bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrochemical Pitting And Repassivation On Icosahedral AL-CU-FE, And A Comparison With Crystalline Phases
Authors: Spurr Nicholas A. , Pinhero Patrick J. , Sordelet Daniel J. , Hebert Kurt R. , Thiel Patricia A. 
Published: April 2011

AbstractWe report the electrochemical potentials at which localized pitting and repassivation occur on icosahedral Al-Cu-Fe, and on a series of related alloys and elemental metals. The electrochemistry occurs in a buffered NaCI solution, pH 8.4. Under these conditions, pitting and repassivation appear to be controlled mainly by the chemical composition of the alloy, although the quasicrystalline phase displays an anomalous resistance to repassivation. Corrosion of this phase proceeds by dissolution of Al and Fe, leaving behind pits which are Cu-enriched.
Processing Of Al-Cu-Fe Quasicrystalline Single Grains
Authors: Lograsso T. A. , Ross A. R. 
Published: April 2011

AbstractThe phase equilibria of the Al-Cu-Fe quasicrystalline phase (y phase) is complex and conventional crystal growth techniques like the Bridgman and Czochralski methods are not applicable in preparation of large crystals. Large single grains of the y phase been have prepared by either slow cooling or isothermal anneals. In the later technique, arc melted ingots were subjected to either single or multiple heat treatments between 825 and 840°C to encourage grain growth. Following heat treatment, grains of the icosahedral phase are found either as isolated pentagonal-faceted crystals within the ingot or within clusters of intergrown grains. The growth of the large grains is independent of the sample processing history of the sample, is facilitated by the presence of liquid at the growth temperatures and is constrained by the physical dimension of the ingot. The microstructure of both grain types is similar containing a minor quantity (on the order of 5–10 %) of a second phase and a high degree of porosity in the as-grown state. The second phase is usually present as a thin layer between adjacent grains or associated with a pore within a single grain. The grain porosity is distributed throughout the ingot. These defects can be removed through post-growth hot isostatic pressing and anneal treatments.
Hybridization Effect On Electron Transport Properties Of Rhombic Triacontahedral-Type Al60-xMg40Xx. (X = Zn, Cu, Ag, and Pd) 1/1-Cubic Approximants
Authors: Mizuno T. , Takeuchi T. , Mizutani U. 
Published: April 2011

AbstractWe have measured in this experiment the XPS (x-ray photoemission spectroscopy) and SXES (soft x-ray emission spectroscopy) valence spectra, the electrical resistivity, the Hall coefficient and the Rietveld structural analysis for a series of the RT-type (Rhombic Triacontahedron) Al60-xMg40Xx (X = Zn, Cu, Ag and Pd; x = 5 - 40) 1/1-approximants. The electrical resistivity at 300 K is successfully analyzed in terms of the carrier concentration per atom e/a and the ratio of the lattice constant over the “ideal” lattice constant defined as LCR. The latter is chosen as a quantitative measure of the degree of the hybridization between Al and transition metal elements Cu, Ag and Pd. We show that a sharp resistivity increase with increasing the concentration of the transition metal element can be attributed to the deepening of the pseudogap at the Fermi level, which is brought about by the combination of the Fermi surface-Brillouin zone interaction and the growth of the hybridization effect.
Optical Properties Of Icosahedral Al59 B3 Cu25.5Fe12.5 Quasicrystalline Alloy
Authors: Demange V. , Vigneron B. , Maciuzaud F. , Dubois J. M. 
Published: April 2011

AbstractWe report an optical investigation of single phase icosahedral Al59B3Cu25.5Fe12.5. The optical conductivity presents a striking depression at low frequencies and a prominent peak at 3 104 cm−1.A phenomenological analysis of the conductivity allows us to correlate the high energy excitations to a mechanism of electron hopping.
Mechanical Properties Of Quasicrystal Dispersed Al-Li-Cu Alloy
Authors: Okada T. , Nakamura T. , Mitsugi K , Kozawa K , Matumura T , Ishii H , Ozu Y. , Oguri K. , Nishi Y 
Published: April 2011

AbstractTo apply the ductile structural materials, the quasicrystal dispersion in aluminum alloys is one of effective methods. We have investigated mechanical properties of quasicrystal dispersed Al- Li-Cu alloy prepared by the twin-type piston anvil apparatus. The slow cooled samples are hard and ductile. The evaluated values of brittleness are from 6.0 to 14 erg for Ef, from 0.52 to 0.73MNm−3/2 for K1c and from 5.5 to 7.7 Nm−1 for Gic for the fastest and slowest cooled samples, respectively. The hardness of the quasicrystal dispersed Al-Li-Cu alloy is higher than that of the other commercial aluminum alloys. Based on the relationship between Vickers hardness and proof stress of aluminum alloys, we estimate the specific strength of Al-Li-Cu quasicrystal alloy. The maximum value is the higher than that of Ti alloys.
Study Of Al Surface Segregation In Icosahedral A162Cu25.5Fe12.5
Authors: GIL-GAVATZ M. , Rouxel D. , Pigeat P. , Weber B. , Dubois J.-M. 
Published: April 2011

AbstractSurface segregation of aluminium was observed during oxidation experiments of icosahedral A162Cu25.5 Fel12.5, performed in-situ and at different temperatures in the ultra-high vacuum chamber of a scanning Auger electron spectrometer. Two regimes, below and above 770K, were observed in relation with severe segregation of Al atoms at the surface for T > 770K. We postulate that this temperature dependent segregation rate is representative of the aluminium transport towards the surface of the quasicrystal. By analogy with classical diffusion experiments, we can thus determine reasonable estimates of the activation energy for Al self-diffusion in this quasicrystal. The results are consistent with the existence of phason flips below 770K and thermal vacancies above this temperature.
Formation of Polymer Stabilized Ferroelectric Liquid Crystals using a Fluorinated Diacrylate
Authors: Guymon C. Allan , Bowman Christopher N. , Bowman Christopher N. 
Published: April 2011

ABSTRACTFerroelectric liquid crystals (FLCs) have shown great potential for use in electro-optic and display technology due to their inherently fast switching speeds and bistability. Recently, considerable research has been devoted to FLCs mechanically stabilized by a polymer network. The network is formed typically by in situ polymerization of a monomer dissolved in the FLC. Because of the inherent order in the FLC, the polymerization behavior may be significantly different than what might be expected in solution polymerizations. These deviations result largely from the segregation properties of the monomer in the liquid crystal. One class of monomers, namely fluorinated acrylates, is a likely candidate for inducing novel segregation, polymerization and electro-optic behavior in polymer stabilized ferroelectric liquid crystals (PSFLCs). The use of fluorinated moieties has a significant impact on the phase and polymerization behavior of liquid crystal systems. This study focuses on the polymerization of a fluorinated diacrylate, octafluoro 1,6-hexanediol diacrylate (FHDDA), to form PSFLCs and the consequent impact of the polymerization on the ultimate performance. Interestingly, as the temperature is increased and the order of the system decreases, a dramatic increase in the polymerization rate is observed. This increase is especially prominent for polymerizations in the smectic C* phase for which the rate is more than five times that exhibited at much higher temperatures in the isotropic phase. As with other monomer/FLC systems, the segregation of the monomer plays a role in this polymerization behavior as the monomer segregates between the smectic layers of the liquid crystal. The segregation properties also significantly impact the ultimate electro-optic properties. Both ferroelectric polarization and response time of the PSFLC change markedly with different polymerization temperatures, and approach values very close to those of the neat FLC under appropriate polymerization conditions. This behavior not only provides a unique mechanism for rate acceleration in PSFLCs, but also paves the way for new methods to optimize performance in these materials.
Three-Dimensional Photoreorientation of Self-Organized Azobenzene Chromophores in Liquid Crystalline Polymer Films
Authors: Han M. , Morino S. , Ichimura K. 
Published: April 2011

ABSTRACTPhoto-induced reorientational behavior of films of a liquid crystalline polymer with azobenzene side chains was studied by means of UV-Vis absorption spectroscopy and Fourier transform infrared transmission and reflection-absorption spectroscopy. The incident directions of light for photoisomerization played a critical role in the photocontrol of out-of-plane (three-dimensional) orientation of the azobenzenes in films. Tilted directions of the azobenzene residues were evaluated by using polarized UV-Vis absorption spectra. Photoreoriented states of azobenzene chromophores including photodichroism and tilted alignment were enhanced by successive annealing of photoirradiated films at temperatures close to the glass transition temperature of the polymer.
Internal Stress In Sputtered Silver Nickel Thin Films And Multilayers: Sputtering Pressure And Thickness Effects
Authors: Gergaud P. , Yang H. , PéLissonnier-Grosjean C. , Bottger A. J. , Sandström P. , Sundgren J. E. , Thomas O. 
Published: April 2011

ABSTRACTNanometer thick films are often in a state of high residual stress. This may strongly influence physical properties such as magnetic anisotropy. The aim of our study is to investigate whether the overall stress in multilayers may be tailored via the control of the sputtering parameters or of the individual thicknesses. The coatings investigated were deposited at room temperature by magnetron sputtering on oxidised silicon substrates. Ag/Ni multilayers of superperiod between 4 to 20 nm and thin films (Ag or Ni) 200 nm thick have been deposited under a krypton partial pressure varying between 1 and 8 mTorr. Internal stress measurements were performed by curvature method and x-ray diffraction sin2ψ method. The latter one allows the determination of the stress and of the stress-free lattice parameter in the Ag or the Ni layers whereas the first one gives rise to a measure of the average stress in the coating. The main results are the followings: (i) The stress in Ni thin films changes from compressive to tensile at a pressure between 2 and 5 mTorr whereas Ag thin films are sligthly tensile whatever the pressure; (ii) The stress in multilayers is tensile in Ag and Ni and decreases with sublayer thickness; (iii) The stress free lattice parameter of Ag in thin films or multilayers is independent of the Kr pressure and of the layer thickness and is equal to the bulk value; (iv) On the opposite, the stress-free lattice parameter of nickel decreases with the layer thickness in multilayers and is equal to the bulk value in thin films. These results are discussed in terms of the respective influence of interfacial intermixing and atomic peening mechanism.
Temperature Dependence of Ag/Ni Multilayer Microstructure Studied by in Situ X-Ray Diffraction
Authors: Ghetta V. , Senateur J. P. , manna J. La , Delabouglise G. , Matko I. , Chenevier B. , Sandstrom P. , Sundgren J.-E. 
Published: April 2011

ABSTRACTThe temperature evolution of the microstructure in a series of [111] fiber textured Ag/Ni multilayer samples has been studied by in situ X-ray diffraction. From the recorded pattern analysis, two regimes can be distinguished. At low temperature (TGB = 120–130°C) where diffusion is likely insignificant, the observed reduction of the width and the increase of the intensity (sharp and quick in some cases) of 111 line-profiles indicate that microstress and defects densities possibly located in column/grain boundaries are considerably lowered. At higher temperatures, diffusion of Ag leads to a transformation of the multilayer stacking essentially characterized by the formation of long Ag coherent domains with (111) planes parallel to the film surface accompanied with a similar but minor effect on Ni. In Ag, some 002 texture component also appears upon annealing. A simple model is proposed to describe the metal recrystallization competing with areas where the multilayer stacking is kept nearly unchanged.
In-Situ Characterisation of Precipitation in AI-Cu thin films
Authors: Lokker J. P. , Bottger A. J. , Janssen G. C. A. M. , Radelaar S. 
Published: April 2011

ABSTRACTThe precipitate formation occurring in Al-Cu thin foils with copper concentrations of either 1.15 at.% or 0.3 at.%, has been studied. In-situ X-ray diffraction analysis and differential scanning calorimetry are applied to determine the phases formed and the enthalpy changes in the same samples. Both X-ray diffraction and differential scanning calorimetry indicate that the precipitation behaviour of thin films (about 500 nm thickness) differs significantly from that of bulk material. In the films studied the precipitation of Al2Cu occurs at a much lower temperature than expected on the basis of the (bulk) phase diagram. Moreover, no intermediate phases are observed prior to Al2Cu precipitation. Also the amount of Cu in solid solution (0.20 at%Cu) observed by electron-probe micro-analysis after slowly cooling from 500°C to room temperature, exceeds the solubility of bulk Al-Cu.
Process and Manufacturing Challenges for High-K Gate Stack Systems
Authors: Gilmer M.C. , Luo T-Y , Huff H.R. , Jackson M.D. , Kim S. , Bersuker G. , Zeitzoff P. , Vishnubhotla L. , Brown G.A. , Amos R. , Brady D. , Watt V.H.C. , Gale G. , Guan J. , Nguyen B. , Williamson G. , Lysaght P. , Torres K. , Geyling F. , Gondran C.F.H. , Fair J. A. , Schulberg M.T. , Tamagawa T. 
Published: April 2011

ABSTRACTA design-of-experiments methodology was implemented to assess the commercial equipment viability to fabricate the high-K dielectrics Ta2O5, TiO2 and BST (70/30 and 50/50 compositions) for use as gate dielectrics. The high-K dielectrics were annealed in 100% or 10% O2 for different times and temperatures in conjunction with a previously prepared NH3 nitrided or 14N implanted silicon surface. Five metal electrode configurations—Ta, TaN, W, WN and TiN—were concurrently examined. Three additional silicon surface configurations were explored in conjunction with a more in-depth set of time and temperature anneals for Ta2O5. Electrical characterization of capacitors fabricated with the above high-K gate dielectrics, as well as SIMS and TEM analysis, indicate that the post high-K deposition annealing temperature was the most significant variable impacting the leakage current density, although there was minimal influence on the capacitance. Further studies are required, however, to clarify the physical mechanisms underlying the electrical data presented.
Thermal and Chemical Instability Between Iridium Gate Electrode and Ta205 Gate Dielectrics
Authors: Mao A. Y. , Sun Y. M. , White J. M. , Kwong D. L. 
Published: April 2011

ABSTRACTThe thermal and chemical stability of thin CVD iridium films deposited on thin CVD tantalum pentoxide (Ta2O5) films on Si(100) have been investigated by means of in-situ X-ray Photoelectron Spectroscopy (XPS) and ex-situ Angle Resolved XPS (ARXPS). It was found that upon annealing in vacuum at 800 °C for more than 1 min, tantalum oxide at the Ir-Ta2O5 interface was decomposed and formed metallic tantalum which diffused through Ir, while changes in iridium film itself were negligible. When annealed at 750 °C within 15 minutes, intermediate partially oxidized Ta was formed and coexisted with metallic and oxidized Ta. A portion of metallic Ta near Ir-vacuum interface was subsequently oxidized when the films were exposed in air.
Two Step O2/N2O Plasma Annealing for the Reduction of Leakage Current in Amorphous Ta2O5 Films
Authors: Lau W.S. , Perera M.T. Chandima , Han T. , Sandler N. P. , Tung C.H. , Sheng T.T. , Chu P.K. , Chong T.C. 
Published: April 2011

ABSTRACTAs deposited tantalum pentoxide (Ta2O5) films are amorphous. The films will remain amorphous after O2 or N2O plasma annealing at low temperature. High temperature annealing will produce polycrystalline films where grain boundaries can generate leakage current. Previously, we have shown that N2O plasma annealing is superior to O2 plasma annealing in terms of leakage current reduction for AI/Ta2O5/Si capacitors. However, for TiN/Ta2O5/Si capacitors, the leakage current tends to be higher at low bias voltage for N2O plasma annealing compared to O2 plasma annealing. By adding an 02 plasma annealing step and then comparing TiN/Ta2O5/Si capacitors with two step O2/N2O plasma annealing with respect to similar structures with two step O2/O2 plasma annealing, it can be easily seen that TiN/Ta2O5/Si capacitors with two step O2/N2O plasma annealing have lower leakage current compared to similar structures with two step O2/O2 plasma annealing throughtout the voltage range tested.
The Influence of Damage and Dopant on the Blister Formation in Hydrogen Implanted Silicon
Authors: Hochbauer T. , Nastasi M. , Lau S.S. , Zheng Y. , Mayer J. W. 
Published: April 2011

ABSTRACTWe have studied the formation of surface blisters in <100> n-type silicon following coimplantation with boron and hydrogen. In this work we study the effect of having the boron depth larger than the hydrogen depth. The silicon substrates had four different dopant levels, ranging from 1014 cm−3 to 1019 cm−3. The Si substrates were first implanted with B ions at 240 keV (Rp = 705nm) to a dose of 1015cm−2. Some of the B implanted samples were left in their as-implanted state, others were given a rapid thermal anneal (RTA) at 900°C. Boron implanted and virgin n-type Si samples were then implanted at cryogenic temperatures with 40 keV H+ (Rp= 475nm) to a dose of 5 x 1016 cm−2. Following H+ implantation, all the samples were vacuum annealed at 390°C for 10 minutes and examined for hydrogen blister formation. No blistering was observed in samples implanted with H only. In all cases, the blister depth was consistently found to be strongly correlated with H damage profile rather than the H or B concentration profiles. These results will be discussed in terms of defect-dopant interactions and the influence of doping on H kinetics and H-bubble nucleation.
Transient Enhanced Diffusion of Phosphorus and Defect Evolution in P+ Implanted Si
Authors: Li J. , Keys P. , Chen J. , Law M. E. , Jones K. S. , Jasper Craig 
Published: April 2011

ABSTRACTContinuous scaling of device dimensions requires better understanding of non-equilibrium diffusion phenomena such as transient enhanced diffusion (TED). To this end, it is important to understand the relationship of the defect evolution with TED. Defect evolution in P+ implanted Si has been investigated by transmission electron microscopy (TEM). Secondary ion mass spectroscopy (SIMS) has been used to study phosphorus TED. These studies show that another type of defect, i.e. dot defects are present in P+implanted Si (100 keV, 1.OX104/cm2). The evolution of defects in P+ implants is compared with that in Si+ implants. P+ implants give rise to small dot defects mixed with {311} defects while Si+ implants give rise to only {311} defects. The dot defects and {311} defects in P+ implants dissolve faster than the {311} defects from Si+ implants. The interstitial concentration trapped in the dot defects and the {311} defects from P+ implants is slight lower than that from Si+ implants. Dot defects seem to have only a small role in phosphorus TED. Interaction of silicon interstitials emitted from the dissolution of {311} defects with phosphorus dopant atoms is believed to be the dominant driving force for the TED. There may also be a contribution from dissolution of non-visible phosphorus interstitial clusters (PIC's). Correlation of defect evolution and TED has been addressed.
Modeling and Validation of Sensor and Actuator Dynamics for, And Real-Time Feedback Control of Thermal Chlorine Etching of Gallium Arsenide
Authors: Rosen I. G. , Parent T. , Mancera R. , Chen P. , Madhukar A. 
Published: April 2011

ABSTRACTA dynamic model for the simulation of thermal chlorine etching of gallium arsenide is developed. The primary motivation for the development of the model is the design and testing of real time feedback controllers which rely upon in-situ optical measurements of etch depth obtained via spectroscopic ellipsometry. Unmeasurable parameters which appear in the model are identified, and the model is validated using experimental data. A linear-quadratic controller based on our model is designed and tested.
In-Situ Spectroscopy of Ion-Induced Photon Emission During Metal Nanoparticle Formation in Silica Glass with High-Flux Cu Implantation
Authors: Lay Thi Thi , Amekura H. , Takeda Y. , Kishimoto N. 
Published: April 2011

ABSTRACTIon-induced photon emission from a silica glass irradiated with high-flux Cu ions was measured in a wavelength range from 450 nm to 800 nm, while nanoyarticles spontaneously formed in the silica glass. Current density was varied up to 100 µA/cm2 at a constant total dose of 3×106ions/cm2. The photon emission primarily arose from the vicinity of the substrate surface and consisted of sharp peaks due to neutral and singly-ionized species, Cu(I), Cu(II) and Si(II) ions, as well as a broad-band background. Intensity of Si(II) and Cu(I) increased with increasing current density. On the other hand, Cu(II) did not show a monotonic increase, decreasing around 100 µA/cm2. Measurements of in-situ EDX and ex-situ RBS were also conducted to study the relevant mechanisms. The ion-induced photon emission was attributed to recombination processes of sputtered ions and electrons in the plasma, induced by the high-flux Cu beam.
Modeling and Real-Time Process Monitoring of Organometallic Chemical Vapor Deposition of III-V Phosphides and Nitrides at Low and High Pressures
Authors: Bachmann K.J. , Cardelino B.H. , Moore C.E. , Cardelino C.A. , Sukidi N. , Mccall S. 
Published: April 2011

ABSTRACTThe purpose of this paper is to review modeling and real-time monitoring by robust methods of reflectance spectroscopy of organometallic chemical vapor deposition processes in extreme regimes of pressure. The merits of p-polarized reflectance spectroscopy under the conditions of chemical beam epitaxy (CBE) and of internal transmission spectroscopy and principal angle spectroscopy at high pressure are assessed. In order to extend OMCVD to materials that exhibit large thermal decomposition pressure at their optimum growth temperature we have designed and built a differentially-pressure-controlled (DCP) OMCVD reactor for use at pressures ≤ 6 atm. We also describe a compact hard-shell (CHS) reactor for extending the pressure range to 100 atm. At such very high pressure the decomposition of source vapors occurs in the vapor phase, and is coupled to flow dynamics and transport. Rate constants for homogeneous gas phase reactions can be predicted based on a combination of first principles and semi-empirical calculations. The pressure dependence of unimolecular rate constants is described by RRKM theory, but requires variational and anharmonicity corrections not included in presently available calculations with the exception of ammonia decomposition. Commercial codes that include chemical reactions and transport exist, but do not adequately cover at present the kinetics of heteroepitaxial crystal growth.