bluuebunny/crossref_metadata_2025_split huggingface dataset:
Light Scattering Measurement Of Surface Topography During Formation Of Titanium Silicide.
Authors: Lavoie C. , Cabral C. , Clevenger L. A. , Harper J. M. E. , Jordan-Sweet J. , Saenger K. L. , Doany. F. 
Published: April 2011

AbstractThe evolution of the surface topography during the phase transformations of titanium silicide has been studied using elastic light scattering at two different collection angles. The light scattering measurements were performed simultaneously with x-ray diffraction and resistance measurements for titanium films deposited on either Si(100) or on poly-silicon substrates. At selected points during annealing, the samples were cooled rapidly to room temperature and analyzed ex situ using Nomarski microscopy. We find that, depending on the detection geometry, the in situ light scattering shows preferentially the formation of the C49 or C54 TiSi2 phase as well as differentiates between inversion and agglomeration on poly-silicon substrates.
Nano-scale Imaging of Corrosion: Application of Scanning Polarization Force Microscopy
Authors: Dai Qing , Hu Jun , Freedman Andrew , Robinson Gary N. , Salmeron Miquel 
Published: April 2011

AbstractScanning Polarization Force Microscopy, a recently developed non-contact imaging technique, is employed for the study of sulfuric acid induced aluminum corrosion. The morphological changes occurring during the corrosion of aluminum by sulfuric acid droplets were imaged in situ with nanometer resolution using Scanning Polarization Force Microscopy. The results of these experiments not only demonstrate the potential applications of SPFM in imaging liquid surfaces and weakly adsorbed species, they also offer new insights into the mechanisms of atmospheric corrosion.
Effect of Heavy Doping on the Photoluminescence and Photoreflectance Spectra of Silicon and SiGe Layers.
Authors: Bru-Chevallier C. , Trui B. , Souifi A. , Brémond G. , Guillot G. , Chroboczek J. A. 
Published: April 2011

AbstractPL and PR measurements have been performed on a set of silicon samples p-type doped between 1018 cm−3 and 1020 cm−3. Both optical methods are shown to be complementary as the bandgap narrowing effect is clearly evidenced from PL results, whereas low temperature PR results rather show the filling effect of the valence band, in good agreement with theoretical determinations. We observe an increase of E′0 transition as p-type doping level is increased.PR spectra of Si and SiGe alloys at low temperature are presented together with theoretical fitting using the third derivative functional form of the unperturbed dielectric function of both direct optical transitions involved in the main PR feature : E′0 and E1.This characterisation work will be discussed by pointing out that PL and PR results are closely connected, allowing the measurement of the effect of heavy doping on the Si and SiGe band structures.This study is fully relevant to high speed bipolar transistor development.
Monitoring Of Direct Reactions During Etching Of Silicon
Authors: Giapis K. P. , Minton T. K. 
Published: April 2011

AbstractWe present evidence of a direct reaction occurring when a hyperthermal fluorine atom beam (4.8 eV) impinges on a fluorinated silicon surface under steady-state etching conditions. When monitoring in-situ and in real time reactive scattering products by means of a quadrupole mass spectrometer, SiF3+ and SiF2+ are detected with bimodal time of flight distributions. The slow component can be described by a Maxwell-Boltzmann distribution at the surface temperature. However, the fast component is leaving the surface with velocities substantially higher than thermal and with a flux which does not obey the cosine law. Its translational energy increases with the angle of incidence of the hyperthermal fluorine beam. Etching in the direct reaction mode should result in highly anisotropic profiles by overcoming product desorption limitations.
Real-time Optical Monitoring of Epitaxial Growth Processes by p-Polarized Reflectance Spectroscopy
Authors: Dietz Nikolaus , Bachmannb Klaus J. 
Published: April 2011

AbstractIn this paper we introduce a real-time optical probe technique, p-polarized reflectance spectroscopy (PRS), for the monitoring of epitaxial growth processes. GaP heteroepitaxy by pulsed chemical beam epitaxy (PCBE) is used as an example. PRS allows to follow the deposition process with submonolayer resolution, utilizing a fine structure that is superimposed to the interference oscillations in the reflected intensity. This fine structure is explained by the periodic alteration of the surface reaction chemistry under pulsed chemical precursor supply. In the case of epitaxial GaP growth, it is modeled for a four layer stack, including an ultra-thin surface reaction layer of periodically changing thickness do(t) and dielectric function εo(t) tied to the periodic surface exposure to tertiarybutyl phosphine (TBP) and triethylgallium (TEG) pulses, respectively. The imaginary part of the dielectric function, εO2, of this surface reaction layer can be determined directly from the distance of the inflection points in the fine structure, where the optical response to the first precursor pulse in the cycle sequence changes sign, from the closests interference minimum. The surface reaction kinetics can be studied by analyzing the decay time characteristic in the transients of the fine structure.
Characterisation of the Oxidation Kinetics of Thin, Low Temperature, Electroless Plated Copper Films
Authors: Beechinor J. T. , O'Reilly M. , Patterson J. C. , Lynch S. , Lafferty E. , Kelly P. V. , Crean G. M. 
Published: April 2011

AbstractThe morphology, chemical state and oxidation behaviour of electroless copper films deposited from two different baths were characterised using scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), secondary ion mass spectrometry (SIMS) and spectroscopic ellipsometry (SE). The electroless solutions used were a commercial electroless formaldehyde (HCHO)-based solution (Cupro-Thick 84, Alfachimici) and an electroless solution developed within the NMRC which was based on dimethylamine borane (DMAB). Both methods produced as-deposited copper films with different morphologies. SE analysis of the as-deposited films and those oxidised in a dry synthetic air environment between 75°C–150°C indicated that the freshly deposited films had inherent oxide layers of between 45Å–92Å and that significant growth of these only occurred at temperatures above 100°C within 180 minutes isothermal oxidation periods. XRD analysis confirmed that the oxidation products formed were a mixture of cuprous oxide (Cu2O) and cupric oxide (CuO). Multiple linear regression analysis of the rates of change in oxide layer thicknesses as a function of both time and temperature indicated that mixed rate laws dominated. The application of an oxidation inhibitor was shown to prevent oxidation of the asdeposited commercial copper films when heat treated at 125°C.
Characterization of ZnSe:N Using Screening Effects
Authors: Kuskovsky I. , Neumark G. F. 
Published: April 2011

AbstractPhotoluminescence (PL) and Hall measurements allow one to obtain important parameters of semiconductors, such as impurity concentrations, compensation, and activation energies (EA). Usual analyses of such data assume constant EA. However, it is well known that EA depends on free carrier and impurity concentrations, and thus on temperature, due to screening effects. We here analyze literature data on ZnSe:N using screening effects. An observed decrease of EA with temperature (from PL data) had been used to suggest an interstitial site for N. With inclusion of screening, we obtained good agreement with the data, so that the idea of interstitial N is not required. In applying the screening theory to Hall measurements, we obtained lower impurity concentrations than with use of a constant EA. It is also to be noted that we fit both optical and electrical data with this approach. We further suggest that screening is the cause of an observed difference between optically observed and thermal activation energies.
Study of A+B-4C and A+2B–C Reaction-Diffusion System with Initially Separated Components
Authors: Yen Andrew , Kopelman Raoul 
Published: April 2011

ABSTRACTThe presence of a reaction front is a characteristic feature of a variety of physical, chemical and biological processes. The reaction exhibits a front, provided that the diffusing reactants are separated in space. We study the reaction front dynamics of both A+B→C bimolecular and A+2B→C termolecular reactions with initially separated components in a capillary. We measure and compare with theory and simulations the dynamic quantities that characterize the kinetic behavior of the system: the global reaction rate R(t), the location of the reaction center xf(t), the front's width w(t), and the local production rate R(xft). The non-classical nature of this dynamical system is confirmed.
A Model for the Two-Phase Behavior of Fluids in Dilute Porous Media
Authors: Donley James P. , Nyquist Rebecca M. , Liu Andrea J. 
Published: April 2011

ABSTRACTExperiments show that the coexistence region of a vapor-liquid system or binary liquid mixture is dramatically narrowed when the fluid is confined in a dilute porous medium such as a silica aerogel. We propose a simple model of the gel as a periodic array of cylindrical strands, and study the phase behavior of an Ising system confined in this geometry. Our results suggest that the coexistence region should widen out at lower temperatures, and that the narrowness observed near the critical point may be a fluctuation-induced effect.
Quasi-Elastic Neutron Scattering Study of the Fragile Glass-Former Salol
Authors: Toulouse J. , Pick R. , Dreyfus C. 
Published: April 2011

ABSTRACTQuasi-elastic neutron scattering (NS) measurements of Salol have been carried out in order to study the α and β relaxations near the liquid-glass transition. The results are presented in the form of a susceptibility spectrum that is compared with the corresponding spectrum obtained from light scattering (LS) and with the predictions from the Mode Coupling Theory. The differences between the NS and LS results are due to the different correlators contributing to the susceptibility in the two types of scattering. The possible origin of these differences are discussed in the framework of the Mode Coupling Theory.
Interaction of Organic Additives with Alumina Surfaces in a Ceramic Slurry
Authors: Sigmund W. M. , Wegner G. , Aldinger F. 
Published: April 2011

ABSTRACTThe interaction of organic additives with alumina surfaces was studied using a typical tape casting composition for alumina: solvent mixture trichloroethylene/ethanol, polyvinylbutyral (PVB) as binder and fish oil as dispersant.The characterization of the single components revealed why the dispersant Menhaden fish oil has such excellent dispersing properties for colloids and slurries. Menhaden fish oil used for wet-chemical processing was found to be a chemically polydisperse polymer with a dispersity of D=45 (by GPC) and a molecular weight of Mw=28,000.The investigation of the interaction in the highly concentrated colloidal slurry indicates that the high molecular weight fraction of fish oil is preferentially adsorbed and that an onion like supramolecular structure is formed by the ceramic particle/dispersant/binder system. The sequence in this nanostructure can be controlled by the sequence of addition of the compounds and is guided by polymer effects. The results gained on powders are supported by experimental data from surface plasmon resonance spectroscopy (SPR).
Saxs Characterization of Pyrolytic Carbon Blacks
Authors: Sahouli B. , Blacher S. , Brouers F. , Sobry R. , van den Bossche G. , Darmstadt H. , Roy C. 
Published: April 2011

ABSTRACTThe surface fractal dimension (Ds) of pyrolytic carbon blacks (CBp) was determined using small angle X-ray scattering (SAXS). The CBp were produced by vacuum pyrolysis of used tires at different temperatures and pressures. For the CBp a dependence of the pyrolysis conditions on the fractal dimension was observed. The fractal dimension decreases, suggesting a smother surface, with increasing pyrolysis pressure and to a lesser intent with increasing pyrolysis temperature. Earlier SIMS and ESCA investigations have indicated that an evident correlation exists between the surface morphology and the surface chemistry of the CBp. According to these investigations, the smoothing of the CBp surface is due to the formation of carbonaceous deposits from adsorbed hydrocarbons on the CBp.
Evolution of the Structure Factor in Gelling Dense Colloidal Silica
Authors: Muzny C. D. , Butler B. D. , Hanley H. J. M. 
Published: April 2011

ABSTRACTA solution of 30 % by mass, 7 nm diameter, colloidal silica spheres has been studied during gelation using small angle neutron scattering (SANS). A peak in the static structure factor appears early at a wavevector q ≈ 0.1 nm−1, and then grows in height and shifts to lower wavevectors as gelation proceeds. This is consistent with a cluster growth model in which this low-q peak in the structure factor indicates the presence of correlations between growing clusters. The peak continues to grow after the solution has visibly gelled indicating that the gel coarsens even after a stiff solid-like network has formed. The clear presence of cluster correlations at length scales only one order of magnitude larger than the particle size means that the usual fractal slope analyses are invalid in this system. We interpret the results by comparing the measured time evolution of the structure factor with computer simulations of Lennard-Jones particles quenched far below the critical line.
Low Loss Transmission Electron Spectroscopic Studies in Donor Doped BaTiO3
Authors: Katti Kalpana S. , Qian Maoxu , Sarikaya Mehmet 
Published: April 2011

ABSTRACTWe used the Kramers-Kronig transformation to investigate the local dielectric function of barium titanate, BaTiO3 from regions of sub-micrometer scale. Further the effect of dopants, in this case, Nb, on the dielectric function was investigated to assess the level of its local partitioning in the BaTiO3 lattice. The transmission electron energy loss spectroscopy technique was used to obtain dielectric function by placing a small electron probe in isolated regions of the electron transparent BaTiO3 samples. We observed an anomalous, but consistent, shift in the volume plasmon in all regions of the doped sample (compared to the pure one) indicating a uniform incorporation of the dopant within the lattice.
In-Plane Permittivity of Spin-Cast Polymer Films
Authors: Weinberg Shari A. , Bidstrup-Allen Sue Ann 
Published: April 2011

ABSTRACTPolymeric materials such as polyimides are used in a multitude of microelectronic applications including interlevel dielectrics for insulation. Polyimide films have shown a difference between the through-plane and in-plane refractive index measurements.(1,2,3) This anisotropy in optical properties has been attributed to in-plane orientation of polymer chains and implies anisotropy in electrical properties. Thus, it is necessary to measure the electrical properties in both the in-plane and through-plane directions to accurately design three-dimensional electronic packages. The purpose of this research is to develop an in-situ technique to measure the in-plane permittivity of these spin-coated polymer films. Using capacitance measurements obtained from interdigitated electrodes, through-plane permittivity measurements, and ANSYS finite element analysis software, the in-plane permittivity of a given material can be determined. Several polyimide systems including Du Pont PI-2611 (BPDA-PPD), Du Pont PI-2540 (PMDA-ODA), and Probimide 293 (BTDA-DAPI) from OCG Microelectronics, as well as Cyclotene 3022 (BCB) from Dow Chemical were investigated. Anisotropy in the permittivity was observed in the three polyimide films, but not in the BCB film. Results were compared with predictions using refractive index measurements and a modified form of Maxwell's equation.
Correlations Between Medium Frequency Blocking Parameters and Microstructure in Low Conductivity Materials
Authors: Kleitz M. , Dessemond L. , Steil M. C. , Thevenot F. 
Published: April 2011

ABSTRACTObservations have been made by impedance spectroscopy of various microstructure-induced blocking effects in cubic zirconias and composites. Correlations have been established between shape parameters of the microstructure defects and specific parameters of the electric response, such as the blocking factor and frequency factor, in the medium frequency range.Appropriate diagrams show the continuity and changes in the regimes of the microstructure evolutions.
Tunnelling in and The Microstructure of Granular Superconductors
Authors: McLachlan D. S. , Rosenbaum R. 
Published: April 2011

ABSTRACTThe microstructure of granular superconductors are discussed and the difference between granular and random composites is noted. The model where a granular (and a random) superconductor, close to the percolation threshold, is considered to be made up of large granular clusters, linked by tunnelling junctions or weak links, is introduced. This model is illustrated using recent experimental measurements on nanostructured granular Aℓ–Ge. The measurements clearly show that the coupling junctions between clusters can,depending on the volume fraction of superconductor, be of either a Josephson or quasi–particle nature, or a combination of both. The differences between a granular and adirty superconductor and the upper critical field of granular superconductors is then discussed and it is shown that the diameter of the grains can be estimated from the upper critical field. Random Aℓ–Ge, which has a rather different microstructure, is also discussed.
Correlation of Electrical, Dielectric And Mechanical Properties of Polymer Composites
Authors: Strümpler Ralf , Glatz-Reichenbach Joachim , Greuter Felix 
Published: April 2011

ABSTRACTThe electrical and dielectric response upon thermal expansion and contraction of polymer composites have been studied for thermoset polymers containing ceramic or metallic fillers. Before curing, the resistivity p of epoxy containing a metallic filler is in the range of 106 to 107 Ωcm. During curing a sudden reduction of p by eight orders of magnitude is observed. The shrinkage of the polymer during cross-linking and the build-up of internal stresses results in a lower interparticle contact resistance. The contraction can be reversed by heating. Around curing temperature, the resistivity increases by six to eight orders of magnitude due to the expansion of the material. The resistivity increases progressively until the percolation network of the conducting particles is interrupted and the composite reaches a high-ohmic state. Surprisingly, the critical temperature is related to the curing temperature and not to the glass transition temperature, as would be generally expected. Changes of the interparticle gap size can also be observed in the dielectric constant ε. For conducting fillers covered by a thin oxide layer, ε decreases by several orders of magnitude after a certain expansion has been achieved. However, for poorly conducting or insulating fillers dielectric response becomes insensitive to the gap distance. Hence, the electrical or dielectric response of polymers containing metallic fillers can be used as a sensitive probe for the internal stress state and the corresponding micro-structure of the composite.
Dielectric Spectroscopy of Nematic Liquid Crystal Confined in Random Porous Matrices
Authors: Aliev F. M. , Sinha G. P. 
Published: April 2011

ABSTRACTWe performed dielectric spectroscopy measurements to study dynamics of dielectrically active modes of nematic liquid crystals (LC) 5CB with polar molecules confined in silica porous glasses with average pore sizes of 1000 Å (volume fraction of pores 40%) and 100 Å (27%). In the nematic phase of bulk 5CB there is only one mechanism of dielectric relaxation: rotation of polar molecules around short molecular axis with relaxation time τ ∼10−8s. The spatial confinement and the existence of a highly developed interphase have a strong influence on dielectric properties of LC. We found that at temperatures about 30°C below the bulk melting point in both porous matrices the dielectric behavior of confined liquid crystal is very different from the behavior expected for solid state. The dielectric modes were not frozen in both porous matrices and we observed four well defined relaxational processes with relaxation times τ1 ∼ 10−1s, τ2 ∼10−5s, τ3 ∼10−8s (bulk like) and τ3 ∼10−9s. These four processes do not vanish even at temperatures corresponding to deep bulk isotropic phase. The relaxation time of the first process (slow) shows glass-like behavior in a wide temperature range below bulk melting point.
Phosphate-Sulfate Interaction in Simulated Low-level Radioactive Waste Glasses
Authors: Li H. , Darab J. G. , Matson D. W. , Smith P. A. , Hrma P. , Chen Y. , Liu J. 
Published: April 2011

AbstractUsing simulated low-level radioactive waste glasses, interaction between phosphate and sulfate in the glass network was systematically studied using Raman spectroscopy. Phosphate and sulfate interaction was shown to depend on the extent of saturation of both species in the glass. At elevated concentration level of phosphate and sulfate in combination, yet below the solubility limits, phosphate and sulfate both separated from the glass. In the 7-day product consistency test (PCT), the phase separated glasses were found to have higher normalized releases of sodium, phosphorous, sulfur, boron, and silicon than those of their baseline glasses without phase separation.
Dissolution of Basaltic Glass: Effects of pH and Organic Ligands
Authors: Teng Hui , Grandstaff D. E. 
Published: April 2011

AbstractDissolution of powdered glass from Kilauea volcano, Hawaii (ca 51% SiO2) was studied in a fluidized-bed, flow-through reactor at room temperature in both dilute HCI and organic ligand-bearing solutions (citrate and oxalate) to determine the effects of pH and organic acids on the dissolution rate. Dissolution was non-stoichiometric in both HCI and organic solutions; however, the relative release rates of various ions and the composition of leached layers or secondary phases are fimctions of pH and organic ligand concentration and type. In HCl solutions, the minimum glass dissolution rate, as assessed from the Na leaching rate, was 7.4 × 10−12 gm cm−2 sec−1, comparable with previous results, and was virtually independent of pH. Addition of citrate and oxalate increased the non-stoichiometry of dissolution. At pH 7, the overall rate of glass dissolution decreased (by as much as 5 times) at low ligand concentrations (< 1 mM), but increased by as much as five times at higher concentration (3 mM). High ligand concentrations do increase the release rate of some elements, especially multivalent cations, such as Fe3+ which form strong organic complexes, by as much as 100 times.