bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrical and Optical Properties of Defects in N-Type 4h-Sic
Authors: Evwaraye A. O. , Smith S. R. , Mitchel W. C. 
Published: April 2011

ABSTRACTSeveral n-type 4H-SiC samples grown by the physical vapor transport technique were studied using both thermal and optical admittance spectroscopy. The ionization energy ED for nitrogen donors in 4H-SiC was determined to be 0.053 eV and 0.10 eV below the conduction band. This agrees reasonably well with the values of 0.052 eV and 0.092 eV determined by IR absorption measurements. It is believed that EC-0.053 eV is the ionization energy of the nitrogen atom occupying the hexagonal site (h). The 0.10 eV activation energy has been attributed to the nitrogen atoms occupying the cubic sites(k).The optical admittance studies reveal five conductance peaks. One of these corresponds to the band-to-band transitions from which the bandgap of 3.41 eV was determined at 40K. The other four conductance peaks correspond to transitions from defect levels to the conduction band. These defects are located at EC-1.73 eV, EC-1.18 eV, EC-0.87 eV, and EC-0.72 eV.
Characterization of Mineral Deposits on Plasma-Sprayed HA-Coated Ti-6Al-4V
Authors: Benezra V. , Spector M. , Hobbs L. W. 
Published: April 2011

AbstractPlasma-sprayed hydroxyapatite (PSHA) coatings are often used as the attachment vehicle for the femoral component of a total hip prosthesis. The key to successful hip replacement is the attachment of the femoral stem to the surrounding bone.Within hours of implantation of PSHA-coated Ti-6AI-4V rods in canine bone, bone mineral deposits on the HA coating. These deposits take the form of globular networks of fibrous crystallites. The crystallinity of these deposits was confirmed via high-resolution transmission electron microscopy (TEM) and electron diffraction. We have also characterized the composition of these deposits using x-ray energy-dispersive spectroscopy (XEDS) in the scanning TEM. Finally, we have studied the morphology of the fiber-like crystallites by stereography in the TEM.
Engineering Biomaterials that Exhibit Recognition and Specificity
Authors: Ratner B. D. , Boland T. , Johnston E. E. , Tidwell C. D. 
Published: April 2011

AbstractA set of methods that can be used to create surfaces to accurately control biological reactions is described. These include strategies for inhibiting non-specific reactions, making highly organized surfaces, spatially arraying recognition moieties and characterizing complex surfaces.
Pulsed Laser Deposition of Collagen Thin Films
Authors: Conklin J. A. , Cotell C. M. , Barnett T. W. , Hansen D. C. 
Published: April 2011

AbstractThin films of collagen were prepared by pulsed laser deposition (PLD) at room temperature on Si substrates using a KrF laser (248 nm) over a fluence range from 0.2–1.5 Jcm-2. The effects on film composition and morphology of ambient gas (Ar, Ar/H2O vapor), quenching atmosphere (Ar, Ar/H2O vapor), and fluence were examined. Fourier transform infrared spectroscopy (FT- IR) demonstrated that, independent of deposition parameter, the PLD films contained the characteristic Amide I and II functionalities of the collagen target and indicated that the secondary structure was altered by the PLD process. The surface morphology of the films was a function of the laser fluence and the gas environment during either film deposition or quenching at the end of deposition. Preliminary gel electrophoresis examination of deposited films suggested the collagen had not maintained the triple helical structure of the native collagen. X-Ray diffraction (XRD) indicated that all of the films, deposited under any conditions, were predominantly amorphous.
Aerotaxy: A New Route to Formation of GaAs Nanocrystals from Ga Droplets
Authors: Samuelson Lars , Deppert Knut , Malm Jan-Olle 
Published: April 2011

AbstractA new process, named Aerotaxy, has been developed for growth of quantum dots (QDs) with identical sizes and properties. Self-assembly and intrinsic control of the nanocrystal properties is obtained by (i) an initial selection of spherical droplets of gallium (Ga), all having identical sizes within a few %, employing standard aerosol technology. In a second processing stage (ii) these droplets of gallium are allowed to react with arsine (AsH3), by which the metallic Ga droplets are completely converted into a monodisperse ensemble of galliumarsenide (GaAs) nanocrystals at temperatures as low as 260°C. GaAs nanocrystals, of approximate diameter 10 nm, have been produced and deposited on various substrates. The good crystallinity and stoichiometry of the formed particles are confirmed by transmission electron microscopy studies of individual nanocrystals.
Effect of Interdiffusion on the Subbands in an In0.65Gs0.35As/GaAs Multiple-quantum well Structure on GaAs Substrate at 1.55μm Operation Wavelength
Authors: Chan M. C. Y. , Li E. Herbert , Chan K. S. 
Published: April 2011

AbstractAnalysis of high indium concentration in interdiffused In0.65Gs0.35As/GaAs multiple quantum well (MQW) structure on GaAs Substrate is being studied. This material can achieve operating wavelengths around 1.5gtm Ifor applications in fiber optics communications. The large lattice mismatch problem (over 4.5% in this study) can be solved by using a linearly-graded InGaAs buffer layer for reducing any dislocation between the adjacent layers. Interdiffusion in the MQW structure can modify the composition profile in order to tailor the optical absorption and refraction properties. Results show that this system can have promising device performance operates at around 1.55μm and which base on the more matured and reliable GaAs technology.
Optimal Growth of InGaAs/InAlAs Distributed Bragg Reflectors Lattice-matched on InP Substrates
Authors: Choi S. W. , Lee J. H. , Baek J. H. , Lee E. H. , Lee B. 
Published: April 2011

AbstractDistributed Bragg reflectors composed of InGaAs/InAlAs alternating layers have been grown on InP substrates by MOCVD. To obtain high performance, the growth condition has been traded off between surface roughness and crystal quality. Using in-situ laser reflectometry, the precise control of layer thickness and composition has been achieved for reproducible DBR growth. The optimal mirror performance and sharp interfaces have been observed in the DBR grown at 650'C. In order to avoid band-edge absorption 6% of Al has been added to In 0.53Ga0.47As to produce quarternary In0.53Ga 0.41Al 0.06As/InAlAs Bragg reflector exhibiting high reflectivity at 1.55 μm.
Luminescence Properties of Ytterbium and Oxygen Coimplanted InP
Authors: Lozykowski H. J. , Alshawa A. K. 
Published: April 2011

AbstractIn this work we report a systematic study of the effect of oxygen on ytterbium 4f- 4f emission by coimplanting Yb and O into InP. The PL spectra of InP: Yb and InP: (Yb+O) as a function of annealing temperature and duration were studied. In addition the photoluminescence and kinetic processes were investigated as a function of temperature and excitation intensity.The investigation shows that the codoped oxygen reduces drastically the Yb3+emissioon from SI and n-type InP:Yb under intrinsic excitation. The codoping of Yb and 0 may create a complex involving a YbInand Op. This structured isoelectronic (YbIn- Op) complex, may behave as a deep trap (or a deep donor) located approximately at the middle of bandgap. Exciton bound to such centers will not have sufficient energy to excite the core Yb 4f electrons by Auger direct energy transfer process.
Studies on Domain Inversion in LiNbO3and LiTaO3
Authors: Zhu Y. Y. , Zhu S. N. , Zhang Z. Y. , Ming N. B. 
Published: April 2011

AbstractDomain inverted structures in LiNbO3 (LN) and LiTaO3 (LT) are fabricated by proton exchange followed by rapid heat treatment. The formation and development of the effects of pyroelectric field on domain inversion are investigated. The proton and lithium profiles are measured by SIMS. The Curie temperature of the proton exchanged LT is evaluated by DSC. An internal electric field model is proposed to explain the domain inversion mechanism.
Magnetoluminescence Studies in Ordered InGap2
Authors: Jones E. D. , Schneider R. P. , Mascarenhas A. 
Published: April 2011

AbstractPhotoluminescence measurements on ordered InGaP2 were studied as a function of temperature, laser power density, and magnetic field. The temperature varied between 1.4 and 300 K, the laser power densities ranged from 10 nW/cm2 to 20 W/cm2, and the maximum magnetic field was 13.6 T. The data show two spectra, excitonic and band-to-band transitions, depending upon the incident laser power density. A consistent interpretation of the band-to-band spectrum leads to a spatially separated electron-hole transitions between the ordered domains. Three different mechanisms for spatially indirect transitions are presented. An analysis of the linear data also allows a determination of the valence-band mass in the 100 direction of mv ∼0.25 m0.
Ballistic-Electron-Emission Microscopy (BEEM) Studies of Gainp/GaAs Heterostructures
Authors: O'Shea J. J. , Reaves C. M. , Chin M. A. , Denbaars S. P. , Gossard A. C. , Narayanamurti V. , Jones E. D. 
Published: April 2011

AbstractBallistic-electron-emission microscopy (BEEM) has been used to study band-offsets in n-and p-type GaInP/GaAs heterostructures. We determine room temperature offsets of 30 meV and 350 meV in the conduction and valence bands, respectively, for thin GaInP layers grown by metal-organic chemical vapor deposition (MOCVD) at 610°C. Low temperature (77 K) measurements also indicate at least 90% of the band discontinuity lies in the valence band for these ordered GaInP samples.
Electromigration Failure Distributions for Multi-Layer Interconnects as a Function of Line Width: Experiments and Simulation
Authors: Brown D. D. , Sanchez J. E. , Pham V. , Besser P. R. , Korhonen M. A. , Li C.-Y. 
Published: April 2011

AbstractIn narrow metal lines used for chip level interconnects, the line width can strongly affect the electromigration reliability, typically due to variations in the microstructure and in the mechanical stress state. These variations have a stronger effect as the line width decreases to the order of the metal grain size or less. Electromigration failure distributions were obtained both experimentally and by simulation for realistic interconnect structures with six different line widths, ranging from lμm to 8μm. In order to simulate the electromigration failure distributions, microstructure statistics were obtained (using TEM) and the critical void volume for failure was measured (using SEM) for each line width. The simulated failure times match the experimental failure times for narrow line widths (1-4μm).
Modelling Geometrical Effects of Parasitic and Contact Resistance of FET Devices
Authors: Reeves Geoffrey K. , Harrison H. Barry , Leech Patrick W. 
Published: April 2011

AbstractThe continual trend in decreasing the dimensions of semiconductor devices results in a number of technological problems. One of the more significant of these is the increase in contact resistance, Rc. In order to understand and counteract this increase, Rc needs to be quantitatively modelled as a function of the geometrical and material properties of the contact. However the use of multiple semiconductor layers for ohmic contacts makes the modelling and calculation of Rc a more difficult problem. In this paper, a Tri-Layer Transmission Line Model (TLTLM) is used to analyse a MOSFET ohmic contact and gatedrain region. A quantitative assessment of the influence on Rc of important contact parameters such as the metal-silicide specific contact resistance, the silicide-silicon specific contact resistance and the gate-drain length can thus be made. The paper further describes some of the problems that may be encountered in defining Rc when the dimensions of certain types of contact found in planar devices decrease.
High quality GdSil.7 layers formed by high dose channeled implantation
Authors: Wu M. F. , Vantomme A. , Pattyn H. , Langouche G. , Bender H. 
Published: April 2011

AbstractThin gadolinium silicide layers have been formed by channeled ion beam synthesis. Continuous and heteroepitaxial GdSil.7 layers with a hexagonal structure and a χmin value of 10% are prepared by Gd ion implantation at 90 keV to a dose of 1.3x1017/cm2 at 450°C in Si(111) using channeled implantation. The hexagonal phase of GdSi1.7 is stable up to a temperature of 850°C. Both the crystalline quality and the phase stability are much better than the results obtained by conventional techniques. Annealing at > 900°C suddenly changes the χmin value of the silicide layer from 10% to 100%. X-ray diffraction shows that the phase has changed to orthorhombic. RBS/channeling, x-ray diffraction and transmission electron microscopy are used in this study.
NMR Studies of Hydrofluorocarbon-Cation Interactions and Cation Migrations on Adsorption of Hydrofluorocarbon-134 on Zeolites NaY and CsY
Authors: Grey Clare P. , Poshni Faiza I. , Ba Yong , Corbin David R. 
Published: April 2011

Abstract23Na and 23Na/19F double resonance MAS NMR methods have been used to study the binding of hydrofluorocarbon-134 (CF2HCF2H) in zeolites NaY and CsY. The interaction of HFC- 134 with the sodium cations is so strong that the sodium cations in the sodalite cages (site I') migrate into the supercages to bind to the hydrofluorocarbon molecules.
Effect of Processing Variables on the Microstructure and Mechanical Properties of Microporous Carbon Materials
Authors: Singh M. , Dacek R. F. 
Published: April 2011

AbstractMicroporous carbon materials with different pore and strut sizes have been fabricated by the pyrolysis of furfuryl alcohol resin, triethylene glycol, and p-toluene sulfonic acid mixtures. The resulting materials were characterized by scanning electron microscopy and density measurements. The room temperature flexural strength and modulus of these materials decreases with increasing amount of acid curing agent.
From Graphite to Porous Carbon Containing Nanoparticles through Chemical Reactions
Authors: Hung C. C. , Corbin J. 
Published: April 2011

AbstractPorous carbon containing large quantities of separated individual nanoparticles (2–100 nm) was produced. The chemical process includes fluorination or oxygenation of graphite, and then exposing the product (graphite fluoride or graphite oxide) to metal chlorides. The nanoparticles were metal halides or metal oxides, which could contain dopants if they were added during the synthesis process. The metal to carbon atomic ratio was in the range of 1 (3–6). The chlorides used in this research include those of Pd, Zn, Al and Li. Depending on the synthesis process, the carbon pores could be either filled with the nanoparticles, resulting in near-zero surface area and high metal concentration, or partially filled with nanoparticles, resulting in large surface areas. In this report, near zero surface areas were observed for a product of LiCl in carbon, and a surface area of 75 m2/g was observed for the product of γ- Al2O3 in carbon. Heating these products in 1 atm air allowed the nanoparticles to become fuse together in the form of metal oxide while the carbon was oxidized, producing metal oxides which have the same shape as the carbon precursors (fibers, fabrics, or powder) and large surface areas. These products are potentially useful in the area of batteries, high temperature gas sensors, and catalysts. Also, these products could be used to examine individual nanopartidles, whose electrical, optical, and chemical properties differ from those of their single crystal or amorphous counterparts
Improving Thermal Performance of High Internal Phase Emulsion Polymerized Foams with Maleimide Based Monomers
Authors: Hoisington Mark A. , Duke Joseph R. , Langlois David A. 
Published: April 2011

AbstractThe influence of three N-substituted maleimides on the thermal performance of high internal phase emulsion (HIPE) polymerized foams were investigated. N-propylmaleimide, Nbutylmaleimide, and N-cyclohexylmaleimide were copolymerized with styrene and crosslinked with either divinylbenzene or Bis(3-ethyl-5-methyl-4-maleimide-phenyl)methane in a HIPE polymerization process. All maleimide modifiers produced increases in the foam glass transition temperature (Tg) as a function of the maleimide concentration. The degree of Tg improvement was strongly dependent on the N-substituted maleimide used during processing.
Precipitation of Iron(III) Hydroxides from Homogeneous Solutions
Authors: Deng Yiwei 
Published: April 2011

AbstractThe technique of precipitation from homogeneous solutions was used in this study to simulate the formation of iron(III) hydroxides under conditions similar to those at the redox boundary in natural waters. The technique allowed the precipitation of iron(III) hydroxides to occur when the precipitant iron(III) was slowly generated by the oxygenation of iron(II) and subsequently hydrolyzed. During the precipitation, no pH heterogeneity occurred locally as it was usually observed in the conventional preparation of iron(III) hydroxides in the laboratory. Thus, the rapid hydrolysis of ferric ions and the subsequent polymerization of iron(III) hydroxides were effectively prevented. The iron(III) precipitates formed in this way are more representative of the iron(III) particles occurring at the redox boundary in natural waters than those formed by the conventional procedure in the laboratory. The effect of solutes (e.g., H4SiO4) on the structure, size and shape of the iron(llI) hydroxides formed has also be studied.
The Effect of Hydrophobicity of Silicate Minerals on the Adsorption of Dodecylammonium Acetate
Authors: Huang Picheng , Fuerstenau Douglas W. 
Published: April 2011

AbstractThe interaction between hydrophobic species plays an important role in the adsorption of surfactants. In this paper, naturally hydrophilic quartz and naturally hydrophobic talc were selected as model minerals for studying the adsorption of the cationic surfactant, dodecylammonium acetate (DAA). The effect of the hydrophobicity of minerals on the adsorption of DAA was investigated by measuring zeta potentials, adsorption densities and suspension stabilities as a function of pH in the presence of DAA.
The Solubility of Some Alkali-Bearing Zr Minerals in Hydrothermal Solutions
Authors: Aja S. U. , Wood S. A. , Williams-Jones A. E. 
Published: April 2011

AbstractThe hydrolytic dissolution of some Zr-bearing minerals has been measured in aqueous KCl and KF solutions. Depending on the mineral being investigated, Zr concentrations varied from about 9 ppb to nearly 40 ppm in equilibrated solutions; this validates the notion of Zr mobility in some crustal fluids. At 50 °C, ΔfG were determined (using the measured solubility products) for Na catapleiite, elpidite, vlasovite and weloganite to be -4654.2±5.6, -7391.0±11.6, -5181.0±7.3 and -7130.5±1.0 kJ/mol, respectively. Calculated phase relationships amongst the zirconosilicates found at the Strange Lake peralkaline complex indicate that elpidite and gittinsite cannot coexist stably implying a two-stage hydrothermal mineralization process.
Leakage Currents in CVD (Ba,Sr)TiO3 Thin Films
Authors: Basceri C. , Streiffer S.K. , Kingon A.I. , Bilodeau S. , Carl R. , Buskirk P.C. Van , Summerfelt S.R. , Mcintyre P. , Waser R. 
Published: April 2011

AbstractWe have analyzed the leakage behavior of polycrystalline MOCVD (Ba,Sr)TiO3 thin films as a function of both temperature and field. Of the possible mechanisms, thermionic (Schottky) emission gives a self-consistent description of the temperature and field dependencies of the true leakage current for fields in the range of 240–970 kV/cm, and yields realistic barrier heights of 1.2 eV for Pt as the cathode material. For film thicknesses of interest for use in DRAMs, the capacitance-voltage characteristics are explained via Landau-Ginzburg-Devonshire theory. Preliminary resistance degradation studies are also discussed.
In Situ Investigation of Crystallization Kinetics in Pzt Films by Light Scattering
Authors: Shur V.YA. , Negashev S.A. , Subbotin A.L. , Borisova E.A. , Trolier-Mckinstry S. 
Published: April 2011

AbstractThis paper presents the in situ investigation of the crystallite evolution/growth during annealing of amorphous sol-gel Pb(Zr,Ti)O3 thin films by elastic light scattering. XRD and SEM measurements of partly crystallized films of crystallite evolution were used for verifying the method.
Growth of Metal Alkoxide Solution Derived Epitaxial LiNbO3 Thin Films for Optical Waveguides
Authors: Nashimoto Keiichi , Nakamura Shigetoshi , Moriyama Hiroaki 
Published: April 2011

AbstractSolid phase epitaxial growth of LiNbO3 thin films, using a methoxyethoxide solution process, has been examined for optical waveguide applications. The growth variables such as crystallization temperature, crystallization time, and film thickness have been found to be critical factors in the quality of LiNbO3 thin films. High quality epitaxial LiNbO3 films were grown on sapphire (001) substrates using optimized buffer layers. The LiNbO3 showed single orientation, rocking curve full width at half maximum less than 0.04°, and rms roughness of 2.3 nm, in addition to refractive index of 2.24 and optical propagation loss of 3.0 dB/cm.
The Investigations of Dielectric Properties of BaTiO3 Thin Films on Polycrystalline Pt Substrates by Rf Magnetron Sputtering
Authors: Jang Jin Wook , Cho Woon Jo , Hahn Taek Sang , Choi Sang Sam , Chung Su Jin 
Published: April 2011

AbstractThickness dependence of ferroelectric and structural properties of BaTiO3 thin films were investigated. Stoichiometric BaTiO3 thin films were prepared by off-axis rf magnetron sputtering on polycrystalline Pt substrates at 700°C. Film thickness range was 2,100–20,000Å. Room temperature permittivity, frequency dependence of permittivity, and D-E hysteresis loops were measured and lattice parameters were determined as a function of the film thickness. It has been found that these properties had the strong dependence on film thickness, which was mainly due to grain sizes of BaTiO3 thin films. The main cause of thickness dependence of dielectric properties was thought to be crystallinity and stresses of thin films which is resulted from changes in grain sizes.
Residual Stress Distribution in an Al2O3-Ni Joint Bonded with a Composite Layer
Authors: Wang X.-L. , Rabin B. H. , Williamson R. L. , Bruck H. A. , Watkins T. R. 
Published: April 2011

AbstractNeutron diffraction was used to investigate the residual stress distribution in an axisymmetric A12O3-Ni joint bonded with a 40 vol%A12O3-60 vol%Ni composite layer. A series of measurements was taken along the axis of symmetry through the A12O3 and composite layers. It is shown that after taking into account the finite neutron diffraction sampling volume, both the trends and peak values of the experimentally determined strain distribution were in excellent agreement with calculations of a simple finite element model, where the rule-of-mixtures approach was used to describe the constitutive behavior of the composite interlayer. In particular, the predicted steep strain gradient near the interface was confirmed by the experimental data.