bluuebunny/crossref_metadata_2025_split huggingface dataset:
Low Temperature Mocvd Growth of V/Vi Materials VIA a Me3SiNMe2 Elimination Reaction
Authors: Groshens T. J. , Gedridge R. W. , Lowe-Ma C. K. , Cole Teresa 
Published: April 2011

ABSTRACTFilms of M2Te3 (M = Sb, Bi) were grown on Si(lll) cut 4° off-axis and GaAs(100) substrates between 25°C and 150°C in a low pressure MOCVD reactor via a novel N, Ndimethylaminotrimethylsilane (Me3SiNMe2) elimination reaction using M(NMe2)3 (M = Sb, Bi) and (Me3Si)2Te. X-ray diffraction data indicated that the crystallinity and crystallite orientation of the resulting films were dependent on the substrate structure and growth temperature. Amorphous films were deposited below 50°C. Films deposited at 75°C for Sb2Te3 and 125°C for Bi2Te3 were highly oriented with the (015) reflection plane parallel to the substrate surface. Films of Sb2Te3 deposited at 150°C were highly oriented with the (00ℓ) reflection planes parallel to the substrate surface. The electrical properties and presumably the composition of Bi2Te3 films deposited on Kapton was independent of the V/VI precursor ratio used. This unique deposition reaction provides an alternative route to prepare group V chalcogenide materials which have potential applications in solar cells, reversible optical storage, and thermoelectrics.
Silicon Carbide: the Premier Paradigm for Structural and Microelectronic Device Applications in Severe Environments
Authors: Davis Robert F. 
Published: April 2011

ABSTRACTThe extreme thermal, mechanical, corrosion resistant and electronic properties of SiC provide multiplicative combinations of attributes which allow a variety of products for very different applications. The emphasis herein will be the consideration of both the constant stress creep properties of several types of polycrystalline SiC materials and the characteristics of different SiC-based devices having high power, high frequency and switching applications and which are operational at ≥573K. The controlling mechanism in reaction-bonded SiC within the ranges of temperature and stress of 1848K-1923K and 110–220 MPa, respectively, is glide/climb controlled by climb. The controlling creep mechanism in CVD material at T<1873K is dislocation glide controlled by the Peierls stress; above this temperature, the evidence suggests that dislocation glide/climb controlled by climb becomes an increasingly important mechanism. For sintered α-SiC within the respective temperature and stress ranges of 1670K-2073K and 138–414 MPa, the controlling creep mechanisms are grain boundary sliding accommodated by grain boundary diffusion at T<1800K and lattice diffusion at T> 1920K. By contrast, the continual development of SiC thin film deposition and the device related technologies of doping, contacts and dry etching have culminated in a host of microelectronic devices operable at high temperatures, namely, MOSFET high power devices, MESFET high frequency devices, and switches including p-n junctions and thyristors. The properties of selected devices and circuits made from them are described with an emphasis on their operation at high temperature.
New Strategies for the Fabrication of Enzyme Electrodes
Authors: Alva K. Shridhara , Samuelsont Lynne A. , Kumar Jayant , Marx Kenneth A. , Kaplan David L. , Tripathy Sukant K. 
Published: April 2011

AbstractThe electrochemical properties of o-dianisidine have been studied in both aqueous and organic solvents. This aryl diamine has been electrochemically polymerized on ITO coated glass electrodes and it was determined that the optical properties of these films are influenced by the polymerization conditions. The use of this polymer film as substrate for chemical coupling of biomaterials has been demonstrated with the light harvesting protein, phycoerythrin. Fabrication and bioanalytical application of enzyme electrodes by electrochemical copolymerization of odianisidine with the enzymes glucose oxidase and horseradish peroxidase, modified with odianisidineis described.
Bioactive Void Metal Composites for Orthopedic Implant Devices
Authors: Campbell Allison A. , Graff Gordon L. , Song Lin , Sump Ken R. 
Published: April 2011

AbstractAlthough significant advances have been made to provide mechanically strong and nontoxic metals and alloys, biological integration of devices into natural tissues remains a problem. The Surface Induced Mineralization (SIM) and Void Metal Composite (VMC) processes produce a bioactive porous metal implant coating/device which may address many of the problems associated with conventional processing methods.The VMC process produces materials which have cylindrical pores of uniform diameter which can completely penetrate the structure of the material. The pore diameter, orientation and interconnectivety are easily controlledThe SIM process uses the idea of nature's template-mediated mineralization by chemically modifying the implant to produce a surface which induces heterogeneous nucleation from aqueous solution. SIM produced bioactive coatings provide 1) control of the thickness and density of the mineral phase, 2) a way to coat porous metals, complex shapes and large objects, 3) the ability to coat a wide variety of materials, 4) potential choice for the phase of the mineral formed.
Thin Film Phosphate Based Bioactive Substrates
Authors: Langstaff S , Sayer M , Weaver L , Pugh S , Smith T 
Published: April 2011

AbstractCalcium phosphate based thin films prepared by colloidal sol-gel slow draw dipping of quartz substrates are bioactive to both osteoclast resorption and osteoblast deposition. The bioactivity is related to the presence of mixed crystalline phases in the films generated under different sintering conditions. As the sintering temperature was increased from 800°C to 1000°C, a transition in film composition from calcium hydroxylapatite to alpha-tricalcium phosphate is achieved.
Cu Deposition Characteristics into Submicron Contact Holes Employing Self-Sputtering With a High Ionization Rate
Authors: Shingubara S. , Sano A. , Sakaue H. , Takahagi T. , Horiike Y. , Radzimski Z. J. , Posadowski W. M. 
Published: April 2011

AbstractCu deposition profiles in submicron contact holes are investigated employing the Cu self-sputtering which do not need any inert gas e.g. Ar during sputtering. Excellent bottom coverage in the high aspect ratio contact holes was obtained at a large target-substrate distance in the selfsputtering due to a long mean free path of Cu ions and atoms, although a coverage is poor in Ar sputtering at 6 mTorr. It is also shown that the self-sputtering has low resputtering effect and high self-diffusivity of Cu, while the resputtering predominates in the case of Ar sputtering when DC bias is applied on the substrate. As a consequence, the bottom coverages of the self-sputtered films are much improved than the Ar sputtered ones. The present work strongly suggests that the self-sputtering is promising to fill Cu in sub micron via and contact holes.
Thermal Stability of Nickel Silicide Films
Authors: Das S. R. , XU D.-X. , Nournia M. , Lebrun L. , Naem A. 
Published: April 2011

AbstractIn view of their potential application in ULSI technology, nickel silicide films were formed on undoped and doped Si(100) substrates. Nickel films of varying thicknesses were sputter-deposited onto the substrates and silicidation was performed ex-situ by rapid thermal annealing in nitrogen ambient. The electrical sheet resistance of the silicides was studied as a function of film thickness and annealing temperature. The process window for forming the NiSi phase and the thermal stability of the NiSi phase were determined as a function of film thickness.
Electromigration and Diffusion in Pure Cu and Cu(Sn) Alloys
Authors: Hu C.-K. , Lee K. L. , Gupta D. , Blauner P. 
Published: April 2011

AbstractAtom movements of Cu in pure Cu and Cu(0.5 to 2 wt.% Sn) alloys have been investigated using drift velocity and radioactive tracer techniques. The void growth rate in pure Cu at the cathode end, as a result of electromigration driving force, linearly increases with the applied current density. A marked decrease in the Cu grain boundary diffusivity and electromigration drift velocity is attributed to Sn trapping of Cu atoms and/or binding defects at grain boundaries. The effect is more pronounced at lower temperatures. The activation energies for electromigration and diffusion of Cu in pure Cu grain boundaries were found to be in the range of 0.7 - 0.9 eV. Addition of about 0.5 to 2 wt.% Sn increased these energies to 1.1 - 1.3 eV, respectively which resulted in enhancement of electromigration resistance by several orders of magnitude over that in pure Cu at the field operation temperature.
New Class of Microporous Materials: Porous Metal Phosphonate Thin Films
Authors: Vermeulen Lori A. , Pattanayak J. , Fisher Travis , Hansford Monica , Burgmeyer Scott J. 
Published: April 2011

AbstractSolid state metal phosphonates (M(O3P-R-PO3) or M(O3P-R)2 (M = metal)) have layered structures where the metal atoms lie in planar sheets and the intervening R groups take up the interlamellar space. Microporous metal phosphonates can be prepared by reaction of the metal with a mixture of large and small phosphonates (M(O3P-LARGE)x(O3P-SMALL)2-x. The larger group acts as a pillar that holds the layers apart. Void spaces result from the presence of the smaller groups. The porous nature of these solids make them potential candidates for applications as sensors, size- and shape- selective catalysts, and chromatographic materials. Metal diphosphonates (M(O3P-R-PO3) can also be prepared one layer at a time on a surface, resulting in the construction of interesting superstructures that are not accessible through the solid state synthesis. For example, these superstructures can contain different components in sequential layers and may have applications in energy conversion, vectorial electron transport, and NLO devices. The preparation of microporous thin films would combine the desirable potential applications of the porous solids with the interesting parallel superstructures that can be prepared from the thin film assemblies. We report our progress toward the construction of microporous metal phosphonate thin films. The two methods that are currently being developed include: 1) phosphonate exchange of pre-assembled films, and 2) co-deposition of different large and small phosphonates during film assembly.
Optical Properties of Si Nanoclusters with Passivated Surfaces
Authors: Dinh L. N. , Chase L. L. , Balooch M. , Siekhaus W. J. , Wooten F. 
Published: April 2011

AbstractSi nanoclusters with average size of a few nanometers have been synthesized by thermal vaporization of Si in an Ar buffer gas, and passivated with oxygen or atomic hydrogen. High resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) revealed that these nanoclusters were crystalline. All samples showed strong infrared and/or visible photoluminescence (PL) with varying decay times from nanoseconds to microseconds depending on synthesis conditions. Absorption mainly in the Si cores was observed by photoluminescence excitation (PLE) spectroscopy. The visible components of PL spectra were noted to blue shift and broaden as the size of the Si nanocrystals (nc-Si) was reduced, and there were differences in PL spectra for hydrogen and oxygen passivated nc-Si. Our data can be explained best by a model involving absorption between quantum confined states in the Si cores and emission by surface/interface states.
Graphitized Needle Cokes and Natural Graphites for Lithium Intercalation
Authors: Tran T. D. , Spellman L. M. , Pekala R. W. , Goldberger W. M. , Kinoshita K. 
Published: April 2011

AbstractThe microstructure of carbonaceous materials strongly affect their ability to electrochemically intercalate lithium [1]. The fractional intercalation capacity (x in LixC6) for various types of amorphous and graphitic carbons can vary over a range between 0 to 1. Capacities exceeding that of graphite (372 mAh/g or LiC6) can be obtained from chemically doped (i.e., with phosphorous [2]) materials or from carbonized organic precursors pyrolyzed at low temperatures (<900°C) [3]. Additional chemical effects apparently influence the carbon electrochemical behavior in these cases.
Photonic Band Structure of Nanochannel Glass Materials
Authors: Rosenberg A. , Tonucci R. J. , Lin H.-B. 
Published: April 2011

AbstractWe demonstrate that nanochannel glass (NCG) materials are ideal for investigating twodimensional (2D) photonic band-structure effects. The NCG materials we have studied consist of triangular arrays of glass cylinders embedded in a glass matrix, having center-tocenter nearest-neighbor separations from 0.54 to 1.08 μm. The indices of refraction of the two glasses differ by less than 0.02 in the relevant spectral region. Narrow attenuation features occur whenever the dispersion relation for light propagating within such a periodic dielectric structure crosses a Brillouin zone boundary. The attenuations corresponding to the first Brillouin zone appear in the near-infrared (IR), at wavelengths between 1 and 3 μm, in good agreement with calculations.
Morphological Characterization of Furfuraldehyde Resins Adsorbents
Authors: Sánchez R. , Monteiro S. N. , D'Almeida J. R. 
Published: April 2011

AbstractThe posibility of employing acid catalyzed fufuraldehyde resins as seletive adsorbents has arisen during a comprehensive study of physical-chemical adsorption properties of these materials. The morphology of these resins depend on the synthesis method. Scanning Electron Microscopic studies of these materials which were synthetized, in bulk (FH-M) and solution (FH-D), showed differences in surface density and particle size. Using mercury porosimeter techniques and BET adsorption methods, it was found different pore size distributions and a decrement in surface area when solvent was employed in the synthesis process. By thermogravimetric analysis it was found similar weight losses (6%) of water adsorption and a small differences in thermal stabilities.
Electrical Behaviour of Natural Manganese Dioxide (NMD)
Authors: Gorgulho H. F. , Fernandes R. Z. D. , Pernaut J. M. 
Published: April 2011

AbstractNMD samples from Brazil have been submitted to magnetic and particle size separations and characterized by X-ray diffraction and fluorescence and thermogravimetric analyses. Results showed that simple physical treatments can lead to more than 60% enriched MnO2 materials which could satistify some electrochemical applications. The electrical properties of the samples conditionated as pressed pellets have been investigated by four-points direct current probe and impedance spectroscopy, varying the conditions of preparation and measurement. It is proposed that the higher frequency impedance is equivalent to the intrinsic electronic resistance of the MnO2 phases while at lower frequencies occurs an interphase charge separation coupled with a possible ionic transport. The corresponding contact resistance depends on the article size distribution of the material, the compactation pressure of pellets and the iron content of the materials. The interphase dielectric relaxation does not behave ideally; the depression of the impedance semicircles as shown in the Nyquist plane is assumed to be related to the roughness of the bulk interfaces.
Porous Materials from Fly Ash
Authors: Möller Jorge G. , Shih Wei-Heng 
Published: April 2011

AbstractLarge quantity of fly ash is generated every year from the electric power plants. Due to the shortage of disposal sites and tighter regulations, new viable ways of utilizing fly ash are needed. The formation of a porous material comprising fly ash was investigated. It was found that a porous material can be made by mixing fly ash with phosphoric acid, followed by heat treatment. The porous material is light-weight (bulk density ˜1 g/cm3), machinable, and with reasonable strength. Due to the high percentage of close porosity, the porous material has a great potential for thermal insulation applications.
Surface Precipitation in the Co(II)/Al2O3 Sorption System
Authors: Towle S. N. , Bargar J. R. , Persson P. , Brown G. E. , Parks G. A. 
Published: April 2011

AbstractSurface precipitation is a critically important process in many systems of scientific and technological importance, such as modeling the segregation of contaminants from aqueous to solid phases in groundwater and the dispersion of active phases on catalyst supports. XAFS and TEM studies of Co(II) sorbed on Al2O3 indicate clearly that surface precipitates have formed from solutions that are undersaturated with respect to any known bulk solid Co-bearing phase. These studies indicate that the structure of the precipitates is similar to that of Co(OH)2(s), but it is disordered and has a high concentration (about 30%) of Co vacancies. Using the FEFF 6.011 multiple-scattering code, we have been able to model the XANES spectrum of the precipitate phase by making small modifications to the structure of Co(OH)2(s). The formation of this precipitate phase is consistent with the coprecipitation of Co(II) with Al(III) derived from dissolution of the substrate, forming a double hydroxide. The existence of a phase that is less soluble than the Al(OH)3 and Co(OH)2 endmembers was proved by forming a colloidal coprecipitate from a mixture of Al(III) and Co(II) aqueous solutions, at the same pH and concentration as in the sorption samples; this material was shown to have Co-XAFS similar to that of the sorption samples. We conclude, therefore, that the surface precipitation observed in the Co(II)/Al2O3 system is due to the the formation of a ternary hydroxide of Al and Co. Successful quantitative models of metal-ion transport in groundwater should include the possibility of forming ternary and higher order precipitates that include ions derived from sparingly soluble solids. For the impregnation of catalysts, the process of surface coprecipitation will make it more difficult to produce a well dispersed precursor material.
Formation and Thermal Properties of Layered Nanocomposites with Layered Double Hydroxides and Polyanions
Authors: Oriakhi C. O. , Farr I. V. , Lerner M. M. 
Published: April 2011

AbstractPoly(acrylic acid), poly(vinylsulfonate), and poly(styrene sulfonate) are incorporated between the positively-charged sheets of double hydroxide layers M1-xAlx(OH)2+ (M = Mg, Ca, Co) and Zn1-xM' x(OH)2+ (M' = Al, Cr) to form layered nanocomposites. The resulting nanocomposites contain the LDH sheet structures separated by 7.6 – 17.0 Å, which is sufficient to accommodate polymer bilayers between the LDH sheets.Phase and morphological changes during thermolysis of the nanocomposites with poly(styrenesulfonate) (PSS) are studied by X-ray powder diffraction, scanning and transmission electron micrography, (SEM and TEM) and thermal analyses. Mg4Al2(OH)12CO3·nH2O and the associated PSS / MgAl-LDH nanocomposites show comparable thermal stabilities: the layered structure is lost above 300 °C with the nucleation of MgO and MgAl2O4 phases at approximately 400 and 800 °C, respectively. The PSS / ZnAl-LDH nanocomposite shows complete oxidative pyrolysis of the polyanion at 500 °C, indicating a catalytic effect of zinc oxide on thermolysis. Crystalline oxide products are obtained at approximately 300 °C lower temperature than from thermolysis of Zn6Al2(OH)16CO3·nH2O. SEM and TEM images show that the thermolysis of LDH carbonates produces dense aggregates containing microcrystalline particles, whereas materials obtained from the PSS / MgAl-LDH nanocomposites exhibit a macroporous framework structure.
Dry Etching Issues in the Integration of Ferroelectric Thin Film Capacitors
Authors: Menk G. E. , Desu S. B. , Pan W. , Vijay D. P. 
Published: April 2011

AbstractDry etching is an area that demands a great deal of attention in the large scale integration of ferroelectric thin film capacitors for nonvolatile random access memory applications. In this review, we discuss some of the issues relating to the etching of the ferroelectric films, patterning of the electrodes, device damage caused by the etch process and post-etch residue problems. An etch process that can provide high etch rates and good etch anisotropy for the current candidate ferroelectrics including Pb(Zr, Ti)O3 and layered structure SrBi2Ta2O9 thin films using environmentally benign gases such as hydrochlorofluorocarbons is presented. The etch mechanism for both of these materials was determined to rely substantially on ion bombardment effects. For example, PZT films were etched anisotropically at rates of up to 60 nm/min using CHCIFCF3 gas under high rf power and low gas pressure conditions. Problems remain with respect to the acrosswafer differential etch rates observed when more than one phase is present in the material (e.g., amorphous/pyrochlore + perovskite phases in PZT). Damage caused by the etch process which can lead to changes in device characteristics, including hysteresis and fatigue properties, and the underlying mechanism that causes the damage are discussed. O2 was found to be a suitable etch gas for etching the conductive oxide electrode material RuO2. However, an anomaly in the etch rate was detected upon introduction of a small amount of fluorine containing gas: addition of 2% of CF3CFH2 gas to the O2 plasma increases the etch rate by a factor of four. This can be taken advantage of in obtaining high etch selectivity between the electrode and ferroelectric layers.
Domain Structure of Tetragonal Plt Epitaxial Thin Films on Mgo (001) Single Crystal Substrates
Authors: Kang Y. M. , Ku J. K. , Baik S. 
Published: April 2011

AbstractFerroelectric Pb1−xLaxTiO3 (PLT, x = 0.00 ˜ 0.28) thin films have been prepared on MgO(001) substrates using pulsed laser deposition. The degree of c-axis orientation in PLT films increased as the La concentration (x) increased with systematic changes in lattice constants and transformation strains. For x ≥ 12, the PLT films showed full c-axis orientation.In order to understand why the domain evolution in PLT films changes with the La concentration, we have conducted high temperature X-ray diffraction to simulate the cooling process during which the domain structure is evolved. Lattice constants, degree of c-axis orientation, crystal quality of PLT films were characterized as a function of temperature. Lattice constants along substrate normal direction showed similar characteristics with those of powder. The degree of c-axis orientation just after the phase transformation at the Curie temperature also increased with La concentration. The crystal quality, which is quantified by the line width of diffraction peak, is insensitive to La concentration in paraelectric phase. However, it shows significant variation after the domain structure is evolved.
Leakage Current Behaviors of Ba0.5Sr0.5TiO3 Thin Films on Pt, RuO2, and Pt/RuO2 Bottom Electrodes
Authors: Jo W. , Kim D. C. , Lee H. M. , Kim K. Y. 
Published: April 2011

AbstractBa0.5Sr0.5TiO3 thin films were grown by rf-magnetron sputtering. Pt and RuO2 films were used as bottom electrodes of the Ba0.5Sr0.5TiO3 thin films. Further, a Pt/RuO2 hybrid electrode was adopted as an electrode for the film. Structural properties of the Ba0.5Sr0.5TiO3 thin films were found to be closely related to the type of the bottom electrodes. Dielectric constants of the films on Pt, RuO2, and Pt/RuO2 were measured as 500, 320, and 450 in the range of 100 Hz ˜ 1 MHz, respectively. Leakage current characteristics of the films were also found to be strongly dependent on the type of the electrodes and their microstructures.