bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nmr Studies of Electronic and Local Structure in Cu-Au Alloys
Authors: Chepin James , Ross Joseph H. 
Published: April 2011

ABSTRACTWe have studied ordered and disordered Cu-Au alloys via 63Cu NMR, probing local electronic structure in the bulk and near anti-phase boundaries in CuAuII. A line-shape model has provided good agreement for disordered and partially ordered alloys, and we thus have obtained a measure of local site symmetries, and Knight shifts and local densities of states within the alloys. We have combined Knight shift and relaxation measurements to obtain detailed local information. We report effects of the ordering process in Cu3Au, CuAu, and CuAu3 intermetallics. We find enhanced susceptibility at the CuAuII anti-phase boundary which is heavily anti-site populated. We compare these results to other measurements of these properties.
The Field Emission Gun Scanning Electron Microscopehigh Resolution at Low Beam Energies
Authors: Joy David C 
Published: April 2011

ABSTRACTThe scanning electron microscope (SEM) is the most widely used, as well as the most versatile, of electron-optical instruments. In all of the imaging modes of the instrument it is now possible to achieve a spatial resolution on the nanometer scale from a bulk specimen, provided that the electron-optical performance of the instrument is of the necessary quality. In practice this means that a field emission gun (FEG) as well as a highly excited probe forming lens must be used. With state-of-the-art instrumentation, image resolutions as good as 4 - 5 nm at lkeV, and lnm at 20keV, are now achievable. This paper outlines the design criteria for a high resolution FEG SEM and discusses the type of image information available. The performance achieved is compared to that of other types of microscope that offer similar capabilities.
Atom Probe Microscopy and its Future
Authors: Kelly T. F. , Camus P. P. , Larson D. J. , Holzman L. M. 
Published: April 2011

ABSTRACTMuch of the current activity and excitement in materials science involves processing and understanding materials at the atomic scale. Accordingly, it is necessary for materials scientists to control and characterize materials at the atomic level. There are only a few microscopies that are capable of providing information about the structure of materials at the atomic level: the atom probe field ion microscope, the high resolution transmission electron microscope, and the scanning tunneling microscope. The three-dimensional atom probe (3DAP) determines the 3D location and elemental identity of each atom in a sample. It is the only technique that provides 3D information at the atomic scale.The origin and underlying concepts behind the 3DAP are described. Several examples of actual images from existing 3DAPs are shown with emphasis on nanometer-scale analysis. Current limitations of the technique and expected future developments in this form of microscopy are described. It is our opinion that 3D atomic-scale imaging will be an indispensable tool in materials science in the coming decades.
Determination of the Mechanical Behaviour of Thin Films on Substrate Systems from Micromechanical Experiments
Authors: Ignat M. , Scafidi P. , Duloisy E. , Dijon J. 
Published: April 2011

ABSTRACTMicromechanical tensile experiments in a Scanning Electron Microscope (SEM) allowed us to identify and follow the activation of a variety of different deformation mechanisms, on several sorts of films on substrate systems. The investigated systems consisted of SiO2 and YF3 films deposited on copper and aluminium substrates, with or without an interlayer. The experimental results show that the mechanical response of the films differs, in particular, with respect to the interface response: the cracking activity will depend on the film adhesion. An attempt is made to relate the microstructural parameters of the assembled materials with the observed mechanisms, through models which are based on the shear lag formalism. Critical parameters of the systems under stress are determined and compared to theoretical calculations: critical stresses and strains for cracking, stress transfer lengths, interfacial fracture energies. The approach gives some insights on the mechanical response of films on substrate systems submitted to a tensile state of stress.
The Effect of Ultra-Low Temperature Treatments on the Stress in Aluminum Metallization on Silicon Wafers
Authors: Baldwin Frank , Holloway Paul H. , Bordelon Mark , Watkins Thomas R. 
Published: April 2011

ABSTRACTThe stresses in Al-0.75w%Si-0.5w%Cu unpatterned metallization on silicon wafers have been measured using substrate curvature and x-ray diffraction techniques after quenching in liquid nitrogen. Stresses were measured with and without phospho-silicate glass overlayers and SiO2 underlayers, and thermal cycling followed by relaxation at room temperature. It was found that cooling the substrates to 77 K and warming to room temperature caused the metallization stress to go from tensile to compressive. Subsequent heating of the substrates to above ∼70°C followed by cooling to room temperature caused the stress to become tensile. Both compressive and tensile stresses were found to relax at room temperature with a time constant of 2.3 ± 0.2 hours. The magnitude of stress relaxation was a function of temperature, being about 20 MPa after heating to 240°C. The metallization exhibited both compressive and tensile flow stresses of ∼100 MPa near room temperature.
Transgranular Slits in Aluminum Interconnects Caused by Thermal Stress and Electric Current
Authors: Wang W. , Suo Z. , Hao T.-H. 
Published: April 2011

ABSTRACTAn aluminum interconnect can fail by a transgranular slit. We show how a rounded void collapses to such a slit, as atoms diffuse on the void surface, driven by electric current, thermal stress, and surface energy. We use a variational principle to simulate the shape evolution, and identify the critical conditions to trigger the shape instability.
Cracking Mechanisms of Fine Lines by Microwedge Scratch Testing
Authors: Boer M. P. dE , Huang H. , Nelson J. C. , Lilleodden E. T. , Gerberich W. W. 
Published: April 2011

ABSTRACTThree types of cracks associated with interfacial failure of a tungsten fine line on silicon oxide (SiO2) have been observed in microwedge scratch testing (MWST) of fine lines. They were identified by carefully controlling scratch conditions in a continuous microindenter system1, in conjunction with SEM micrographs. The first type is a hinge crack, which is responsible for nucleating an interfacial crack. The driving force for the hinge crack is the difference in stress conditions in the middle on theline (plane strain) and the outside of the line (plane stress). The second type is the interfacial crack, which is driven by the movement of the microwedge. This crack is modelled by the finite element method (FEM) to obtain an interfacial work of adhesion value. The third type of crack is a spallation crack, and is driven by tensile strains associated with buckling of the thin film once the interfacial crack becomes sufficiently long. Tensile strains in the film at the maximum crack length are calculated by FEM in order to arrive at a value of thin film fracture strength. A brittle failure mechanism has beenconfirmed by a micrograph of a spalled piece exhibiting no perceptible plastic deformation.
Atomic Force Microscopy Structural Characterization of Polyaniline Thin Film Sensors
Authors: Josefowicz Jack Y. , Yamagishi Frederick G. , Ast Camille I. van 
Published: April 2011

ABSTRACTUsing Tapping Mode Atomic Force Microscopy (TMAFM), the surface structure was determinedfor polymer sensors which incorporated polyaniline (PAn) films that were deposited electrochemically across narrow insulating gaps between interdigitated gold electrodes. The sensitivity and response time for such sensors, which can be used for the detection of low levels of gases and low concentrations of impurities in liquid media critically dependon the quality and structure of the polymer film in the gap region between the gold electrodes. TMAFM images of the PAn films ranging in thickness between ≈1.5μtmand ≈5μm reveal that films approaching 5μm (typically used in such sensors) develop deep cracks at the edges and along the length of the Au electrodes. Thecracks, which appear to be a consequence of stress build-up in thick films, can lead to reliability problems and inferior sensor performance. Simple modeling analysis of cracked films indicates that they can lower sensitivity and increase response time. TMAFM images of sensors with thinner ≈2.5μm PAn films show no cracks as well as continuous PAn bridges across the gap between Au electrodes. Analyses of TMAFM images are presented and compared for thin and thick film PAn sensors.
Embedded Circuitry in Polymeric Films by Linear Energy Transfer (Let) of MeV Ions
Authors: Ila D. , Evelyn A. L. , Qian Y. 
Published: April 2011

ABSTRACTWe have developed a technique to fabricate embedded variable conductivity paths in phenolformaldehyde, PF-resin, with resistivity as high as 109 Ω-cm. The resin used for this work consists of a monomer called Phenyl Methanol (Resol) which upon setting at 150ºC will form short chains of polymers with high resistivity. The conductive paths are produced at depths of 4 to 35 micrometers by changing the energy of thebombarding ions. The resistivity of each path is controlled between 109 Ω-cm to 10 Ω-cm by adjusting the ion dose. The ions used in this work are nitrogen, alphas and protons with energies between 0.5 and 6.5 MeV to form conductive paths as narrow as 0.5 mm and as wide as 4 mm.
Atomic Scale Structure and Chemistry of Interfaces by Z-Contrast Imaging and Electron Energy Loss Spectroscopy in the Stem
Authors: McGibbon M. M. , Browning N. D. , Chisholm M. F. , McGibbon A. J. , Pennycook S. J. , Ravikumar V. , Dravid V. P. 
Published: April 2011

AbstractThe macroscopic properties of many materials are controlled by the structure and chemistry at grain boundaries. A basic understanding of the structure-property relationship requires a technique which probes both composition and chemical bonding on an atomic scale. High-resolution Z-contrast imaging in the scanning transmission electron microscope (STEM) forms an incoherent image in which changes in atomic structure and composition across an interface can be interpreted directly without the need for preconceived atomic structure models (1). Since the Z-contrast image is formed by electrons scattered through high angles, parallel detection electron energy loss spectroscopy (PEELS) can be used simultaneously to provide complementary chemical information on an atomic scale (2). The fine structure in the PEEL spectra can be used to investigate the local electronic structure and the nature of the bonding across the interface (3). In this paper we use the complimentary techniques of high resolution Zcontrast imaging and PEELS to investigate the atomic structure and chemistry of a 25° symmetric tilt boundary in a bicrystal of the electroceramic SrTiO3.
Crystallization of Epitaxial Lanthanum Aluminate and Spinel Thin Films Derived from Nitrate Precursors
Authors: Ng Man Fai , Cima Michael J. 
Published: April 2011

AbstractBoth lanthanum aluminate (LaAIO 3) and spinel (MgAl2O 4) epitaxial thin films have been deposited on either planar and stepped (100) SrTiO3 single crystal substrates by pyrolysis of mixed nitrate precursors. The precursors pyrolyze initially into amorphous films. Nucleation of lanthanum aluminate and spinel occurs at the filnVsubstrate interface at higher temperature. Crystallization of LaAlO3 on SrTiO3 substrates occurs at approximately 650°C, whereas nucleation occurs at approximately 800'C without lattice-matched substrates. Similarly, latticematched substrates reduce the crystallization temperature of spinel to below 700°C. The epitaxial film grows at the expense of the amorphous film after the initial nucleation at the interface. The rapid growth and volume change due to the crystallization leave behind an epitaxial film with nanoporosity of 15 to 30 nm. Nevertheless, the surfaces of these films have roughness of only 6–9 Å. Ba2Ycu3O7-x films derived from metalorganic deposition of metal trifluoroacetate precursors was deposited on these epitaxial LaAlO3 films on both planar and stepped SrTiO3 substrates. The resultant YBCO films on LaAlO3 film on planar SrTiO3 substrate have critical current densities of > 2 × 106 A/cm2 at 77K and zero field.
Epitaxial Dielectric Planarization for Multilayer HTSC Structures
Authors: Chang Bertha P. , Mcintyre Paul C. , Sonnenberg Neville , Cima Michael J. 
Published: April 2011

AbstractYttria-stabilized ZrO2 (YSZ) and CeO2 thin films were deposited on patterned (001) YSZ and (001) LaAIO3 substrates, respectively, using ion beam assisted deposition (IBAD) at normal incidence and an ion beam energy of 500eV. All deposition took place at 600°C. An initial 1000Å thick layer was evaporated at 0.2Å/s before beginning IBAD at rates of 0.3Å/s for YSZ and between 0.8Å/s and 1.2Å/s for CeO2. X-ray diffraction shows the YSZ films to grow epitaxially. The planarization mechanism for IBAD YSZ is similar to that previously observed for if-bias sputtering. CeO2 grows epitaxially on LaA103 but a second polycrystalline phase grows preferentially over the surface steps and inhibits the planarization process. The emergence of this phase appears to be related to highly incoherent growth of CeO2 over the stepped edges, which in turn is a function of the large lattice mismatch between CeO2 and LaA1O3 in the [001] direction.
Properties of Iron Oxide Films Grown by Pulsed Laser Deposition
Authors: Choi H. S. , Ahn J. S. , Jo William , Noh T. W. , Chun S. H. , Khim Z. G. 
Published: April 2011

AbstractEpitaxial magnetite (Fe3O4) thin films have been grown on MgO(001) substrates by pulsed laser deposition. The films have characteristics of the “Verwey transition”: the electric conductivity decreases by about one order of magnitude and the magnetization curve shows anomaly at the transition temperature, i.e. about 125 K. Effects of annealing the Fe3O4 thin films at various oxygen partial pressures have also been investigated. Phase identification was made using XRD techniques and infrared reflectivity measurements. The surface morphologies were studied by SEM and AFM. Under an oxidizing atmosphere, the Fe3O4 phase is transformed mainly into α-Fe2O3, and this transformation is accompanied by development of needle-like structures along <110> directions of MgO substrate. It is also found that electrical and magnetic properties of the iron oxide films are changed significantly by the annealing process.
Deposition of Monolayer-Scale Germanium/Silicon Heterostructures by Rapid Thermal Chemical Vapor Deposition
Authors: Amour A. St. , Sturm J.C. 
Published: April 2011

ABSTRACTDeposition of monolayer scale Ge/Si heterostructures by Rapid Thermal Chemical Vapor Deposition has been achieved for the first time. All previous work in this area was by Molecular Beam Epitaxy. We have observed the change in Ge growth rate at 500°C as the Si substrate was covered by the first monolayer of Ge. Auger Electron Spectroscopy and Raman scattering experiments determined that the CVD growth mode for Ge on Si (100) at 550°C is Stranski-Krastanov, with the transition to islanding occurring after three monolayers.
Rapid Thermal Annealing of Low-Energy P and B Implants in Silicon, Optimized by High Resolution X-Ray Diffraction
Authors: Klappe Jos G.E. , Bársony István , Woerlee Pierre H. , Ryan Tom W. , Alkemade P. 
Published: April 2011

ABSTRACTIn this paper, low-energy (45 keV) implantations of phosphorous and boron into silicon were studied. A comparison of doping profiles, secondary defect formation, electrical activation and diode leakage was made between Rapid Thermal Annealing (RTA) and conventional furnace annealing. The samples were analysed by High-Resolution X-Ray Diffraction (HR-XRD), X-TEM, SIMS, spreading resistance (SRP) and sheet resistance measurements.The non-destructive HR-XRD technique combined with the novel simulation software was a very useful tool for the defect characterisation and for the choice of the optimum annealing temperature. Furthermore estimations of electrically active dopant atoms were made with HR-XRD by measurement of the strain. With RTA a substitutional dopant concentration of a factor 2 to 4 higher than with furnace annealing can be obtained, for P and B respectively. Electrical measurements show that not all of the substitutional dopants are electrically active, however. Thus estimates of the electrically active dopant atoms with HR-XRD require further study. Furthermore it appeared that RTA was superior to furnace anneal for lowering sheet resistances, defect removal and dopant profile broadening. However, furnace anneal gave the best results for diode leakage currents. This indicates that RTA processing needs to be further refined or that combined RTA/furnace processes need to be developed.
Boron Doping using Proximity Rapid Thermal Diffusion from Spin-on-Dopants
Authors: Rastogi M. , Zagozdzon-Wosik W. , Romero-Borja F. , Heddleson J. M. , Beavers R. , Grabiec P. , Wood L. T. 
Published: April 2011

ABSTRACTProximity rapid thermal diffusion (RTD) has been investigated as a doping technique for p-type boron doped junctions. The efficiency of RTD has been studied as a function of process variables (temperature, time, and ambient) and evaluated based on sheet resistance measurements, secondary ion mass spectroscopy (SIMS), spreading resistance (SR), and Fourier transmission infrared absorption (FTIR) in a spin-on-dopant source (SOD). The doping efficiency in source wafers is controlled by different mechanism than in processed wafers. Strong influence of dopant incorporation in the processed wafers on oxygen content in the diffusion ambient is observed especially at low diffusion temperatures.
A 3-Dimensional Temperature Uniformity Model for a Rapid Thermal Processing Furnace
Authors: Henda R. , Scheid E. , Bielle-Daspet D. 
Published: April 2011

ABSTRACTA fully three dimensional model has been developed for simulating the thermal behaviour of a RTP furnace. This model consists of two components to achieve the whole analysis. The first component models the radiation heat flux density at the wafer surface as a function of the system geometry, the lamp position and intensity, and the wall reflectivities. The second component solves the heat conduction equation at each point within the wafer using appropriate boundary conditions, including convective cooling which effect depends on the process conditions. A particular attempt is made upon the achievement of a flat temperature profile over the wafer by investigating the system parameters in order to improve the RTP equipement.
Temperature dependent Emissivity Measurements of Si, SiO2/Si, and HgCdTe
Authors: Ravindra N.M. , Tong F.M. , Kosonocky W.F. , Markham J.R. , Liu S. , Kinsella K. 
Published: April 2011

ABSTRACTThe results of emissivity of (a) Si and SiO2 /Si in the temperature range of 320 to 1240 K and (b). HgCdTe at temperatures of 303 and 440 K, using Fourier Transform Infrared(FTIR) spectroscopy, in the wavelength range of 1.5 to 20 μm, have been reported here. The measurements on SiO2 /Si have been performed for oxide thickness ranging from 60 to 500 nm. These results coufled with calculations of emissivity from first principles lead us to model the wavelength dependence of emissivity. Emissivity estimates have been obtained for HgCdTe using its fundamental optical constants.
Recent Pollution Prevention Research In III-V Device Manufacturing At Hewlett-Packard
Authors: Shire Douglas B. 
Published: April 2011

AbstractSeveral coordinated hazardous waste minimization projects have been undertaken at our facilities involved in III-V device manufacturing. These include modifications to existing processes to reduce or eliminate emissions of CFCs, 1,1,1-TCA, xylenes, ethylene glycol ethers, 1,2,4-trichlorobenzene (in photoresist stripper), and other compounds. These issues are addressed in turn, noting the unique aspects of GaAs and GaP device manufacture that need to be taken into account. Goals achieved have been complete cessation of CFC and 1,1,1-TCA use and 33% reductions in xylene and 1,2,4-trichlorobenzene usage since 1990, despite significant increases in total production volume during the same time period. Specific strategies are also described for tracking chemical use and sharing best practices for hazardous waste reduction across functional groups.
Reactive Ion Etch of GaAs and AIGaAs Using BCl3, SiCl4 and SF6.Instead of CCl2F2
Authors: Wu J. W. , Chang C. Y. , Lin K. C. , Chang E. Y. , Hwang J. H. 
Published: April 2011

AbstractIn the past, CCl2F2 had been widely used in the dry etching process of the GaAs-based materials, However, it causes ozone depletion and is detrimental to the environment. In order to prevent further ozone depletion, it is necessary to search for some substitutedl gases. In this study, chloric gases, like BCl3 and SiCl4, were used to provide an alternative way for the reactive ion etch of GaAs and AlGaAs. To provide high etching selectivity between GaAs and AlGaAs, a fluorine containing gas SF6 is added, to increase the etch rate of GaAs than that of AlGaAs, which is due to the formation of non-volatile solid AlF3. In this study the etching characteristics of the BCl3/SF6, SiCl4/SF6 were studied and high etching selectivity between AlGaAs/GaAs is achieved.
Environmental Applications of Xanes: Speciation of Tc In Cement After Chemical Treatment and Se After Bacterial Uptake
Authors: Shuh D. K. , Kaltsoyannis N. , Bucher J. J. , Edelstein N. M. , Clark S. B. , Nitsche H. , Almahamid I. , Torretto P. , Lukens W. , Roberts K. , Yee B. C. , Carlson D. E. , Yee A. , Buchanan B. B. , Leighton T. , Yang W.-S. , Bryan J. C. 
Published: April 2011

AbstractXANES (X-ray Absorption Near Edge Spectroscopy) has been employed to evaluate the efficacy of a process designed to encapsulate and reduce TcO4-in cement matrices, thereby immobilizing Tc. The oxidation state of Se following bioremediation of Se by bacteria has also been determined by XANES. The XANES measurements were performed at the Stanford Synchrotron Radiation Laboratory (SSRL) and the National Synchrotron Light Source (NSLS) at the respective K edges of Tc (21.0 keV) and Se (12.7 keV). Comparison of the XANES spectra of Tc in untreated cement to Tc in slag treated cement and to the chemical shifts of reference materials, shows that the oxidation state of Tc is the same in both cements. Thus, the addition of a reducing agent to the cement formulation does not significantly reduce the TcO4-. The common soil bacterium,Bacillus subtilis, is known to incorporate Se on or within the cell wall when exposed to a Se(IV) solution. The Se XANES spectra ofB. subtilis, as well as bacillus isolated from selenium rich soil, show that the organisms reduce selenite to the red allotrope of elemental Se.
Routes to Deagglomerated Nanopowder by Chemical
Synthesis
Authors: Burgard Detlef , Kropf Christian , Nass Rüdiger , Schmidt Helmut 
Published: April 2011

ABSTRACTThe concept of tailored interfaces has been applied to the synthesis of
nano-scaled Y2O3/ZrO2 powders. The
microemulsion technique as well as the thermodynamically controlled growth
reaction have been utilized for this purpose. Both methods yielded
agglomerate free amorphous powders with particles sizes of 8 nm and 15 nm,
respectively. Cubic zirconia was obtained by calcination between 300 and 400
°C and crystallite coarsening was not observed. The calcined powders could
be redispersed by treating them with tertiary amines in aqueous
solutions.