bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interfacial Structure of Lattice Mismatched bcc(110)/bcc(110) Transition Metal Superlattices
Authors: Fullerton Eric E. , Mini S. M. , Bommannavar A. S. , Sowers C. H. , Ehrlich S. N. , Bader S. D. 
Published: March 2011

ABSTRACTWe present structural characterizations of a series of sputtered Fe/Nb and V/Nb superlattices by high-angle x-ray diffraction. Diffraction scans were performed with the scattering vector at various angles (χ) with respect to the layers. χ=0° diffraction spectra (normal to the layers) were fitted to a general structural model to determine the (110) lattice strains, interfacial disorder and interdiffusion. χ>0° spectra probe the lattice strain of the individual layers and the in-plane interfacial coherence. Both systems form incoherent interfaces above a critical modulation wavelength (ΛC). At ΛC, the Fe/Nb system undergoes a crystalline-to-amorphous transition while the V/Nb forms in-plane coherent interfaces.
Synchrotron Radiation Induced Surface Reactions: A New Method for Metal Film Deposition on Semiconductors
Authors: Zanoni Roberto , Piancastelli Maria Novella 
Published: March 2011

ABSTRACTA systematic investigation of the adsorption properties of several organometallic compounds on silicon surfaces is reported. In this framework, a new method to deposit thin metal films on silicon surfaces is described, which is based on a synchrotron radiation induced photodecomposition reaction. The precursors are metal carbonyls adsorbed on single-crystal Si surfaces in ultrahigh vacuum conditions. Irradiation of these adsorbatesubstrate systems with unmonochromatized synchrotron radiation (“white light”) induces a chemical reaction leading to a thin metal film on the surface. This process has been monitored in situ by photoemission. The fingerprint for the film formation is the appearance of a clear Fermi edge in the valence band. We have been able to deposit thin films of Mo, W and Fe on Si(111) surfaces. This method offers several advantages over traditional techniques, and namely the mild conditions and the limited number of process steps. An intriguing future development under testing is the possibility of creating ordered patterns on the surface.
Diffraction Anomalous Fine Structure: A New Technique for Probing Local Atomic Environment
Authors: Pickering Ingrid J. , Sansone Michael , Marsch James , George Graham N. 
Published: March 2011

ABSTRACTDiffraction anomalous fine structure (DAFS) is the fine structure in the intensity of an X-ray diffraction peak in the vicinity of an absorption edge. DAFS is measured by monitoring the intensity of a diffraction peak as a function of the incident X-ray energy as it is scanned through an absorption edge. It combines the short range structural sensitivity of X-ray absorption spectroscopy with the long range periodicity of X-ray diffraction, and can provide structural information which is not available from these techniques alone, or in combination. We present a methodology which allows extraction of a specific X-ray absorbance spectrum from the DAFS spectrum, and illustrate it for KMnO4. We also demonstrate the ability of DAFS to separate the contributions to the X-ray absorption spectrum of the tetrahedral and octahedral cobalt sites in the spinel Co3O4.
X-Ray Observation of Stress Gradients and Precipitation in Passivated AL-0.5% Cu Films
Authors: Besser Paul R. , Brennan Sean , Bravman John C. 
Published: March 2011

ABSTRACTGrazing incidence x-ray scattering has been used with a synchrotron source to characterize the stress gradients during thermal cycling in 1.0 μm thick Al-0.5%Cu films passivated with silicon nitride. The films were cycled between room temperature and 400°C. The stress-temperature behavior is quantitatively similar to that measured for unpassivated films. The presence of an inhomogeneous strain is documented at low temperatures. The dissolution and precipitation of Al2Cu is suggested as an explanation for the gradients and asymmetric x-ray peak broadening.
High Resolution Photoelectron Study of the Optimum Oxygen Doping Levels in High TcSuperconductors
Authors: Kelley R. J. , Cai X. C. , Ma Jian , Larbalestier D. C. , Onellion M. 
Published: March 2011

ABSTRACTThe materials and electronic properties of the new cuprate superconductors are critically dependent upon both the oxygen stoichiometry and annealing history of the material. Improving Jc, Tc, and determining the underlying mechanism of superconductivity depend on a better understanding of these effects. In the study of Bi2Sr2CaCu2O8-δwe have combined standard material characterization techniques with high resolution angle resolved photoemission spectroscopy and resonant photoemission spectroscopy to illuminate these issues. Specifically, we make high quality single crystals of BSCCO and then anneal in different atmospheres and pressures. We correlate this withc-axisresistivity, a, b-plane resistivity, and resonant photoemission spectroscopy. In this way we can explain the macroscopic transport properties in terms of the electronic properties of the material determined from photoemission. We find that we can change the c-axis resistivity from non-metallic to metallic by adding oxygen and that this correlates with increased oscillator strength in thec-axisdirection at the Fermi level.
Electronic Structure of Cr2O3 Studied by Photoemission Spectroscopies
Authors: Li Xiaomei , Henrich Victor E. , Saitoh Tomohiko , Fujimori Atsushi 
Published: March 2011

ABSTRACTThe electronic structure of single-crystal Cr2O3 has been studied by Cr 2p core-level XPS and valence-band UPS spectroscopies. A cluster configuration-interaction analysis was applied to investigate the nature of the satellite in the Cr 2p core-level photoemission spectrum. It is argued that the satellite can be understood as a charge-transfer satellite, and Cr2O3 is found to be situated at the boundary between the Mott-Hubbard and the charge-transfer regimes. The values of the charge-transfer energy, Δ, the Coulomb correlation energy, U, and the ligand 2p-cation 3d hybridization energy, T, found from fitting the Cr 2p XPS spectrum were also used to analyze the valence-band UPS spectrum. The comparison between the experimental spectrum and the spectrum from theoretical fitting is fair.
In-Situ Quasi-Real Time Observations of the Deformation of α-Brass Bicrystals via Synchrotron X-Ray Topography
Authors: Zeng Z. , Rek Z. , Bilello J. C. 
Published: March 2011

ABSTRACTReal-time studies of the deformation behavior of a-brass bicrystals were conducted via in-situ synchrotron white beam X-ray topography (SWBXRT). The object of this work was to understand the role of internal interfaces such as grain boundaries, in controlling the mechanical behavior of materials. A brass bicrystal, in which the two grains made 5° of tilt and 11° of twist with respect to each other was grown by the Bridgman method. Observations were performed by straining the bicrystal in a microtensile stage while stop-action X-ray diffraction topographs were taken. Slip initiated in the grain with the most favorable Schmid factor at a stress level of 1.4MPa which was 5% of the macroyield stress. Since the grain boundary acted as a barrier to slip, the next grain did not slip until the dislocation pile-up at the grain boundary reached a critical value.
Anisotropic Phase Separation in Amorphous Fe-Ge Alloys
Authors: Regan Michael J. , Bienenstock Arthur 
Published: March 2011

ABSTRACTMagnetron sputtered amorphous FexGe100-x films have been examined with anomalous small-angle x-ray scattering (ASAXS) in an attempt to characterize composition fluctuations which have been previously reported in this system. Films grown under various deposition conditions have been studied, with the scattering vector both in and oblique to the plane of the films, to search for anisotropy. By manipulating the deposited power flux and rates of growth, films which have the same composition can be grown to different states of phase separation. The total correlation functions have been calculated from the oblique scattering experiments. The anisotropy can be successfully modeled as a close-packing of oriented prolate ellipsoidal particles, with the elongated axis along the direction of film growth. A method for using these measurements to determine the compositions of the phase-separating species has been developed and utilized. The results indicate phase separation into a-Ge and a-FeGe2 for the a-FexGe100-x (x<33) alloy.
X-Ray Absorption Spectroscopic Study of Copper in an Amorphous Copper-Silicate: Chrysocolla
Authors: McKeown David A. 
Published: March 2011

ABSTRACTXANES and EXAFS data indicate that chrysocolla does not contain domains of Cu-metal or Cu-oxides as previously hypothesized, but is most similar to dioptase, a chemically homogeneous crystalline Cu-silicate. The first shell around Cu in chrysocolla is similar to that in dioptase, indicating Cu is coordinated by four oxygens. However, the second shell around Cu in chrysocolla is significantly different than the second shell surrounding Cu in dioptase. The larger amplitude second shell for chrysocolla compared with dioptase is found to be primarily due to differences in the Cu-Cu environments between these two materials.
X-Ray Absorption Spectroscopy of Nitrogenase Mo-Fe Protein
Authors: Chen J. , Christiansen J. , George S. , Tittsworth R. , Hales B. , Campobasso N. , Bolin J. , Cramer S. P. 
Published: March 2011

ABSTRACTWe have studied both the atomic and electronic structures of nitrogenase Mo-Fe proteins using EXAFS and L-edge spectroscopy. The Mo and Fe K-edge EXAFS data show not only 2.37, 2.70, 2.29, and 2.63 Å first shell Mo-S, Mo-Fe, Fe-S, and Fe-Fe distances, but also 3.8, 4.3 and 5.1 Å second shell Fe-Fe, Fe-S, and Mo-Fe interactions. These observed distances are consistent with recent crystallographic models for the M-center. The average Mcenter distances have been defined with unprecedented accuracy. The nitrogenase Fe L-edge spectra have been obtained for the first time, and the result suggests that the Fe exists in both Fe2+and Fe3+states.
Ionic Transport in Silicate Glasses Modelled from the Local Structure
Authors: Greaves G. Neville , Baker G. J. , Dent A. J. , Oversluizen M. , Ngai K. L. 
Published: March 2011

ABSTRACTComprehensive studies using X-ray Absorption Fine Structure (XAFS) spectroscopy of the local environments in oxide glasses of alkalis like Na point to the existence of channels of modifying oxide within the glass forming network - a Modified Random Network or MRN. It has been proposed that these are the primary pathways for ionic conduction. Such microsegregation demands a high alkali coordination for non-bridging oxygens. This has now been confirmed from analysis of the O near edge XAFS of silica and sodium disilicate glass. Dielectric relaxation in oxide glasses provides considerable evidence for the cooperative action of alkali ions. The MRN has been used to develop specific microscopic models for ionic transport based on XAFS and incorporating correlated ionic movement. These quantitatively predict the ionic conductivity of silicate and aluminosilicate glasses and the compositional dependence of the activation energy with alkali concentration.
High Resolution Tem Studies of Defects Near Si-SiO2 Interface
Authors: Mazur J. H. , Washburn J. 
Published: March 2011

ABSTRACTSmall defects with habit parallel to {100} and {311} matrix planes were observed using high resolution transmission electron microscopy (HREM) within 100 nm from the Si-Si02 interfaces after one step oxidation in dry O2 at 900°C, 1000°C and 1150°C of Czochralski (CZ) grown [100] p type boron doped, 1.5 − 20 Ω cm Si wafers with concentrations of oxygen1.4 × 10 18cm−3 and carbon 4. − 10. × 10 16 cm−3.The defects were less than 10 nm wide and I nm thick. The {100} and {311} defect are interpreted tentatively as thin silica plateletes and {311} stacking faults respectively. Distribution of defects near the interface was random although their density appeared to be lower for higher oxidation temperatures. It is not yet clear whether the defects were formed during the oxidation treatments or were present near the surfaces of the asreceived wafers.
Electron Microscopy of Semiconductors Reconstructed Surfaces
Authors: Petroff Pierre M. 
Published: March 2011

ABSTRACTSurface sensitive transmission electron microscopy (SSTEM) and reflection electron microscopy (REM) have been used to analyze the Si (111) 1×1 → 7×7 surface reconstruction. The SSTEM and transmission electron diffraction results for the Si (111) 7×7 surface are interpreted using several possible “surface dislocation” models. The SSTEM and REM techniques have also been applied to the GaAs (100) MBE deposited surfaces. The rough surface topography for the c(4×4) reconstructed surface is attributed to surface steps motions and bunching upon interruption of the MBE deposition.
Tem Observation of defects in InGaAsP and InGaP Crystals on GaAs Substrates Grown by Liquid Phase Epitaxy
Authors: Ueda O. , Isozumi S. , Komiya S. , Kusunoki T. , Umebu I. 
Published: March 2011

ABSTRACTDefects in InGaAsP and InGaP crystals lattice-matched to (001)-oriented GaAs substrate successfully grown by liquid phase epitaxy, have been investigated by TEM and STEM/EDX. Typical defects observed by TEM are composition-modulated structures, dislocation loops, non-structural microdefects, and stacking faults.
Epitaxy of Bcc and Hexagonal Metals on Fcc(001) Substrates
Authors: Grovenor C.R.M. , Smith D.A. 
Published: March 2011

ABSTRACTA variety of bcc and hexagonal metals have been deposited onto fcc(001) surfaces held at between 150 and 350°C. The epitaxial relationships developed between deposit and fcc substrate have been investigated , and the application of current theories of the energy of interphase boundaries to explaining these results is critically discussed.
Microanalysis with high Spatial Resolution
Authors: Batson P. E. , Grovenor C. R. M. , Smith D. A. , Wong C. 
Published: March 2011

ABSTRACTElemental microanalysis, using x-rays and electron energy loss scattering, has been shown to be possible with electron beam probe sizes down to 0.5nm. This paper will discuss some practical problems, such as specimen drift, signal magnitude, and probe-specimen interaction when the probe is made very small. These problems have arisen in two studies: 1) an investigation of as segregation in poly-crystalline Si and 2) imaging of metal spheres with surface and bulk plasmon inelastic scattering.
Reversible Photo-Induced Currents in Epitaxial Pb(Zr0.52Ti0.48)O3 Thin Films
Authors: Lee J. , Esayan S. , Prohaska J. , Safari A. 
Published: March 2011

AbstractThe pyroelectric and photogalvanic effects have been studied extensively in epitaxial Pb(Zr0.52Ti0.48)O3 (PZT) thin films. For the first time, photo-induced currents, which were completely reversible by electrical voltage, were observed in ferroelectric thin films. The photo-induced currents exhibited transient and steady state components. The transient component, in turn, consisted of two components with fast (<1 µs) and slow (∼hours) relaxation times. The mechanisms of the photo-induced currents in PZT films and their possible application in non-destructive readout ferroelectric memory are discussed.
Reactive ion Etching of Pt/PbZrxTi1−xO3/Pt Integrated Ferroelectric Capacitors
Authors: Van Glabbeek J.J. , Spierings G.A.C.M. , Ulenaers M.J.E. , Dormans G.J.M. , Larsen P.K. 
Published: March 2011

AbstractDry etching of a Pt/PbZrxTi1−xO3/Pt (Pt/PZT/Pt) ferroelectric capacitor stack with CF4/Ar plasmas with a reactive ion etching process for the fabrication of micrometer-sized integrated ferroelectric capacitors is described. The etch rate for both Pt and PZT is determined as a function of the process settings: Power, pressure and CF4-Ar gas flow ratio. A chemical enhancement of the etch rate is found for PZT. It is shown that it is possible to etch the Pt/PZT/Pt ferroelectric capacitor stack in a CF4/Ar plasma in a single lithographic process using patterning by photoresist masking. Redeposition processes occurring during etching are described.
Deposition, Structural Characterization, and Broadband (1KHz-40GHz) Dielectric Behavior of BaxTi2-xOy Thin Films
Authors: Liu W.-T. , Cochrane S. , Beckage P. , Knorr D. B. , Lu T.-M. , Borrego J. M. , Rymaszewski E. J. 
Published: March 2011

AbstractAn ion assisted deposition technique, called Reactive Partially Ionized Beam (RPIB) deposition, was used to prepare amorphous BaxTi2-xOy thin films at a low substrate temperature (<60°C). The stoichiometry of the films varied from ×=l.0 for BaTiO3 to ×=0.2 for Ti-rich films. The optical, thermal, and broadband electrical properties of this class of thin film dielectrics were systematically studied. A lμm BaxTi2-xOy film is optically transparent with a band gap of 4.6eV. Both transmittance and bandgap decrease when the films are increasingly enriched with Ti. The Ti rich films remain amorphous at 600°C while the stoichiometric BaTiO3 crystallizes into the perovskite structure. Annealed Ti rich films are thermally stable (>700°C) with low leakage (<0.lμ/cm2 at 0.5MV/cm) and moderately high dielectric constant (εr = 15-35). Polycrystalline BaTiO 3 deposited at 600°C on a Pt/Ta/SiO2/Si substrate has an εr = 400. Capacitor structures with various metallizations were used to evaluate the dielectric properties, such as breakdown strength, leakage, εr and tanδ from DC to 600MHz. A generic test vehicle was designed and fabricated to extend the frequency domain characterization of the dielectrics up to 40GHz. No dispersion of εr was observed in this frequency range for amorphous BaxTi2-xOy.
Correlations Among Degradations in Lead Zirconate Titanate thin Film Capacitors
Authors: Yoo In K. , Desu Seshu B. , Xing Jimmy 
Published: March 2011

AbstractMany attempts have been made to reduce degradation properties of Lead Zirconate Titanate (PZT) thin film capacitors. Although each degradation property has been studied extensively for the sake of material improvement, it is desired that they be understood in a unified manner in order to reduce degradation properties simultaneously. This can be achieved if a common source(s) of degradations is identified and controlled. In the past it was noticed that oxygen vacancies play a key role in fatigue, leakage current, and electrical degradation/breakdown of PZT films. It is now known that space charges (oxygen vacancies, mainly) affect ageing, too. Therefore, a quantitative ageing mechanism is proposed based on oxygen vacancy migration under internal field generated by either remanent polarization or spontaneous polarization. Fatigue, leakage current, electrical degradation, and polarization reversal mechanisms are correlated with the ageing mechanism in order to establish guidelines for simultaneous degradation control of PZT thin film capacitors. In addition, the current pitfalls in the ferroelectric test circuit is discussed, which may cause false retention, imprint, and ageing.
Ferroelectric La-Sr-Co-O / Pb-Zr-TI-O / La-Sr-Co-O Heterostructures on Silicon: Reliability Testing
Authors: Ramesh R. , Sands T. , Keramidas V. G. , Fork D.K. 
Published: March 2011

AbstractWe report results of pulsed electrical testing of ferroelectric Pb0.9La0.1Zr0.2Ti0.8O3 thin film capacitors with symmetrical La-Sr-Co-O top and bottom electrodes at room temperature and at 100°C. They have been grown on [001] Si with a Yttria stabilized zirconia (YSZ) buffer layer. A layered perovskite “template” layer (200-300Å thick), grown between the YSZ buffer layer and the bottom La-Sr-Co-O electrode, is critical for obtaining the required orientation of the subsequent layers. When compared to the capacitors grown with Y-Ba-Cu-O (YBCO) top and bottom electrodes, these structures possess two advantages : (1) the growth temperatures are lower by 60-150°C; (ii) the capacitors show a large remnant polarization, δP, ( δP = switched polarization -non-switched polarization), 25-30 μC/cm2, for an applied voltage of only 2V (applied field of 70kV/cm). The fatigue, retention and aging characteristics of these new structures are excellent at both room temperature and at 100°C.
Plasma Enhanced Metalorganic Chemical Vapor Deposition of Conductive Oxide Electrodes for Ferroelectric BaTiO3 Capacitors
Authors: Zhang Jiming , Cui Guang-Ji , Gordon Douglas , Buskirk Peter Van , Steinbeck John 
Published: March 2011

AbstractThin film heterostructures of BaTiO3/YBa2Cu3O7-x (YBCO) and BaTiO3/LaxSrl-xCoO3 (LSCO) have been prepared by a novel single liquid source plasma-enhanced metalorganic chemical vapor deposition (PE-MOCVD) process. Both YBCO and LSCO are conductive oxides with perovskite structure and lattice parameters closely matched to BaTiO3. YBCO films were found to deteriorate after the deposition of BaTiO3 under the PE-MOCVD conditions as revealed by X-ray diffraction and electrical characterization. LSCO thin films prepared by PE-MOCVD have a mirror-like surface, exhibit low electrical resistivity (p = 200 μΩ-cm at room temperature) and are robust to BaTiO3 deposition. These characteristics make LSCO a promising electrode material for ferroelectric capacitors.
Growth, Microstructures and Optical Properties of KNbO3 Thin Films
Authors: Graettinger Thomas M. , Morris P. A. , Woolcotit R. R. , Zumsteg F. C. , Chow A. F. , Kingon A. I. 
Published: March 2011

AbstractPotassium niobate, KNbO3, possesses high nonlinear optical coefficients making it a promising material for frequency conversion into the visible wavelength range. While epitaxial thin films of KNbO3 have been reported [1,2], only limited data exists concerning the optical loss mechanisms and nonlinear optical properties of these films. In this study, epitaxial thin films of KNbO3 have been grown using ion beam sputter deposition and evaluated in terms of their microstructures and optical properties. Characterization of the microstructures of these films includes the in-plane epitaxial relationship to the substrate. The relationships between the growth parameters and microstructures developed to the indices of refraction and the optical losses (absorption and scattering) are discussed.
Aerosol Routes to Perovskite Phase Mixed Metal Oxides
Authors: Chandler C.D. , Powell Q. , Hampden-Smith M.J. , Kodas T.T. 
Published: March 2011

AbstractSub-micron sized metal oxide particles were formed via aerosol decomposition using single-source mixed metal-organic precursors specifically designed to decompose at low temperatures. The advantage of these single-source precursors over mixtures of individual precursors is that each particle contains a fixed stoichiometry and molecular level homogeneity. Furthermore, the loss of volatile intermediates (such as PbO) may be avoided. Aerosol processing routes can produce uniform sub-micron sized powder that can be sintered at low temperatures for various thin film and membrane applications. The single-source precursors were prepared in pyridine by reaction of divalent metal α-hydroxycarboxylates of general empirical formula A(O2CCMe2OH)2 (where A = Pb, Ca, Sr, Ba; Me = methyl) with metal alkoxides (for example, Ti(O-i-Pr)4) with the elimination of two equivalents of alcohol. These species were then hydrolyzed in solution and yellow powders were isolated by removal of the pyridine solvent in vacuo. These powders were dissolved in water and used to prepare mixed metal oxide powders via spray pyrolysis. Phase-pure submicron-sized particles of PbTiO3 and BaTiO3 were produced at temperatures of 600-900 °C. The particles were hollow, ranged in size from 0.1 to 1 μm and consisted of 30-50 nm crystallites.