bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fatal equine meningoencephalitis in the United Kingdom caused by the panagrolaimid nematodeHalicephalobus gingivalis: Case report and review of the literature
Authors: HERMOSILLA C. , COUMBE K. M. , HABERSHON‐BUTCHER J. , SCHÖNIGER S. 
Published: March 2011

SummaryA fatal case of eosinophilic and granulomatous meningoencephalitis caused by the free‐living panagrolaimid nematodeHalicephalobus gingivalisis reported in a 10‐year‐old Welsh gelding in the United Kingdom. Clinical examination first revealed behavioural abnormalities which rapidly progressed to severe ataxia, reduced mentation status and cranial nerve signs. Despite symptomatic treatment no amelioration of neurological signs was achieved and the horse was subjected to euthanasia. A completepost mortemexamination revealed eosinophilic and granulomatous meningoencephalitis mainly affecting the cerebellum and brain stem with intralesional adult nematodes, larvae and eggs. There was also eosinophilic meningitis of the cervical spinal cord. The intralesional nematodes were morphologically consistent with the panagrolaimid nematodeH. gingivalis. Although infection by this facultative neurotropic parasite is extremely rare, it needs to be considered in the differential diagnosis of central nervous signs in horses and, in particular, other equine helminthic infection of the central nervous system. This fatal case is unusual since lesions were locally very extensive and the nematodes did not colonise haematogenously to other organs as seen often in equine halicephalobosis. As the taxonomy ofH. gingivalishas changed and some recent reports in the literature still refer to this species asMicronema deletrixorHalicephalobus deletrix, we here provide a short update of the species and some insights on the order Tylenchida, which contains free‐living nematodes with parasitic tendencies.
Theoretical Models of Schottky Barriers
Authors: Schluter M. 
Published: March 2011

ABSTRACTA review is presented in which existing theories of the formation of Schottky barriers are analyzed. The list includes macroscopic dielectric approaches and various microscopic quantum mechanical treatments. The central role of interface states and their different physical origins are assessed. Simple concepts, able to predict general trends in barrier heights, are examined along with detailed microscopic theories applied to individual contacts.
New Developments in the Defect Structure of Implanted Furnace-Annealed Silicon on Sapphire
Authors: Richmond Eliezer Dovid , Knudson Alvin R. , Magee Tom J. 
Published: March 2011

ABSTRACTThe structural defect properties of silicon on sapphire (SOS) are investigated with transmission electron microscopy and Rutherford backscattering. The results for as-grown SOS films are compared with SOS films which have been implanted with 1016 Si+ ions cm− 2 at an energy of 170 keV and annealed at 600°C (1 h) and 1000°C (18 h). The regrowth proceeds from the silicon surface even though it is noncrystalline as determined by reflection high energy electron diffraction. The structural defects consist of stacking faults, microtwins and dislocations. The stacking faults and microtwins show a dramatic reduction with processing. The nature of the structural defects at the interface after implantation and annealing is reported here for the first time. It is different from the bulk of the silicon film and consists of a layer of dislocation loops of various sizes and short dislocation lines which follow the interface and curve upwards. This behavior is analogous with the secondary defects generated in self-implanted bulk silicon. Suggestions, based on results from bulk silicon implantation, are made for optimizing the ion implantation furnace annealing process.
Ion Beam Deposition: Damage and Epitaxy
Authors: Armour D G 
Published: March 2011

ABSTRACTThe bombardment of solid surfaces with ions in the energy range below about 150 eV, depending on the ion-substrate combination, results in a net growth of material on the surface. An ion beam facility capable of producing highly uniform, low energy beams of current densities in the range 10−2 to 1 Am−2 has been developed to study the potential of this growth technique for the fabrication of thin epitaxial films at low temperatures.The energy deposition associated with ion bombardment, which is considered to be responsible for the low temperature epitaxy capability, can also cause atomic displacements on the surface and near-surface regions of the substrate during initial growth and in the growing film. A study of the growth processes thus requires investigation of the damaging effects of low energy ion bombardment. In the present paper, fundamental aspects of the implantation and deposition of materials using very low energy ions will be discussed.
Molecular Dynamics Simulation of Sputtering with Mmany-Body Interactions
Authors: Lo Davy Y. , Tombrello Tom A. , Shapiro Mark H. , Harrison Don E. 
Published: March 2011

ABSTRACTMany-body forces obtained by the Embedded-Atom Method (EAM) [41 are incorporated into the description of low energy collisions and surface ejection processes in molecular dynamics simulations of sputtering from metal targets. Bombardments of small, single crystal Cu targets (400–500 atoms) in three different orientations ({100}, {110}, {111}) by 5 keV Ar+ ions have been simulated. The results are compared to simulations using purely pair-wise additive interactions. Significant differences in the spectra of ejected atoms are found.
Microstructure and Composition of Surface Layers Formed by Ion Implantation of Nitrogen in High-Purity Aluminum
Authors: Mccune Robert C. , Donlon W. T. , Plummer H. K. , Toth L. , Kunz F. W. 
Published: March 2011

ABSTRACTSurface layers with overall thickness <∼300 nm were produced by ion implantation of N+ or N2+ at energies of 50 or 100 keV in 99.99% pure aluminum. These surfaces were characterized by scanning and transmission electron microscopy, Auger electron spectroscopy, Rutherford backscattering, nuclear reaction analysis and particle-induced X-ray analysis. At doses above 2×1017 N2/cm2 , blistering of the surfaces was observed along with a reduction in the extent of the coulometric dose retained by the material. Oxygen is believed to be introduced into the near-surface region by a process of reaction and ion-beam mixing, as well as possible CO contamination of the beam. A phase, isostructural with AlN, forms semi-coherently with parent aluminum grains, however, some fraction of the metallic aluminum phase remains in the reaction layer, even at overall nitrogen contents which exceed the stoichiometry of AlN.
Ion Implantation Damage in Aluminum Studied by Quantitative Electron Chanelling and Tem.
Authors: Vardiman Ronald G. 
Published: March 2011

ABSTRACTElectron chanelling linewidth changes in aluminum have been measured as a function of dose for boron and aluminum ion implantation. Weak beam TEM observations assist interpretation of the results by showing the nature and degree of the damage. For self implantation, a linear relationship between dose, linewidth, and dislocation density has been found up to 3×1017ions/cm2. For boron implantation, a new point-like defect appears at the higher boron concentrations, giving a much slower increase of chanelling linewidth with dose above l×1016 ions/cm2. Boron interaction with the damage stabilizes higher damage acumilations than for sel f-i mpl antati on.
Nitrogen and Carbon Solute Redistribution During High Fluence Nitrogen Implantation into Iron
Authors: Ehni P. D. , Singer I. L. , Hues S. M. 
Published: March 2011

ABSTRACTModel solute distribution studies have been performed in N-implanted Fe. Concentration-verses-depth profiles have been determined by secondary ion mass spectroscopy for Fe implanted to low fluences with isotopes 13C at 190keV and 15N at 180keV followed by 14N to high fluences. At N fluences greater than 2.5 × 1017 /cm2 dramatic changes in the 13C and 15N profiles are observed. It is proposed that these changes are caused by the lattice dilation due to precipitation of iron nitrides.
Enhanced Oxidation of TiSi2 Films by As+ Implantation
Authors: Holland O. W. , Fathy D. 
Published: March 2011

ABSTRACTThe influence of As+-ion implantation on the oxidation of TiSi2 films is investigated. It will be shown that implantation leads to a greatly increased rate of oxidation in a dry O2 ambient. Low-temperature oxidation of the implanted films not only results in substantial oxidation of the films, but completely alters the films' morphology. Different implantation techniques were used to isolate the effects of ion-induced damage from chemical effects, so that each could be separately studied. It will be shown that neither chemical nor damage effects are able, by themselves, to account for the enhanced oxidation. Rather, a model is proposed to explain the role of implantation in the oxidation process which depends on a synergistic relation between these two effects.
Capacitance Spectroscopy of Schottky Diodes Formed on Ion-Etched GaAs
Authors: Sen S. , Cole E. D. , Burton L. C. 
Published: March 2011

ABSTRACTDLTS and low frequency capacitance measurements were made on Schottky diodes formed on Ion-beam etched (IBE) GaAs surfaces. Ion bombardment causes strong low frequency capacitance dispersion, increasing with ion energy. This is attributed to a thin, heavily damaged region, with a trap density in excess of 1017 per cm3. Such dispersion disappears under weak reverse bias and at reduced temperatures. These and other measurements are consistent with a lumped R-C model having components representing the top damaged layer, the underlying space-charge region, and shunt resistance to the ohmic contact.
Synthesis of Buried Silicon Compounds Using Ion Implantation
Authors: White Alice E. , Short K. T. , Dynes R. C. , Gibson J. M. , Hull R. 
Published: March 2011

ABSTRACTIon implantation is widely used for doping semiconductors at low concentration, but, with the advent of a new generation of high current implanters, synthesizing new materials rather that simply doping them has become feasible. This technique has been successfully applied to fabricating silicon-on-insulator (SOI) structures with oxygen and nitrogen for several years. Since we are interested in understanding the mechanisms of formation of these layers, we have concentrated on sub-stoichiometric implantation doses of oxygen where it is easier to observe the coalescing layer. In order to determine whether this process of compound formation is more general, our studies were expanded to include implantation of the transition metals. Here, elevated substrate temperatures are necessary to minimize Si surface damage. The resulting disilicide layers are of remarkably high quality: they are single crystals in registry with the silicon wafer and they have better residual resistivities than comparable UHV-reacted silicides.
Optical Waveguide Formation by Ion Implantation of Ti or Ag
Authors: Poker D. B. , Thomas D. K. 
Published: March 2011

ABSTRACTIon implantation of Ti into LINbO3 has been shown to be an effective means of producing optical waveguides, while maintaining better control over the resulting concentration profile of the dopant than can be achieved by in-diffusion. While undoped, amorphous LiNbO3 can be regrown by solid-phase epitaxy at 400°C with a regrowth velocity of 250 Å/min, the higher concentrations of Ti required to form a waveguide (∼10%) slow the regrowth considerably, so that temperatures approaching 800°C are used. Complete removal of residual damage requires annealing temperatures of 1000°C, not significantly lower than those used with in-diffusion. Solid phase epitaxy of Agimplanted LiNbO3, however, occurs at much lower temperatures. The regrowth is completed at 400°C, and annealing of all residual damage occurs at or below 800°C. Furthermore, the regrowth rate is independent of Ag concentration up to the highest dose implanted to date, 1 × 1017 Ag/cm2. The usefulness of Ag implantation for the formation of optical waveguides is limited, however, by the higher mobility of Ag at the annealing temperature, compared to Ti.
Defect Dynamics in Amorphous Silicon – the Recrystallization Process
Authors: Pantelides Sokrates T. 
Published: March 2011

ABSTRACTThe mechanism that underlies the recrystallization of amorphous silicon tas not been established. It is generally argued, however, that the rearrangement of the network occurs through the breaking of bonds or the introduction of vacancies and that this step is responsible for the observed activation energy (∼2.5 eV). It is suggested here that the rearrangement of the network is accomplished through the migration of intrinsic overcoordination defects (“floating bonds”) and that this process has a small activation energy (∼0.4 eV). The observed large activation energy is actually due to a reaction that inhibits recrystallization. This reaction may be the elimination of preexisting dangling bonds.
Ion Beam Induced Regrowth in GaAs
Authors: Johnson S. T. , Williams J. S. , Nygren E. , Elliman R. G. 
Published: March 2011

ABSTRACTIon implanted, amorphous layers on (100) GaAs have been recrystallised epitaxially by 1.5 MeV Ne+ irradiation at temperatures between 75°C and 135°C. The extent of regrowth essentially increases linearly with ion fluence in the early stages of crystallization and the process is characterized by an activation energy of 0.16eV, about an order of magnitude lower than that for thermal - only epitaxy. Beam annealing produces dislocations in the underlying GaAs crystal, the density of which increases with depth up to the Ne+ ion range.
Femtosecond Carrier Dynamics in Semiconductors and Metals
Authors: Lin Wei Zhu , Schoenlein Robert W. , Brorson Stuart D. , Ippen Erich P. , Fujimoto James G. 
Published: March 2011

ABSTRACTWe describe investigations of carrier dynamics in GaAs and AlGaAs semiconductors and thin gold films using femtosecond optical techniques. Transient absorption saturation measurements in semiconductors permit an investigation of the fundamental scattering processes of optically excited carriers. Measurements of energy relaxation provide evidence for transient nonthermal carrier distributions. Studies in metals allow an investigation of nonequilibrium electron and phonon effects since the electrons are decoupled from the lattice on a femtosecond time scale. Nonequilbrium temperatures and energy transport in the electron gas have been observed.
Picosecond Laser-Induced Solid-Liquid Phase Transformations in Gallium Arsenide and Silicon
Authors: Danielzik B. , Harten P. , Sokolowski-Tinten K. , Linde D. von der 
Published: March 2011

ABSTRACTMelt-in velocities of picosecond laser-heated Si and GaAs were obtained from optical reflectivity measurements. We observed a velocity increase from about 100 m/s near the melting threshold to many hundred m/s at higher fIuences. With a new technique for picosecond time-resolved observation of atomic desorption we have been able to resolve the evaporation of Ga.
Effect of Density Change on Rapid Liquid-Solid Interface Kinetics and Heat Flow
Authors: Richards Peter M. 
Published: March 2011

ABSTRACTConsequences of the need to transport density to or from a fast-moving liquid-solid interface are examined. There can be a severe limitation of the freezing velocity and a change in the amount of heat which must be conducted. The latter effect produces a net latent heat which can be significantly different from the equilibrium value and even change sign.
Excimer Laser Mixing of Titanium Layers on AISI 304 Stainless Steel
Authors: Jervis T. R. , Nastasi M , Zocco T. G. 
Published: March 2011

ABSTRACTWe have used excimer laser radiation to mix single layers of Ti directly on annealed substrates of 304 stainless steel. This process produces much thicker surface alloy layers and is much faster than ion mixing techniques. Liquid state diffusion results in mixed layers of the order of 1.0 μm thick from 0.5 μm Ti overlayers. In single pulse experiments, fluences of up to about 4 times melt threshold could be used before ablation occurred. The fluence in these experiments determines the melt duration and therefore the amount of mixing. In order to achieve greater mixing without ablation of the surface, multiple pulses at lower fluence were used. Profiles of laser mixed surface layers and microstructural characterization of the layers are presented.
Threshold for Single Excimer Laser Pulse Backside Removal of Thin Metal Films from Optical Quartz
Authors: Baseman R. J. , Andreshak J. C. 
Published: March 2011

ABSTRACTThe minimum energy in a 248 nm, 25 ns long excimer laser pulse required to remove thin Au and Cr films from optical quartz has been measured. Heating of the films by the laser has been modelled with a finite element calculation. Assuming that at threshold, all of the laser energy contributes to film removal, the calculations show that the gold films are removed when the heated gold surface reaches the atmospheric boiling point, and that temperatures well in excess of the atmospheric boiling point are required to remove the Cr films, with the required temperatures increasing with film thickness.
Interpretation of Time-of-Flight Distributions Resulting from Pulsed Laser-Induced Desorption
Authors: Buck M. , Hess P. 
Published: March 2011

ABSTRACTTime-of-flight (TOF) experiments were performed to study the desorption of trans-l,2-dichlorocyclohexane molecules from molecular films condensed on a quartz-crystal microbalance at 77 K. The wavelength dependence of the desorption signal was investigated by resonant excitation of the internal vibrational mode of the molecule in the 10 μm region with a pulsed line-tunable TEA CO2 laser. The TOF temperatures showed the same spectral dependence as the optical absorption coefficient. The TOF distributions were narrower than Maxwellian distributions for multilayer desorption yields and approached Maxwellian distributions for submonolayer desorption yields. A saturation behavior was found at high laser intensities, indicating that the kinetic energy of the desorbing molecules is limited to a maximum value.
Nmos Transistors Fabricated by Simultaneous Laser-Assisted Crystallization and Diffusion on Silicon on Electro-Optic PLZT
Authors: Wang J. H. , Lin T. H. , Esener S. C. , Dasgupta S. , Lee S. H. 
Published: March 2011

ABSTRACTSimultaneous CW laser assisted crystallization and diffusion for fabricating NMOS transistors on Si/SiO2/PLZT is presented. Hall effect measurement (mobility 74cm2V−1sec×1019cm−3 of phosphorus dopping), crystal delineation (grain size 50×30μm) and Raman spectroscopy (stress 6.0×109dynescm−2) indicated that good quality doped silicon crystal film can be produced with this method. NMOS transistors fabricated by this technology show good performances such as high breakdown voltage (45 V), small leakage current (2 nA/μm), reasonable channel carrier mobility (140cm2V−1−1) and photosensitivity (1.5 A/W).
Arsenic Redistribution and Outdiffusion in Implanted Czochralski-Grown P-Type Silicon During Rapid Thermal Annealing
Authors: Chaussemy G. , Canut B. , Kumar S. N. , Barbier D. , Laugier A. 
Published: March 2011

ABSTRACTThe effects of the implantation parameters (dose and energy) on the Arsenic redistribution and outdiffusion rate in (100) p-type silicon, after 7–12 s Rapid Thermal Annealing in the 1100–1200°C temperature range have been investigated. Four doses ranging from 2×1014 to l×1016 cm−2, and As+ energies between 70 and 170 keV, have been studied. The experimental diffusion profiles obtained from the SIMS measurements, in complement with the RBS results, were modelled using the one dimensional Fick's equation with semi-infinite boundary conditions, using a concentration and temperature dependent diffusion coefficient D(C, T). The As diffusivity was classically attributed to As+V0, As+V−, and As+V − pairs with the related diffusion coefficients taken from the literature. A relatively good description of the As redistribution was obtained without introducing any transient or SPE effects.
Redistribution of Dopant and Impurity Concentrations During the Formation of Uniform Wsi2 Films by RTP
Authors: Siegal Michael P. , Santiago Jorge J. 
Published: March 2011

ABSTRACTSecondary ion mass spectroscopy has been used to study the effects of rapid thermal processing on the formation of tetragonal tungsten disilicide thin films on Si(100), p-type 5 Omaga;, cm wafers. The substrates were chemically etched, followed by an RF sputter depostion of 710Å W metal. The samples were then fast radiatively processed in an RTP system for time intervals ranging from 15 to 45 seconds at high temperature (∼1100°C) under high vacuum.The redistribution of the boron dopant concentration profile is studied and shows that boron moves from the Si-substrate into the growing Wsi2 film, eventually escaping into the vacuum. Oxygen is the major impurity in these samples and its removal from the interface has been shown to improve the quality of the silicide film. Trace quantities of F, Cl, Na, K, C and Cr have also been detected.
Millisecond Duration Annealing of Boron Implants in Silicon
Authors: Smith D. A. , McMahon R. A. , Ahmed H. , Godfrey D. J. 
Published: March 2011

ABSTRACTA dual electron beam machine has been used to anneal boron implanted layers in order to study the diffusion and activation behaviour over a wide range of doses. The annealed implants have been characterized by spreading resistance profiling and secondary ion mass spectroscopy (SIMS). Carrier concentration profiles show that millisecond duration anneals can activate boron implants. A boron dose of 1E16 ions/cm2 was annealed to give a sheet resistance of 30 Ωsq with 40% of the implant activated. The SIMS technique showed there were no significant differences between the atomic profiles of the as-implanted samples and specimens subjected to a millisecond anneal or to a low temperature 850°C rapid isothermal anneal for 10s.
Shallow Junctions Formed by the Thermal Redistribution of Implanted Arsenic into TiSi2
Authors: Cao D. X. , Harrison H. B. , Reeves G. K. 
Published: March 2011

ABSTRACTFollowing the implantation of arsenic into titanium disilicide films on p type silicon, Rutherford backscattering has shown that rapid thermal vacuum processing (RTVP) causes the arsenic to diffuse toward the silicide/silicon interface, with an accumulation at the interface and with a sharp shallow diffusion into the silicon. The effect of the implant and anneal on the sheet resistance of the silicide and underlying silicon have been investigated’ and it is shown that anneal times of thirty seconds at 900 °C produce acceptable shallow junctions suitable for device type applications without significant deterioration in silicide electrical or physical properties.