bluuebunny/crossref_metadata_2025_split huggingface dataset:
X‐ray photoelectron spectroscopy of alkali germanate glasses
Authors: Di Martino D. , Santos L. F. , Almeida R. M. , Montemor M. F. 
Published: October 2002

AbstractSeveral alkali germanate glasses of molar composition (100 − x)GeO2·xM2O (M = Na, with 0 ⩽ x ⩽ 35, or M = Cs, with 0 ⩽ x ⩽ 30) were prepared by melting, and their XPS spectra were recorded and analysed as a function of the alkali content. The simultaneous presence of bridging oxygen (BO) and non‐bridging oxygen (NBO) atoms was evaluated in both glass systems. In order to clarify the role of the alkali ions on the formation of NBO species, a series of different alkali germanate glasses were analysed (M = Na, K, Rb, Cs) for a particular glass composition 70GeO2·30M2O. This comparison revealed that the percentage of NBO atoms increased upon insertion of the heavier alkali ions. Some explanations are proposed to account for the ways in which the different alkali ions modify the structure of these germanate glasses, in connection with the so‐called germanate anomaly. Copyright © 2002 John Wiley & Sons, Ltd.
Surface and electrical studies of Fe–Si–B powders for soft magnetic applications
Authors: Godec M. , Mandrino Dj. , Šuštaršič B. , Jenko M. 
Published: October 2002

AbstractSoft magnetic composite (SMC) materials for soft magnetic applications were developed. The most important property of SMC materials, especially those used in a high‐frequency range, is that the soft magnetic powder particles are well insulated from each other. Alloy Fe–Si–B powders were prepared by water atomization. The surface of microcrystalline powders was heat treated in dry or wet hydrogen, chemically treated and investigated by AES and XPS. The electrical breakdown voltages of the powders and SMCs were measured. Copyright © 2002 John Wiley & Sons, Ltd.
Characterization of NiAl thin layers by AES and EXAFS
Authors: Mozetič M. , Zalar A. , Jagielski J. , Arčon I. , Panjan P. 
Published: October 2002

AbstractThe composition and structure of NiAl thin films prepared from Ni/Al were studied. Ni/Al Multilayers of Ni/Al were prepared by sputter deposition on well‐polished Si(111) substrates. The average composition was 50 at.% Ni and 50 at.% Al. In order to facilitate migration of particles between layers, two techniques were applied: thermal treatment in hydrogen plasma and ion beam mixing. The composition of the samples was determined by AES, and the structure by extended x‐ray absorption fine structure (EXAFS). In the case of thermal treatment, the periodicity of multilayers vanished at ∼800 K, but the structure remained similar to that of the untreated sample. In the case of ion beam mixing, however, the NiAl phase started growing at a temperature of ∼500 K. The concentration of NiAl phase reached ∼85% at ∼580 K and remained constant with further increase of the temperature during ion beam mixing. Copyright © 2002 John Wiley & Sons, Ltd.
Sensors from electrodeposited metal nanowires
Authors: Walter E. C. , Penner R. M. , Liu H. , Ng K. H. , Zach M. P. , Favier F. 
Published: October 2002

AbstractBased on their electronic conductivity behaviour, metallic nanowires may have analytical applications ranging from interconnects to sensors. We present in this paper an electrochemical method for synthesizing Mo and Pd metal nanowires ranging in diameter from a few tens of nanometres up to one micrometre, with millimetre lengths. Nanowires are prepared by the electrodeposition of metal at step edges present on a graphite surface. These nanowires can be used to connect metal nanoparticles (Ni, Au, etc.). Once transferred in a polymer cast, they can operate as sensors. We describe how these nanowires may be manipulated to make devices for analytical chemistry and, as an example of such nanodevice, a detailed overview of the characteristics of the first nanowire‐based sensor of hydrogen gas (H2) is given. Copyright © 2002 John Wiley & Sons, Ltd.
Study of ultrathin silicon oxide films by FTIR‐ATR and ARXPS after wet chemical cleaning processes
Authors: Rouchon D. , Rochat N. , Gustavo F. , Chabli A. , Renault O. , Besson P. 
Published: October 2002

AbstractThe narrowest feature on current integrated circuits is the gate oxide—the thin dielectric layer that forms the basis of field effect device structures. Silicon dioxide is the dielectric of choice and, if the present miniaturization trend continues, the projected oxide thickness will be <1 nm in 2005. Therefore, ultrathin silicon oxide layers using various preparation conditions have been studied by angle‐resolved x‐ray photoemission spectroscopy (ARXPS) and Fourier transform infrared attenuated total reflection (FTIR‐ATR).The silicon oxides obtained by wet chemical treatments such as RCA (SC1 + SC2), SC1 (standard clean), RHO3 (RCA + HF + O3) and DDC (diluted dynamic clean) are characterized in terms of chemical oxide quality before and after thermal annealing. The presence of suboxides (SiOx), as revealed by XPS results, is correlated with Ox–Si–H bonds observed by FTIR‐ATR. The FTIR‐ATR spectra, deconvoluted into four peaks in the asymmetrical stretching SiO bond region (1000–1200 cm−1), show differences between all these chemical oxides. The AS1 (in phase) and AS2 (out of phase) vibrations are compared in terms of position and intensity. The influence of thermal annealing on the chemical oxide quality is also presented. Copyright © 2002 John Wiley & Sons, Ltd.
SIMS depth profiling of ultrashallow P, Ge and As implants in Si using MCs2+ ions
Authors: Holliger P. , Laugier F. , Dupuy J. C. 
Published: October 2002

AbstractQuantitative determination of dose and junction depth in the source/drain region of future CMOS devices (typically 50 nm for the contact and 25 nm for the extension) requires SIMS instruments capable of measuring dopant profiles with high depth resolution and low detection limits. In this work we investigate the analytical usefulness of monitoring MCs2+ ions for semiconductor profiling of n‐type dopants such as P, Ge or As with a primary (Cs+ beam) impact energy of 1 keV on a SIMS Cameca IMS‐5f instrument. The results obtained on ultrashallow implants in Si and SiO2 indicate an improvement in the characterization by using the MCs2+ technique; this technique has the advantage over the MCs+ technique of providing higher useful yields for electronegative elements by up to 102 and can therefore be applied to perform more precise junction measurements in terms of concentration, dose, decay length and detection limit. Copyright © 2002 John Wiley & Sons, Ltd.
Composition and growth of anodic and thermal oxides on InP and GaAs
Authors: Pakes A. , Skeldon P. , Thompson G. E. , Hussey R. J. , Moisa S. , Sproule G. I. , Landheer D. , Graham M. J. 
Published: October 2002

AbstractResearch using surface analytical techniques (Auger, XPS and 16O/18O SIMS) to characterize anodic films (formed in aqueous electrolytes at ambient temperature) and thermal oxides (formed at ∼500°C) on both InP and GaAs is summarized. Anodic and thermal oxides on InP comprise an outer indium‐rich layer and an inner layer containing In2O3, phosphorus oxide and P–O compounds with indium. For anodic films, sequential 16O/18O SIMS experiments indicate oxygen ion ingress with inner layer growth at the film/substrate interface and outer layer growth of In2O3 at the film/electrolyte interface. Electrical measurements performed on metal–insulator–semiconductor (MIS) structures indicate the oxides on InP to be ‘leaky’. Thermal oxides formed on GaAs in oxygen consist primarily of Ga2O3 with a small amount of arsenic (a few per cent) at the outer oxide surface as both As2O3 and As2O5 and a significant accumulation of elemental arsenic at the oxide/substrate interface. This probably leads to a high density of electronic traps and poor electrical properties. Anodic oxides (∼40 nm thick) formed in phosphate solution, however, have better electrical properties exhibiting low current densities (up to 6 V), making these films potentially useful for device applications. Copyright © 2002 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.
Nano‐oxidation of titanium films with large atomically flat surfaces by means of voltage‐modulated scanning probe microscopy
Authors: Unal Kerem , Aronsson Björn‐Owe , Mugnier Yannick , Descouts Pierre 
Published: October 2002

AbstractTitanium films with large atomically flat surfaces were produced by adapting the template stripping method. The morphology of these surfaces was characterized by contact mode atomic force microscopy and a root‐mean‐square roughness of 0.23 nm at a 1 µm2 area was obtained. Sample bias voltage modulation was used for nanometer‐scale anodic oxidation of the Ti film. The oxide structures produced showed high reproducibility, with aspect ratios of 0.18 and 0.07 for voltage modulation and static pulse oxidation, respectively. The maximum height of oxide structures was found at ∼20 Hz voltage modulation frequency. Using a negative voltage on the sample in a combination with a Pt/Ir‐coated tip enhanced further the aspect ratio and increased the oxide structure height. The influence of control parameters on the aspect ratio of the oxide structures was studied. Copyright © 2002 John Wiley & Sons, Ltd.
Interaction of ultrathin nickel oxide films with single‐crystal zirconia and alumina surfaces
Authors: Sygellou L. , Zafeiratos S. , Tsud N. , Matolin V. , Kennou S. , Ladas S. 
Published: October 2002

AbstractThe behaviour upon thermal annealing of ultrathin nickel oxide films formed on yttria‐stabilized ZrO2(100) (YSZ) and α‐Al2O3(0001) (sapphire) by in situ oxidizing vapour‐deposited Ni films of 0.2–5 ML thickness, was investigated by XPS/x‐ray‐induced Auger electron spectroscopy (XAES). The sapphire substrate was also used following room‐temperature argon ion sputtering to create a defective surface. Heating the nickel oxide films in ultrahigh vacuum (UHV) leads to decomposition in a temperature range strongly dependent on the substrate. On YSZ, the oxide decomposes towards metallic Ni at ∼200 K lower temperature compared with sapphire, where the decomposition temperature is close to the estimated thermodynamic stability limit for nickel oxide in the UHV chamber (∼900 K). This result supports the previously conjectured substrate‐mediated nickel oxide decomposition on YSZ. Furthermore, upon oxide decomposition on sapphire, a chemical interaction with the substrate is evidenced, especially by XAES. This interaction, which appears to exist already at 580 K on the sputtered sapphire substrate, is attributed to the formation of an NiAl2O4 spinel‐like interfacial compound. Copyright © 2002 John Wiley & Sons, Ltd.
Interaction of NH3 with oxygen‐pretreated Ni at 600 K
Authors: Lescop B. , Fanjoux G. , Galtayries A. , Le Nadan A. 
Published: October 2002

AbstractThe aim of the present study was to investigate the reaction between ammonia and pre‐adsorbed oxygen on Ni at 600 K using metastable impact electron spectroscopy (MIES) and UPS techniques. For a given oxygen‐pretreated nickel surface, the changes in the MIES spectra along with ammonia adsorption can be decomposed into three different steps: a first domain without significant changes, a second domain corresponding to drastic changes in the intensity of a signal at 15.8 eV; and a third domain where no more change is detected. The first domain may correspond to the ammonia chemisorption on the surface, whereas the changes in the second domain would be attributed to surface dehydroxylation. The existence of NHx groups on the surface has been detected by UPS; they result from ammonia chemisorption. The changes in the MIES spectra have also been studied versus the initial oxygen uptake on Ni. It emerged that the first domain is larger with increasing initial oxygen exposure: this may be explained by the poorer surface reactivity of NiO, contrary to the oxygen‐adsorbed phase. Copyright © 2002 John Wiley & Sons, Ltd.
Surface chemical and electrokinetic characterizations of membranes containing different carriers by x‐ray photoelectron spectroscopy and streaming potential measurements: study of the effect of pH
Authors: Ariza M. J. , Rodríguez‐Castellón E. , Muñoz M. , Benavente J. 
Published: October 2002

AbstractTwo activated membranes containing 200 mM of di‐(2‐ethylhexyl) phosphoric acid (DEHPA‐2) and di‐(2‐ethylhexyl)dithiophosphoric acid (DTPA‐2) as carriers have been studied. The electrokinetic characterization of the membrane/solution interface was carried out by means of tangential streaming potential measurements, with the membranes in contact with an NaCl solution (5 × 10−4 M) at different pH (3.5 ≤ pH ≤ 8.5). These measurements allow the determination of the zeta potential, the electrokinetic surface charge density and the isoelectric point of the membranes. Other membrane characteristic parameters such as the acidic dissociation constant or the number of acidic sites per membrane area (density of acidic sites) can be determined if a site dissociation model is used. On the other hand, chemical changes in the membrane surfaces due to contact with solutions at different pH were determined by comparing XPS spectra of the used samples with the original ones. In order to see the influence of each type of carrier on electrokinetic parameters, a comparison with the polymeric base membrane (B0) has also been made. Copyright © 2002 John Wiley & Sons, Ltd.
Characterization of hydrogen gas diffusion electrodes for reduction of metal from industrial process liquids
Authors: Schulze M. , Lorenz M. , Wagner N. 
Published: October 2002

AbstractGas diffusion electrodes can be operated in a lot of electrochemical processes and devices, such as fuel cells, electrolysis and cleaning of waste water from electrochemical treatments of metals (electrochemical machining, electrochemical drilling and galvanic processes). Carbon black‐supported platinum is mixed with polytetrafluoroethylene (PTFE) in a knife mill and rolled onto a metal web to form an electrode. The electrodes were characterized before and after electrochemical operation with x‐ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Induced by the rolling process of the PTFE–carbon black powder, the PTFE forms thin fibres that are spun to a web in the electrode.The surface composition of the electrodes for electrochemical metal treatment and cleaning of galvanic waste water changes during the operation time. Owing to the presence of metal ions in the liquid electrolyte in these applications, metal is deposited onto the electrode surface during the operation time. Depth profiling of the electrodes shows that metal is not only deposited on the surface but also in the electrodes. Copyright © 2002 John Wiley & Sons, Ltd.
Optical characterization of thin films non‐uniform in thickness by a multiple‐wavelength reflectance method
Authors: Ohlídal M. , Ohlídal I. , Franta D. , Králík T. , Jákl M. , Eliáš M. 
Published: October 2002

AbstractAn original method enabling us to characterize the non‐uniformity of thin‐film thickness is described. This method employs the interpretation of data obtained by multiple‐wavelength reflectometry (MWR). Within this MWR method the values of the reflectance are measured for several wavelengths in many points lying along the area of the film. The spectral dependence of the refractive index of the material forming the film is determined using variable‐angle spectroscopic ellipsometry (VASE). The MWR method is then used to evaluate the values of the thickness along the area of the non‐uniform film under investigation. Within the experimental set‐up employed for applying the MWR method, a multi‐wavelength laser is used as a light source. A CCD camera equipped with a zoom objective is utilized as a detector. A suitable beamsplitter allows to measure the values of the relative reflectance of the film against a reference sample with known reflectance. By using the set‐up employed it is possible to characterize the thin‐film spreading over large areas of substrates. Copyright © 2002 John Wiley & Sons, Ltd.
Study of Zr1−xSnxTiO4 thin films prepared by a polymeric precursor route
Authors: Gusmano G. , Bianco A. , Viticoli M. , Kaciulis S. , Mattogno G. , Pandolfi L. 
Published: October 2002

AbstractZirconium–stannate titanate Zr1−xSnxTiO4 (ZTS) thin films, undoped and doped with Sb, Ta and Nb, were prepared by a polymeric precursor technique. The ZTS films were deposited on the multilayered substrates (Pt/Ti/SiO2/Si) by means of multiple spin‐coating. After this deposition, the samples were heated at different temperatures (300–700°C). The chemical composition of these films and bulk ZTS samples was investigated by using x‐ray photoelectron spectroscopy and selected‐area XPS depth profiling. A partial surface segregation of SnIV and the presence of Sn0, TiII and TiIII species in the films were revealed from XPS depth profiles. An optimized ZTS deposition process, where an oxidizing agent (H2O2) is added to the gel, is proposed. Copyright © 2002 John Wiley & Sons, Ltd.
V2O5 thin films deposited by means of d.c. magnetron sputtering from ceramic V2O3 targets
Authors: Poelman H. , Tomaszewski H. , Poelman D. , Fiermans L. , De Gryse R. , Reyniers M.‐F. , Marin G. B. 
Published: October 2002

AbstractThe deposition of stoichiometric V2O5 films for abrasion‐resistant V2O5/TiO2 anatase catalysts was investigated. Direct current magnetron sputtering from ceramic oxide targets in an argon/oxygen atmosphere was chosen as the deposition technique. Layers were prepared with different oxygen mole fractions in the plasma and the influence upon electronic and optical properties was investigated. Surface XPS measurements showed that stoichiometric layers are obtained for low oxygen flows, whereas for higher oxygen contributions reduced vanadium species are increasingly present. This departure from stoichiometry is ascribed to active re‐sputtering of the deposited layer by O− ions, due to the higher sputter yield of oxygen compared with vanadium. Polycrystalline V2O5 layers were obtained at elevated substrate temperatures. Optical absorption coefficients in the visible region were found to correlate well with the layer stoichiometry, as deduced from the XPS lineshape analysis. Copyright © 2002 John Wiley & Sons, Ltd.
Work of adhesion and fretting: influence of material surface properties and medium
Authors: Lambert Mathieu , Duluc Sébastien , Paris Jean‐Yves , Baziard Yves , Denape Jean 
Published: October 2002

AbstractThis work attempts to link tribological and adhesion phenomena in fretting conditions. Fretting experiments were carried out in three environmental conditions (air atmosphere, demineralized water and kerosene) and with various couples of industrial materials. Contacting materials and liquids were chosen mainly for their surface properties, in order to have a wide range of surface free energies. The fretting device included a pin‐on‐plane configuration. The pin (or slider) was fixed and the plane was the moving substrate. The total distance (dT) covered by the moving substrate was chosen as the tribological parameter representative of the history of an experiment. The distance dT was then compared to surface parameters such as Dupré's work of adhesion between the two substrates in contact (W12) and with three bodies (W132), the index 3 being the liquid medium. In these conditions, dT = f(W12) and dT = f(W132) variations were found to be linear, thus showing a clear link between friction and adhesion. Copyright © 2002 John Wiley & Sons, Ltd.
Clinical research and trials in developing countries
Authors: Yusuf Salim 
Published: October 2002

AbstractOver 80 per cent of the global disease burden occurs in developing countries. Yet the proportion of research conducted in these countries is less than 10 per cent of the global research activity. This article emphasizes the need to conduct research in developing countries on locally relevant questions, provides general principles that may assist in establishing such studies, and describes some experiences in the cardiovascular area. Copyright © 2002 John Wiley & Sons, Ltd.
Cytotoxic effects of triphenylbismuth on rat thymocytes: Comparisons with bismuth chloride and triphenyltin chloride
Authors: Arata Tomohiro , Oyama Yasuo , Tabaru Ken , Satoh Masaya , Hayashi Hiromi , Ishida Shiro , Okano Yoshiro 
Published: October 2002

AbstractThe biomedical and industrial uses of organobismuth compounds have become widespread, although there is limited information concerning their cytotoxicity. Therefore, the actions of triphenylbismuth on rat thymocytes were examined using a flow cytometer with ethidium bromide, annexin V‐FITC, fluo‐3‐AM, and 5‐chloromethylfluorescein (5CMF) diacetate. Triphenylbismuth at 3–30 μM increased the population of cells stained with ethidium, indicating a decrease in cell viability. Organobismuth at 30 μM increased the population of cells positive to annexin V, suggesting an increase in the population of apoptotic cells. Triphenylbismuth at 3 μM or more decreased cellular glutathione content (5CMF fluorescence intensity) and increased intracellular Ca2+ concentration ([Ca2+]i, fluo‐3 fluorescence intensity) in a dose‐dependent manner. Because an increase in [Ca2+]i is linked to cell death or cell injury and a decrease in cellular glutathione content increases cell vulnerability to oxidative stress, the triphenylbismuth‐induced changes in cellular parameters may be responsible for triphenylbismuth‐induced cytotoxicity. Bismuth chloride at 10–30 μM did not significantly affect cell viability. These results suggest that triphenylbismuth at micromolar concentrations exerts cytotoxic action on rat thymocytes, possibly related to a health hazard. Although the cytotoxicity of triphenylbismuth was less than that of triphenyltin, one of the environmental pollutants, it is necessary to direct our attention to the use and disposal of organobismuth compounds. © 2002 Wiley Periodicals, Inc. Environ Toxicol 17: 472–477, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/tox.10081
Recording a line profile across ion‐implanted conductor paths in Si wafers by a synchrotron beam microprobe
Authors: Klockenkämper R. , von Bohlen A. , Radke M. , Knöchel A. , Palmetshofer L. 
Published: October 2002

AbstractSynchrotron radiation was applied to recording a line profile across buried conductive paths in a silicon 〈100〉 wafer. For that purpose, Co ions were first implanted in a depth of 60 nm below the silicon surface with a dose of 1017 cm−2 and an energy of 100 keV. By means of a photoresist mask, small strips of ca 150 and 40 µm width were produced. The analytical characterization was performed at DESY/HASYLAB by concentrating the synchrotron beam with a cylindrical and a tapered capillary with an effective diameter of 10 and 4 µm, respectively. The implanted wafer was shifted in steps of 1 µm on a straight line along a capillary in order to record a line profile of the implanted element cobalt across the buried strips. An internal standard was used in order to compensate for the large long‐term drift and the strong fluctuations of the synchrotron beam. A 0.1 µm thin Ti foil turned out to be a very simple standard easily placed in front of the implanted wafer. This aid facilitates an examination of buried layers with a flank down to only micrometer steepness and with a uniform plateau down to only 1% deviations. Copyright © 2002 John Wiley & Sons, Ltd.