput are more important than the higher specification or flexibility in configuration of conventional instrumentation. The original MiniSIMS was designed around a quadrupole mass analyser, selected as the only type able at the time to meet the size and cost criteria appropriate to a desktop instrument. However, the sequential mass scanning needed to acquire a full spectrum is inefficient and the accepted static SIMS limit may often be exceeded during analysis of small areas. Therefore a time‐of‐flight (ToF) version has been developed in order to increase performance in areas where a low primary ion dose is critical to the analysis. Such analyses include organic species characterisation and the identification of small area surface contaminants. The instrument design is unconventional, utilising a continuous primary beam and a pulsed secondary ion beam. This allows a high duty cycle in comparison with conventional ToF‐SIMS instruments (typically > 10% compared to < 0.1%), and also depth profiling with simultaneous continuous etching and ToF mass analysis. The use of such a spectrometer is thus ideally matched to the concept of a high‐throughput instrument with static, imaging and dynamic SIMS capabilities. The instrumental design is described and data presented to compare the practical performance of the quadrupole and ToF versions of the instrument. Copyright © 2006 John Wiley & Sons, Ltd.
Measured electron IMFPs for SiC
Authors: Krawczyk M. , Zommer L. , Kosiński A. , Sobczak J. W. , Jablonski A.
Published: March 2006

Silicon carbide (SiC) is a wideband semiconductor that is very promising for many applications in optoelectronics and microelectronics. Since information on the electron transport processes in SiC is scarce, its systematic study is highly desirable. The aim of this work is to determine experimentally by elastic peak electron spectroscopy (EPES), for the first time, the inelastic mean free paths (IMFPs) in bulk SiC with different structural properties (polycrystalline and monocrystalline materials) and surface concentrations of its constituents. The relative EPES measurements were carried out in the electron energy range 0.2–2.0 keV with two different analyzers (double‐pass cylindrical mirror analyzer (DCMA), spherical sector analyzer (SSA)) and the use of Ni standard. The measured IMFPs were uncorrected for surface excitations and compared with those calculated from the TPP‐2M and G‐1 predictive formulae using Fano plots. Good agreement was found between the measured and the calculated electron IMFPs in SiC exhibiting different structural properties. Copyright © 2006 John Wiley & Sons, Ltd.
Correlation between silicon‐nitride film stress and composition: XPS and SIMS analyses
Authors: Vanzetti L. , Barozzi M. , Giubertoni D. , Kompocholis C. , Bagolini A. , Bellutti P.
Published: March 2006

The characteristics of silicon‐nitride films deposited with plasma‐enhanced chemical vapour deposition (PECVD) can vary not only in composition, but also in terms of physical properties. An important parameter in the fabrication of micro‐electro‐mechanical systems (MEMS) devices is the control and tailoring of the film stress. In fact, silicon‐nitride film stress can vary from tensile (up to 800 MPa) to compressive (−500 MPa), depending on the PECVD deposition conditions (e.g. plasma pressure, plasma frequency and power).

In this work, we have investigated the role of frequency mixing on the resulting film structure and stress. The layers were prepared with a commercial PECVD deposition chamber, keeping all deposition parameters constant except the ratio between low (380 kHz) and high (13.56 MHz) frequency. Film stress values were compared with compositional and chemical data from X‐ray photoemission spectroscopy (XPS) and secondary ion mass spectrometry (SIMS) measurements. These two techniques are complementary.

The comparison between quantified SIMS depth profiles and the XPS HF etch‐back method shows a good agreement in nitrogen profile behaviour. In addition, XPS analyses have provided a suitable chemical characterisation of the different growth processes.

We demonstrate that this analytical approach is really effective for the physico‐chemical characterisation of PECVD grown silicon nitride. Copyright © 2006 John Wiley & Sons, Ltd.
Noble gas clusters in carbon nanopores
Authors: Krainyukova Nina V.
Published: March 2006

Low temperature high‐energy electron diffraction study of size‐dependent structures and growth mechanisms of neon and argon nanoclusters inside multiporous ‘amorphous’ carbon as well as theoretical consideration of cluster energetics with emphasis on shape optimization are presented. Multiply twinned particles (MTPs) such as icosahedra and decahedra (with fivefold symmetry) for small clusters are shown to be dominant. Applied analysis was based on the comparison of experimental and calculated intensities with the help of the R‐factor minimization procedure. The new method is applicable not only to structural studies of clusters grown in pores but also for pores characterization and can also be used in the analysis of the wide group of objects which undergo the growth typical of confined geometry. Copyright © 2006 John Wiley & Sons, Ltd.
Discrimination between γ′‐Fe4N and ε‐Fe2–3N iron nitride compounds using PCA of Auger electron spectra
Authors: Vandendael I. , Sloof W. G. , Steenhaut O. , Hubin A. , Vereecken J.
Published: March 2006

AES offers high spatial resolution that is useful when analysing cross sections of nitrided steels. To discriminate between different iron nitride compounds in such an analysis, so‐called factor analysis (FA) can be applied. This requires acquisition of Auger electron spectra which are associated with either the γ′‐Fe4N or the ε‐Fe2–3N phases as principal components. In this study, the N KLL and Fe LMM Auger electron spectral lines of γ′‐Fe4N and ε‐Fe2–3N phases were acquired in great detail from the pure γ′‐Fe4N and ε‐Fe2–3N phases obtained by gaseous nitriding of pure iron. To this end, two different samples of known composition were analysed. Firstly, Auger electron spectra were recorded from a nitrided layer with large γ′‐Fe4N grains (∼30 µm) on top of an iron substrate. Secondly, Auger electron spectra were recorded from an ε‐Fe2–3N outer layer (∼6 µm) with 26 at.% N, on a γ′‐Fe4N layer (∼4 µm) with 20 at.% N, created on top of an iron substrate. The latter sample was also used for FA. It is shown that principal component analysis of a series of N KLL Auger electron spectra recorded from the iron nitride double layer could be represented by three contributions. These principal components are associated with γ′‐Fe4N, ε‐Fe2–3N and the background. On the other hand, when a background subtraction was applied to the acquired N KLL Auger electron spectra, it was not possible to discriminate between the two iron nitride phases. Copyright © 2006 John Wiley & Sons, Ltd.
Characteristic analysis of electroless Ni plating layer for electronic packaging
Authors: Kim Dae‐Gon , Kim Jong‐Woong , Yoon Jeong‐Won , Lee Won‐Bae , Jung Seung‐Boo
Published: March 2006

The crystallization behavior of electroless Ni–P film was investigated using X‐ray diffractometry (XRD), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). XRD analyses revealed that the amorphous state of the as‐plated Ni–P film was crystallized by heat treatment at 573 K for 1 h. Two peaks were observed simultaneously, indicating Ni and Ni3P compounds. Convergent beam electron diffraction (CBED) pattern analyses confirmed a size of the Ni3P in the crystallized Ni–P layer of 50–70 nm. The contact resistance decreased with a heat treatment, which is mainly due to the crystallized Ni–P layer and the grain growth. The activation energy calculated from DSC analyses using the Kissinger equation was 195.2 kJ/mol. Copyright © 2006 John Wiley & Sons, Ltd.
Interfacial reaction during MOCVD growth revealed by in situ ARXPS
Authors: Brevet A. , Chassagnon R. , Imhoff L. , Marco de Lucas M. C. , Domenichini B. , Bourgeois S.
Published: March 2006

Angle‐resolved X‐ray photoelectron spectroscopy (ARXPS) experiments were performed to study in situ the reaction at the film–substrate interface during metal organic chemical vapor deposition (MOCVD) growth of TiO2 thin films deposited on the silicon substrate. The in‐depth distribution of chemical species was determined using several ARXPS thickness calculation models considering either single or bilayer systems. By the comparison of two single‐layer models, the presence of a second layer composed of silicon oxide was evidenced. High‐resolution transmission electron microscopy (HRTEM) observations confirmed the stratification of the film in two layers, as well as the perfect wetting of the surface by TiO2, irrespective of the model used. The contribution of the ARXPS bilayer model was demonstrated by the agreement of the values of film thickness obtained by both techniques. Nevertheless, the correlation between each layer's thickness was only possible by taking into account chemical species mixing. Indeed, the presence of oxidised silicon in the upper TiO2 layer, in addition to that of the SiOx interlayer, has to be considered to interpret ARXPS results in a correct way. Copyright © 2006 John Wiley & Sons, Ltd.
Computer program for the grain analysis of AFM images of nanoparticles placed on a rough surface
Authors: Chuklanov A. P. , Ziganshina S. A. , Bukharaev A. A.
Published: March 2006

Size is one of the most important characteristics of nanostructures and determines their properties. That is why it is very important to control the size and shape of these structures. Atomic force microscopy (AFM) is widely used to visualize 3‐D nanostructures, for example, nanoparticles placed on a surface. However, in many cases it is rather difficult to obtain accurate information about the size distribution of nanoparticles because of the complex structure of the substrate surface on which the particles are placed. Existing programs for grain detection and size distribution of nanoparticles are often not able to correctly process such AFM images of a surface. In this work, we propose to combine the existing methods for the grain detection and a priori information about shapes of nanoparticles. In particular, this allowed us to obtain better results in the grain analysis of sensors, which consisted of palladium nanoparticles grown on different substrates. Copyright © 2006 John Wiley & Sons, Ltd.
Fibronectin adsorption on Fe–Cr alloy studied by XPS
Authors: Galtayries A. , Warocquier‐Clérout R. , Nagel M.‐D. , Marcus P.
Published: March 2006

Improved knowledge of the chemical composition of biomaterial surfaces and a better understanding of interactions between biomolecules and material surfaces will allow a more rational design of biomaterials. Surface characterisation of alloys before and after their interaction with proteins is an essential aspect of this approach. In this work, the interactions of fibronectin with stainless steel surfaces (Fe–17Cr alloy) were studied by X‐ray photoelectron spectroscopy (XPS). Different solution concentrations of fibronectin were tested (0, 8, 60, 120 and 240 µg ml−1) in interaction with the stainless steel sample. N 1s, C 1s, Cr 2p and Fe 2p core level spectra were systematically recorded and compared. The results indicate that fibronectin is adsorbed on the stainless steel surface. The alloy surface composition and oxide thickness are almost unchanged (Fe2O3—Cr2O3 + Cr(OH)3) in presence of the protein, whatever the protein solution concentration. The isotherm of fibronectin adsorption at 37 °C was measured. A saturation is clearly reached for solution concentrations greater than 60 µg ml−1. On the plateau, the equivalent protein thickness is 6.3 nm, corresponding to one fibronectin monolayer. Copyright © 2006 John Wiley & Sons, Ltd.
Auger analysis and simulation of electronic states for Ge33As12Se55p‐Si heterojunction
Authors: Shchurova T. N. , Savchenko N. D. , Kondrat A. B. , Opachko I. I.
Published: March 2006

We present experimental data on Auger analysis of the amorphous Ge33As12Se55 filmp‐Si crystal heterojunction. The investigated depth profiles of the chemical components at the interface for the heterojunction revealed the presence of GeO2 and As2O3 from the film side and SiO2 from the crystal side in the interfacial region. The energy level diagram of the heterojunction was constructed on the basis of linear combination of atomic orbitals method and pseudopotential. Comparison of the results of simulation with experimental data shows applicability of the suggested theoretical approach to the computation of the energy band diagram of amorphous–crystalline heterojunctions taking into account the presence of electronic states at the interface. Copyright © 2006 John Wiley & Sons, Ltd.