bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Katz-Gratias-De Boissieu-Elser Model Applied To The Surface Of Icosahedral A1pdMn
Authors: Papadopolos Z. , Kramer P. , Kasner G. , Burgler D. E. 
Published: April 2011

AbstractThe Katz-Gratias-de Boissieu-Elser (KGdeBE) model for the icosahedral quasicrystals i-AlFeCu and i-AlPdMn is studied and applied to the surface structure of i-AlPdMn.
Neutron Scattering Study Of Antiferromagnetic Correlations In The Zn-Mg-Ho Icosahedral Quasicrystal
Authors: Sato Taku J. , Takakura Hiroyuki , Tsai An Pang , Shibata Kaoru , Ohoyama Kenji , Andersen Ken H. 
Published: April 2011

AbstractMagnetism in the Zn-Mg-Ho icosahedral quasicrystal has been studied by neutron scattering. Powder samples of the icosahedral and related crystalline phases were reexamined to clarify the origin of the previously-reported long-range magnetic order [Charrier et al., Phys. Rev. Lett. 78 (1997) 4637]. The long range order was found to originate from the related crystalline phase, which is a contaminant in the previously-used samples. Whereas for high-quality icosahedral phase, we could detect only magnetic diffuse scattering. This apparently shows the absence of the long range order in the icosahedral phase. The diffuse scattering was studied in detail by using a single quasicrystalline sample. It was found that the diffuse scattering appears as satellites from intense nuclear Bragg reflections. This indicates that corresponding spin correlations can be regarded as developed between spins on the six-dimensional virtual hypercubic lattice. A magnetic modulation vector for the correlations is proposed.
Ising Model Simulation Of Magnetic Structures IN A Zn-Mg-Ho Structure Model
Authors: Matsuo S. , Ishimasa T. , Nakano H. 
Published: April 2011

AbstractSimulated annealing calculations were performed for Ising spins on Ho sites under Ruderman-Kittel-Kasuya-Yosida-like alternating exchange interactions for an icosahedral Zn-Mg-Ho structure model with intent to investigate the magnetic structures at low temperatures. Magnetic structures were analyzed by means of a Patterson function and diffraction patterns arising from spin-dependent scattering amplitudes. The diffraction patterns from the magnetic structure consist of spots at low temperatures in the case of an antiferromagnetic interaction for the shortest distance (3.37 Å) and a ferromagnetic interaction for the second shortest distance (5.46 Å). The Patterson maps indicate a long-range antiferromagnetic correlation. These facts mean that a long-range ordered magnetic structure is realized at low temperatures. The contrast of the diffraction patterns is different from the patterns arising from the spin-independent scattering amplitudes from the Ho sites. A reversed sign interaction, ferromagnetic for the shortest distance and antiferromagnetic for the second shortest distance, results in broad intensity minima in the magnetic diffraction at the positions of strong spots in the spin-independent diffraction by lattice sites. It corresponds to the degradation of the long-range correlation.
Dry Sliding Of Polygrained Quasicrystalline And Crystalline Al-Cu-Fe Alloys
Authors: Sordelet D. J. , Kim J. S. , Besser M. F. 
Published: April 2011

AbstractDry sliding friction and wear experiments were performed with pin-on-disc techniques using WC and brass pins in contact with quasicrystalline (Al65Cu23Fe12) and crystalline (Al50Cu35Fe15and Al70Cu20Fe10) discs, which were prepared by powder metallurgy routes. The contact loads (1, 5 and 10 N) used in this study produced similar coefficients of friction 0.3-0.4 for the Al65Cu23Fe12and Al50Cu35Fe15phases. These values are higher than previously reported for quasicrystalline and related crystalline phases. Possible reasons for these differences are presented. The contrasting wear behavior between different pins and discs is discussed in terms of contact area, oxidation, material transfer mechanisms and fracture characteristics.
Potential Of Quasicrystals And Quasicrystalline Approximants For Utilization In Small Scale Thermoelectric Refrigeration And Power Generation Applications
Authors: Trrit Terry M. , Pope A. L. , Chernikov M. , Feuerbacher M. , Legault S. , Gagnon R. , Strom-Olsen J. 
Published: April 2011

AbstractWe have identified quasicrystals and quasicrystalline approximants as potential candidates for small scale thermoelectric power generation and refrigeration applications. A number of quasicrystalline systems have been investigated, however, the focus in this paper will be on the ALPdMn (typically Al70Pd20Mn10) system. Currently, we are systematically investigating the electrical and thermal transport properties of the AlPdMn quasicrystalline system in relation to differing sample composition, systematic addition of impurities, and different annealing conditions. Several different preparation techniques have been employed in order to determine optimal techniques for maximizing the thermal and electrical properties of this quasicrystalline system for possible thermoelectric applications. Resistivity and thermopower have been performed over a temperature range between 5K and 320K. Thermal conductivity measurements have been performed over a temperature range between 20K and 300K. In the pure, single phase nominally Al70Pd20Mn10 we have observed thermopower values as high as +85 μV/K around room temperature with resistivity values of 1.5 mΩ-cm. Thermal conductivity measurements yield values less than 3 W/m-K. We will discuss how these properties are affected by the parameters we have varied and the trends we have observed so far. We will discuss the future investigations of the electrical and thermal transport properties of quasicrystals in relation to potential thermoelectric applications.
Diffusion In Icosahedral AI-Pd-Mn Quasicrystals
Authors: Mehrer H. , Galler R. 
Published: April 2011

AbstractIn this paper radiotracer diffusion studies from our laboratory on monocrystals of icosahedral quasicrystalline Al-Pd-Mn (i-AlPdMn) are summarized. Diffusion of 65Zn, 54Mn, and 59Fe has been investigated as function of temperature and in the cases of 5 4Mn and 65Zn also as function of hydrostatic pressure. Diffusion of 65Zn was studied to ‘simulate’ Al diffusion. Over a very wide temperature range no deviation from Arrhenius-behaviour is found. Some preliminary results of 114m In diffusion are also reported. The diffusivities in i-AlPdMn reveal parallels to foreign atom diffusion in Al suggesting a vacancy-type mechanism of diffusion for i-AlPdMn. Signs and magnitudes of the activation volumes of +0.67 Ω (Ω = mean atomic volume) for 54Mn and of +0.74 Ω for 65Zn diffusion in Al-Pd-Mn favour a vacancy mechanism as well.Our results will be discussed together with diffusion studies on i-AlPdMn performed by other groups. The results of Nakajima and coworkers on Mn, Ge, Co and Cr diffusion and the results of Frank and coworkers on Pd and Au diffusion in the high-temperature regime are consistent with the above mentioned conclusion. For the low temperature regime of Pd and Au diffusion the suggested possibility of a phason-related mechanism will be discussed.
Phase Diagrams And Approximants
Authors: Quiquandon M. , Calvayrac Y. , Quivy A. , Faudot F. , Gratias D. 
Published: April 2011

AbstractThe controled growth of large single grain of quasicrystalline phase in metallic alloys is a difficult task that requires a detailled knowledge of the corresponding phase diagram. We discuss the metallurgical specificities of the ternary systems AlCuFe and AlPdMn with respect to single icosahedral grain elaboration. We show that adding a few percents of Silicon in the AlCuFe system leads to stabilize two low order cubic approximants one, α, based on Bergman clusters with a parent F-type icosahedral phase and the other, α', based on Mackay clusters with a parent P-type icosahedral phase. A section of this quaternary phase diagram at constant Si content shows that these cubic phases have no common stability region but are located on opposite sides of an orthorhombic phase that is expected to be a complex synthetic structure mixing both Mackay and Bergman type atomic clusters.
Photoconductivity of Discotic Liquid Crystals Derived from A Long-Chain Tetraphenylporphyrin
Authors: Shimizu Y. , Monobe H. , Mima S. , Higashiyama T. , Fuchita T. , Sugino T. 
Published: April 2011

ABSTRACTPhotoconductivity of a mesogenic tetraphenylporphyrin (TPP) is shown in relation to the mesomorphic phase transition behavior. The TPP mesogen shows two types of mesophases having smectic-like order (lamellar mesophases : DL and DLC phases named in this work) and the photocurrent changes stepwise at the phase transitions with non-Arrhenius dependence whilst the darkcurrent tends to be Arrhenius. The hole mobility was measured for the random domain cell and was found to be faster than 10−4 cm2v−1sec−1 in the mesophases. The cell used for the photocurrent measurements was a sandwich-type one using two ITO glass slides as electrtodes and show rectification behavior for the crystal and the low-temperature mesophase (DLC) in contrast to non-rectification of photocurrent in the high-temperature mesophase (DL). These properties of charge carrier migration as an electronic process are profoundly related to molecular order as well as molecular motions in mesophase.
Study of Electrochemical Deposition of Copper and Microstructure Evolution in Fine Lines
Authors: Grunow Stephan , Diatezua Deda , Seo Soon-Cheon , Stoner Timothy , KaloyerosI Alain E. 
Published: April 2011

ABSTRACTAs computer chip technologies evolve from aluminum-based metallization schemes to their copper-based counterparts, Electrochemical Deposition (ECD) is emerging as a viable deposition technique for copper (Cu) interconnects. This paper presents the results of a first-pass study to examine the underlying mechanisms that control ECD Cu nucleation, growth kinetics, and post-deposition microstructure evolution (self-annealing), leading to the development and optimization of an ECD Cu process recipe for sub-quarter-micron device generations. The influence of bath composition, current waveform, type and texture of Cu seed layer, and device feature size (scaling effect) on the evolution of film texture, morphology, electrical properties, and fill characteristics was investigated using a manufacturing-worthy ReynoldsTech 8″ wafer plating tool. Resulting films were analyzed by X-ray Diffraction (XRD), four-point resistivity probe, Focused-Ion-Beam Scanning Electron Microscopy (FIB-SEM), and Atomic Force Microscopy (AFM). These investigations identified an optimized process window for the complete fill of aggressive device structures with pure Cu with resistivity ∼ 2.0 μΩ-cm and smooth surface morphology.
The Influence of Patterning in Co And Co/Pd Multilayer Structures
Authors: Borca C. N. , Cheng Rui-Hua , Dowben P. A. 
Published: April 2011

ABSTRACTWe are studying ferromagnetic films of cobalt and cobalt - palladium heterostructures fabricated by laser assisted chemical deposition from organometalic compounds. We have developed this one-step deposition technique sufficiently to deposit pure metal features with excellent spatial resolution and in multilayer geometries. From the comparison between the continuous and patterned films we can conclude that the patterning of the films into arrays of discrete micron-scale features has a great influence on the magnetic properties of the films.
Layer-By-Layer Oxidation of Silicon Surfaces
Authors: Watanabe Heiji , Miyata Noriyuki , Ichikawa Masakazu 
Published: April 2011

ABSTRACTLayer-by-layer oxidation of Si(111) and (001) surfaces has been studied by using scanning reflection electron microscopy (SREM). We found that SREM images reveal interfacial structures of the SiO2/Si system. Our results showed that the initial step structure of Si substrates was preserved at SiO2/Si interfaces and that interfacial steps did not move laterally during oxidation. We also observed a periodic reversal of terrace contrast in SREM images during the initial oxidation of Si(001) surfaces. These results indicate layer-by-layer oxidation of Si surfaces, which is promoted by the nucleation of nanometer-scale oxide islands at SiO2/Si interfaces. In addition, we investigated the kinetics of initial layer-by-layer oxidation of Si(001) surfaces. We found that a barrierless oxidation of the first subsurface layer, as well as oxygen chemisorption onto the top layer, occur at room temperature. The energy barrier of the second-layer oxidation was found to be 0.3 eV. The initial oxidation kinetics are discussed based on first-principles calculations. Moreover, we confirmed that the layer-by-layer oxidation of Si surfaces holds true for conventional furnace oxidation.
Two-Band Tunneling Currents and Stress-Induced Leakage in Ultra-Thin SiO2 Films
Authors: Okhonin S. , Ils A. , Bouvet D. , Fazan P. , Guegan G. , Deleonibus S. , Martin F. 
Published: April 2011

ABSTRACTThe conduction band and valence band electron tunneling currents in ultra-thin SiO2 films at the transition from direct to Fowler-Nordheim tunneling regimes are studied. The slopes of the current voltage characteristics agree well with the simulations performed. The Stress-Induced Leakage Current (SILC) behavior is quite similar for both conduction and valence band currents even if the amplitude of the valence band SILC is much lower. We show that a linear dependence exists between the stress-induced interface trap density and both valence and conduction band SILC. A new model of SILC is also proposed.
Low Damage Nitridation of Silicon Oxide Surfaces By Remote-Plasma-Excited Nitrogen
Authors: Saito Yoji , Mori Ukyo 
Published: April 2011

ABSTRACTWe incorporated significant density of nitrogen only near the top surfaces of the thermally grown oxides by the fluorination at room temperature followed by atomic nitrogen treatment around 550°C. Average nitrogen concentration of more than 6 percent was obtained in the nitrided layer with thickness below 1 nm. We fabricated MOS devices using the nitrided oxide films without hydrogenation, and measured capacitance-voltage characteristics. The density of nitridation-induced interface defects in the MOS device was estimated to be below 2×1010 cm−2. The proposed technique identifies a unique process for obtaining high quality ultrathin dielectrics.
Bulk and Surface Electronic Properties of Oxide Dielectrics
Authors: Henrich Victor E. 
Published: April 2011

ABSTRACTThe electronic properties of oxides that are candidates for high-dielectric insulators in ULSI are discussed. The theoretical models that can be used to describe them are compared, and the properties of cation oxidation state and point defects associated with non-stoichiometry in the bulk and on the surface are considered. Metal-oxide surfaces often reconstruct, with the creation of a surface dipole moment The effect of overlayers on metal-oxide surfaces is also discussed.
Transient Diffusion Effects of Sb and B In Si Induced by Medium- and High-Energy Implants of Si+ and As+ Ions
Authors: Lulli G. , Solmi S. , Bianconi M. , Napolitani E. , Carnera A. 
Published: April 2011

ABSTRACTIn this work we investigate the influence of defects injected by ions of different mass and energy on the diffusion of B and Sb markers in bulk Si. MeV (Si or As) ions induce Sb transient enhanced diffusion, whose amount increases with increasing the near-surface vacancy supersaturation generated by the knock-on recoil mechanism. The enhancement effect lasts less than 2 h at 800 °C and less than 10 min at 900 °C. At higher (1000 °C) annealing temperature it appears that the influence of extra-interstitials introduced by the implants comes into play, inducing a retardation in Sb diffusion which is larger for the higher close implant. The effect of vacancy supersaturation observed in medium-energy implanted samples is considerably weaker than the one found in high-energy implanted ones. In the case of B marker high-energy implantation induces moderate enhanced diffusion, much smaller than the one observed -after medium-energy implants.
Nitrogen Implantation and Diffusion in Silicon
Authors: Adam Lahir Shaik , Law Mark E. , Dokumaci Omer , Haddara Yaser , Murthy Cheruvu , Park Heemyong , Hegde Suri , Chidambarrao Dureseti , Mollis Steve , Domenicucci Tony , Dziobkowski Chester , Jones Kevin , Wong Philip , Young Ralph , Srinivasan R. 
Published: April 2011

ABSTRACTNitrogen implantation can be used to control gate oxide thicknesses [1,2]. This study aims at studying the fundamental behavior of nitrogen diffusion in silicon. Nitrogen at sub-amorphizing doses has been implanted as N2+ at 40 keV and 200 keV into Czochralski silicon wafers. Furnace anneals have been performed at a range of temperatures from 650°C through 1050°C. The resulting annealed profiles show anomalous diffusion behavior. For the 40 keV implants, nitrogen diffuses very rapidly and segregates at the silicon/ silicon-oxide interface. Modeling of this behavior is based on the theory that the diffusion is limited by the time to create a mobile nitrogen interstitial.
Manufacturable Large Area CdS Thin Films for Solar Cell Applications Monitored with Optical Emission Spectroscopy
Authors: Wang L. , Eisgruber I. , Hollingsworth R. , DeHart C. , Wangensteen T. , Treece R. E. , Bhat P. , Shafarman W. N. , Birkmire Robert W. , Gillespie T. J. 
Published: April 2011

ABSTRACTManufacturable, sputtered, device-quality, CdS thin films are reported for high efficiency solar cell applications. The sputtering plasma is monitored during deposition using optical emission spectroscopy. Optical emission spectroscopy (OES) is commonly used as an end point detector in plasma etching processes, where the disappearance of the etch product wavelength signature provides an unambiguous indication of completion. OES is only now beginning to be examined for controlling deposition processes, primarily because the dependence between OES signal and film properties can frequently be a quite complex function of the electron and gas densities, the emitting species concentration, the electron impact excitation cross section, the electron energy distribution function, and the probability of inelastic collisions between plasma species. OES monitoring during CdS sputtering allows accurate determination of deposition rate. Both Cd and S emission peaks can be identified, allowing tracking of the results of preferential sputtering. The OES output has been tied directly into the chamber controls, resulting in automatic closed-loop control of deposition rate. The resulting CdS films are device-quality and well-suited to large-scale manufacturing. A photovoltaic efficiency of 12.1 % was obtained from sputtered CdS on CIGS absorber, compared to 12.9% for the traditional, but less manufacturable, chemical bath deposited CdS on the same batch of CIGS. The sputtering technique has many advantages over other deposition techniques, such as easy scaleablity to large areas, simple process control, compatibility with in-line manufacturing of layered devices and low cost. RF, or lower-cost pulsed DC, sputtering power supplies can be used with comparable deposition rates. The structure, optical, and electrical properties of the sputtered CdS thin films have been characterized.
Martensitic Nucleation in Small ZrO2 Particles
Authors: Chen I-Wei , Chiao Yi-Hung 
Published: April 2011

AbstractSmall ZrO2 particles were studied by in-situ transmission electron microscopy and the types of events which led to martensitic nucleation were recorded. These metastable particles were single crystals of several hundred nanometers size and were supported on a carbon thin film but were otherwise free from any constraint. At room temperature, they are more than 1200°C below the equilibrium temperature. After dislocation loops were injected in-situ into the originally defect-free particles, a critical loop size was found beyond which the particle transformed spontaneously. It was also observed that Hertzian contacts between two particles led to martensitic nucleation and spontaneous transformation. These results were satisfactorily rationalized by ab-initio theoretical analysis.
Kinetics of Metallic Glass Formation by Solid State Reactions
Authors: Samwer K. , Schröder H , Moske M. 
Published: April 2011

AbstractMetallic glass formation by solid state reactions has been observed in multilayer Zr-Co diffusion couples. The kinetics of the reaction are limited by the diffusion of the Co-atoms in the growing amorphous layer, at least for longer times, as shown by cross-sectional transmission electron microscopy and resistance measurements. The latter one provides the interdiffusion constant and the activation energy of about 1.1 eV. Deposition of the crystalline layers at 77 K results in an enhanced amorphization process in the first stage of the reaction and gives preliminary answers about the nucleation of the amorphous phase.
The Melting of Amorphous Si
Authors: Poate J. M. , Peercy P. S. , Thompson M. O. 
Published: April 2011

AbstractThe prediction by Turnbull and his colleagues that amorphous Si and Ge undergo first order melting transitions at temperatures Taℓ substantially beneath the crystalline melting temperature Tcℓ has stimulated much work. Structural, calorimet:ic and transient conductance measurements show that, for Si, Tcℓ – Taℓ lies in the range 225–250°K. Studies of the pulsed laser melting of the Si amorphous-liquid transition have resulted in the following findings, an estimate of the undercooling rate of 15°K/m/sec, an understanding of the mechanism mediating explosive crystallization, the formation of internal melts and segregation of dopants at the liquid-amorphous interface.
Ultrafast Electron Dynamics in Ge Quantum Dots
Authors: Stella A. , Tognini P. , De Silvestri S. , Nisoli M. , Stagira S. , Cheyssac P. , Kofman R. 
Published: April 2011

ABSTRACTAn analysis of the ultrafast response of Ge quantum dots, with average radii of 4 nm and 16 nm, is reported here. Pump and probe experiments allowed investigation of the wavelength region between 450 and 750 nrm, characterized by the absorption peaks due to the E, and E1+Δ1 interband transitions. Two different time regimes have been identified: a first one (τ ≤ 1 ps) associated with pump-induced conduction band filling in the τ-L direction in the Brillouin zone; a second one (τ up to 100 ps) associated with band gap renormalization caused by the carrier interaction in the conduction band. Quantum confinement effects show up in terms of sizedependent blueshift of the E1+Δ1 spectral feature.
Strain in Coherent Ge Quantum Islands on Si Measured by Transmission Electron Microscopy
Authors: Liu Chuan-Pu , Miller Peter D. , Henstrom William L. , Gibson J. Murray 
Published: April 2011

ABSTRACTWe describe a quantitative method for measuring the strain in small islands, and show results for coherent Ge islands on Si. The method uses dark field images from backside thinned samples in the transmission electron microscope. We show that no independent strain models are needed in the measurement, which employs an excellent “abrupt displacement” approximation. Results show that the strain in Ge domes is higher than in pyramids as expected.
Luminescent Characteristics of Pulsed Laser Deposited Epitaxial Eu-Doped Y2O3 Films
Authors: Kumar D. , Cho K. G. , Chen Zhang , Craciun V. , Holloway P. H. , Singh Rajiv K. 
Published: April 2011

AbstractThe growth, structural and cathodoluminescent (CL) properties of europium activated yttrium oxide (Eu:Y2O3) thin films are reported. The Eu:Y2O3 films were grown in-situ using a pulsed laser deposition technique. Our results show that Eu:Y2O3 films can grow epitaxially on (100) LaAlO3 substrates under optimized deposition parameters. The epitaxial growth of Eu:Y2O3 films on LaAlO3, which has a lattice mismatch of ∼ 60 %, is explained by matching of the atom positions in the lattices of the film and the substrate after a rotation. CL data from these films are consistent with highly crystalline Eu:Y2O3 films with an intense CL emission at 611 nm.