bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ion Beam Enhanced Formation and Luminescence of Si Nanoclusters from a-SiOx
Authors: Sun Yohan , Seo Se-Young , Shin Jung H. , Kim T. G. , Whang C. N. , Song J. H. 
Published: April 2011

AbstractThe effect of ion beams on the formation of Si nanoclusters from a-SiOx films and their luminescence properties is investigated. a-SiOx films with Si content ranging from 33 to 50 at. % were deposited by Electron Cyclotron Resonance Plasma Enhanced Chemical Vapor Deposition (ECR-PECVD) of SiH4 and O2. Prior to anneal, some samples were implanted with 380 keV Si to a dose ranging from 5.7 × 1014 cm−2 to 5.7 × 1016 cm−2. All films were rapid thermal annealed under flowing Ar environment, and hydrogenated after anneals to passivate defects and to enhance the luminescence of Si nanoclusters. For films with Si content less than 40 at. %, ion beam slightly reduces the photoluminescence (PL) intensity and induces a slight blueshift of the luminescence. For films with Si content greater than 40 at. %, ion beam greatly increases the PL intensity. Based on the effect of the ion beams dose and the ion specie, we propose that ion beams damage greatly promotes nucleation of small Si clusters from the a-SiOx matrix.
Coordination structure of implanted manganese ions in silica glass
Authors: Fukumi Kohei , Chayhara Akiyoshi , Kageyama Hiroyuki , Kadono Kohei , Kitamura Naoyuki , Mizoguchi Hirohsi , Horino Yuji , Makihara Masaki 
Published: April 2011

Abstract180 keV Mn+ ions were implanted in silica glass at doses ranging from 1×1016 to 2×1017 ions/cm2 at room temperature. The coordination structure of implanted Mn atoms was studied by X-ray absorption spectroscopy. It was found that Mn atoms were mainly coordinated by O atoms in silica glasses as-implanted at doses lower than 5×1016Mn+ions/cm2. The Mn-O bond distance was 2.07 Å and the coordination number was 4.3 in average. Mn atoms were mainly coordinated by Mn and O atoms in the glasses as-implanted at doses higher than 1×1017 Mn+ions/cm2. In all the glasses, Mn atoms which are coordinated by O atoms were present as divalent state. After heating at 700 °C in air, Mn atoms were present as trivalent state and tended to form oxide crystals.
Nanoparticles of metallic Cobalt and Nickel prepared by ion implantation into SiO2
Authors: Cíntora-González O. , Estournès C. , Muller D. , Richard-Plouet M. , Traverse A. , Guille J. L. , Grob J.J. 
Published: April 2011

AbstractThe structural and magnetic properties of nano-sized particles of transition metals (Co and Ni) implanted into amorphous SiO2 are investigated. The SiO2 substrates used were as grown on a silicon (100) wafer under wet O2 atmosphere. The metals were implanted as singly charged atoms energized to 30 or 160 keV. Transmission Electron microscopy (TEM) observations and X-ray absorption spectroscopy (XAS) show that M+ implantation results in the formation of metallic nanoparticles at the vicinity of the surface whereas oxide particles (< 1 nm) are formed in a deeper region. After thermal treatment under hydrogen, TEM evidences the disappearance of the oxide region and an increase in the size of the metallic particle. XAS shows that cobalt and nickel are entirely in the metallic form and saturation magnetization becomes close to the theoretical value.
Secondary Ion Mass Spectrometry with Gas Cluster Ion Beams
Authors: Toyoda Noriaki , Matsuo Jiro , Aoki Takaaki , Chiba Shunichi , Yamada Isao , Fenner David B. , Torti Richard 
Published: April 2011

AbstractSecondary Ion Mass Spectrometry (SIMS) with Gas Cluster Ion Beams (GCIB) was studied with experiments and molecular dynamics (MD) simulations to achieve a high-resolution depth profiling. For this purpose, it is important to prevent both ion-mixing and the surface roughening due to energetic ions. As the Ar cluster ion beam shows surface smoothing effects and high secondary-ion yield in the low-energy regime, the cluster ion beam would be suitable for the primary ion beam of SIMS. From MD simulations of Ar cluster ion impact on a Si substrate, the ion-mixing is heavier than for Ar monomer ions at the same energy per atom, because the energy density at the impact point by clusters is extremely high. However, the sputtering yields with Ar cluster ions are one or two orders of magnitude higher than that with Ar monomer ions at the same energy per atom. Comparing at the ion energy where the ion-mixing depths are the same by both cluster and monomer ion impacts, cluster ions show almost ten times higher sputtering yield than Ar monomer ions. Preliminary experiment was done with a conventional SIMS detector and a mass resolution of several nm was achieved with Ar cluster ions as a primary ion beam.
Buried Oxide Precipitates In A Si Wafer Due to He ION Implantation and High-Temperature Oxidation
Authors: Nakashima Sadao , Nakata Jyoji , Hayashi Junzou , Imai Kazuo 
Published: April 2011

AbstractA new method of producing a buried oxide is proposed. It involves implanting a silicon wafer with helium rather than oxygen ions and then subjecting it to high- temperature oxidation. The voids formed by helium ion implantation and subsequent annealing enhance the diffusion of oxygen atoms into the silicon. The oxygen atoms cause thermal oxide to grow at the void/silicon interface and transform the voids into buried oxide precipitates. Auger electron spectroscopy revealed that the total number of oxygen atoms in the precipitates was 9.3 × 1016 cm−2 and that the peak value of oxygen atom concentration in the wafer was approximately 25%.
Cu gettering in Si cavities observed by Positron Annihilation Doppler Broadening
Authors: Schut H. , van Veen A. , Eijt S.W.H. 
Published: April 2011

AbstractIn this study we present the results of Positron Beam Annihilation (PBA) experiments on the gettering of copper in Cz-Si implanted with 33 keV He+ ions with doses ranging from 0.5 to 3× 1016cm−2 followed by an anneal treatment at 1100 K under N2 ambient. For the higher doses this yields a sub-surface layer containing nanometer sized cavities. Copper is introduced into these cavities by diffusing from the backside of the wafer at 1000 K, again under N2 ambient. Mapping of the S and W Doppler broadening parameters, with the implantation dose as running parameter, shows the formation of cavities. After the Cu in-diffusion the change in the values of the characteristic S-W cluster points clearly demonstrates the arrival of Cu at the internal surface of the cavities.
Relating Nanostructures to Mechanical Properties in Ion-Implanted Materials
Authors: Follstaedt David M. , Knapp James A. , Myers Samuel M. , Petersen Gary A. 
Published: April 2011

AbstractIon implantation was used to form high densities (~1019 /cm3) of small oxide precipitates in Ni in order to investigate the strength mechanism produced by such highly refined structures. Nanometer-size precipitates of Al2O3 and NiO are found to block dislocation motion in the Ni matrix, producing yield strengths up to 4.6 GPa, more than twice that of hardened bearing steel. Dispersion strengthening theory, developed for micrometer-size precipitates and spacings, was found to account quantitatively for the yield strengths produced by nanometer-size oxides as well. Nanoindentation plus finite-element modeling was used to quantify the mechanical properties of implanted metal layers, and was extended to examination of amorphous Si layers formed by self-ion implantation. The amorphous phase was found to have a yield strength of 4.45 ± 0.20 GPa, Young's modulus of 144 ± 7 GPa, and hardness of 10.3 ± 0.4 GPa. The modulus and hardness are reduced by 10% and 15%, respectively, from those of crystalline Si.
Ar Cluster Ion Bombardment Effects on Semiconductor Surfaces
Authors: Seki Toshio , Tsumura Kazumichi , Aoki Takaaki , Matsuo Jiro , Takaoka Gikan H. , Yamada Isao 
Published: April 2011

AbstractNew surface modification processes have been demonstrated using gas cluster ion irradiations because of their unique interaction between cluster ions and surface atoms. For example, high quality ITO films could be obtained by O2 cluster ion assisted deposition at room temperature. It is necessary to understand the role of cluster ion bombardment during film formation for the further developments of this technology. Variable Temperature Scanning Tunneling Microscope (VT-STM) in Ultra High Vacuum (UHV) allows us to study ion bombardment effects on surfaces and nucleation growth at various temperatures.The irradiation effects between Ar cluster ion and Xe monomer ion were compared. When a Si(111) surface with Ge deposited to a few Å was annealed to 400°C, it was observed that many islands of Ge were formed. The surface with the Ge islands was irradiated by these ions. In the STM image of cluster-irradiated surface, large craters with diameter of about 100 Å were observed, while only small traces with diameter of about 20 Å were observed in monomer-irradiated surface. The number of Ge atoms displaced by one Ar cluster ion impact was much larger than that by one Xe ion impact. This result indicates that Ar cluster ion impacts can enhance the physical modification of Ge islands. When the sample irradiated with Ar cluster was annealed at 600°C, the hole remained, but the outer rim of the crater disappeared and the surface structure was reconstructed at the site of the rim. The depth of damage region in the target became shallower with decrease of the impact energy. These results indicate that low damage and useful surface modification can be realized using the cluster ion beam.
Finite Element Modeling of Nanoindentation Measurements of Crystalline and Amorphous Si
Authors: Knapp J. A. , Follstaedt D. M. , Myers S. M. , Petersen G. A. 
Published: April 2011

ABSTRACTNanoindentation testing of amorphous Si layers, formed by self-ion implantation, has been performed, and their mechanical properties compared to crystalline Si. The data was analyzed using finite element modeling of the indentation measurement, allowing the properties of the thin amorphous layers to be separated from those of the underlying material. By modeling the materials as isotropic, elastic-plastic solids with the Mises yield criterion, the amorphous Si is shown to have a hardness about 15% lower than crystalline Si and an elastic modulus about 10% lower. Electron and atomic force microscopies of the indents indicate that the amorphous Si does not undergo phase changes during indentation, and that it may be somewhat more ductile than crystalline Si.
Thermomechanical Formation an Thermal Sensing of Nanometer-Scal Indenatations in PMMA Thin Films for Parallel and Dense AFM Data Storage
Authors: Cross Graham L.W. , Despont Michel , Drechsler Ute , Dürig Urs T. , Rothuizen Hugo , Binnig Gerd K. , Vettiger Petr , King William P. , Goodson Kenneth E. 
Published: April 2011

ABSTRACTThermomechanical writing occurs as Joule-heated, cantilevered tips imprint nanometer-scale inden (bits) in a 50-nm-thick polymer (PMMA) film. Thermal data reading incorporates the same cantilevers operated in a mode to detect a temperature change when a tip follows the contour of a previously written bit. Binnig et.al [1] demonstrated single-cantilever writing and rading density at 400 Gbit/in2. A micromachined 32 × 32 cantilever array has been fabricated [2] and has demonstrated parallel read/write operation at 150 Gbi/in in2 [3]. Although much progress has been made to develop a thermomechanical data storage device [4], the fundamental process of thermomechanical storage processes by applying atomic force microscope (AFM)-based force detection during thermal operation. We examined the thermomechanics of polymer indentation with respect to time and temperature of interaction. This work impacts the operation of AFM cantilevens for combined thermal writing and reading and understnding of fundamental polymer mesoscopic transport.
Modulus Determination of Polymer Matrix Composites: Comparison of Nanoindentation and Dynamic Mechanical Analysis
Authors: Grunlan Jaime C. , Rowenhorst David , Francis Lorraine F. , Gerberich William W. 
Published: April 2011

ABSTRACTThe results of modulus measurements, on carbon black-filled poly(N-vinylpyrrolidone), using dynamic mechanical analysis and nanoindentation were compared. It was shown that beyond the critical pigment volume concentration for this composite system (∼ 25 vol% carbon black), the storage modulus, obtained with dynamic mechanical analysis, decreased with increasing filler concentration. This dropping modulus was due to porosity that developed in the composite films when the critical pigment volume concentration had been exceeded. Elastic modulus obtained with nanoindentation showed the opposite trend, with modulus increasing with additional carbon black loading. An analysis of the method used to calculate modulus based upon indentation data was performed and a mechanism was proposed to explain the disparity between the moduli obtained using these two different methods of measurement.
Microstructure and Mechanical Properties of Electroplated Cu Thin Films
Authors: Volinsky A.A. , Vella J. , Adhihetty I.S. , Sarihan V. , Mercado L. , Yeung B.H. , Gerberich W.W. 
Published: April 2011

ABSTRACTCopper films of different thicknesses of 0.2, 0.5, 1 and 2 microns were electroplated on top of the adhesion-promoting barrier layers on <100> single crystal silicon wafers. Controlled Cu grain growth was achieved by annealing films in vacuum.The Cu film microstructure was characterized using Atomic Force Microscopy and Focused Ion Beam Microscopy. Elastic modulus of 110 to 130 GPa and hardness of 1 to 1.6 GPa were measured using the continuous stiffness option (CSM) of the Nanoindenter XP. Thicker films appeared to be softer in terms of the lower modulus and hardness, exhibiting a classical Hall-Petch relationship between the yield stress and grain size. Lower elastic modulus of thicker films is due to the higher porosity and partially due to the surface roughness. Comparison between the mechanical properties of films on the substrates obtained by nanoindentation and tensile tests of the freestanding Cu films is made.
Adhesive Failure of a Thin Epoxy Film on an Aluminized Substrate
Authors: Moody N. R. , Bahr D. F. , Kent M. S. , Emerson J. A. , Reedy E. D. 
Published: April 2011

ABSTRACTIn this study we used nanoindentation to determine mechanical properties and combined nanoindentation with stressed overlayers to determine interfacial fracture energy of a 164 nm thick film of Epon 828/T403 on an aluminized glass substrate. The combination of nanoindentation and a tungsten overlayer was required to trigger delamination of the epoxy film from the aluminized substrate. Mechanics-based models for circular blister formation were then used to determine residual stresses and interfacial fracture energies. This approach showed that the tungsten overlayer had a compressive residual stress of 1.9 GPa which drove blister formation at a fracture energy of 1.9 J/m2 with a phase angle of loading equal to –62°.
Nanoindentation of Pressure Quenched Fullerenes and Zirconium Metal from a Diamond Anvil Cell
Authors: Catledge Shane A. , Spencer Philemon T. , Patterson Jeremy R. , Vohra Yogesh K. 
Published: April 2011

ABSTRACTThe sample size employed in high pressure diamond anvil cells is limited to a diameter of typically 25 to 150 microns. While this size is often sufficient for diagnostics using synchrotron x-ray diffraction and Raman scattering, ex-situ measurements of mechanical properties using conventional microhardness indentation techniques is not feasible. For some materials, the high pressure phase(s) can be quenched to ambient pressure allowing further characterization by other techniques. We make use of the very small probe volume allowed by nanoindentation to investigate the pressure-quenched structures of both C70 fullerene and zirconium. For the case of C70, we show that the amorphous phase established above 35 GPa can be quenched to ambient, and that it shows a largely elastic indentation loading behavior with a hardness of 30 GPa. We establish that this hard carbon phase contains a mixture of sp2- and sp3-bonded carbon and that it can be produced from C70 fullerene by application of pressure at room temperature. With regard to zirconium metal, we confirm the irreversible transformation from the ambient hexagonal-close-packed phase to the simple hexagonal Ω-phase (AlB2 structure) and document an 80% increase in hardness that may be attributed to the presence of covalent bonding based on sd2-hybridized orbitals forming graphite-like nets in the (0001) plane of the AlB2 structure.
Nanoindentation Evaluation of Brittle Films on Metals Natalia
Authors: Tymiak I. , Daugela Antanas , Page Trevor F. , Gerberich William W. 
Published: April 2011

ABSTRACTThe present study addresses two cases of brittle ceramic films on metals. With the assistance of AE as a supplementary technique, yield initiation phenomena have been evaluated for W single crystal surfaces under several nm thick native oxide film. An AE sensor coupled to an indenter tip allowed an increasing sensitivity to localized fracture and plasticity events in the vicinity of an indentation contact. A good correlation between AE signals and indentation induced plasticity and fracture has been accomplished for contacts below 100 μN. Second, mechanical behavior of porous nanocrystalline SiC films on Mo substrates was examined. An analysis was based on the P-δ2 approach. With this method, both loading and unloading parts of indentation curves obtained with sharp pyramidal indenters may be represented as P=Kδ2 where P, and δ denote indentation load and displacement respectively. The parameter K includes a material's hardness/modulus ratio and indenter geometry.
3D Mapping of Subsurface Cracks in Alumina Using FIB
Authors: Inkson B.J. , Wu H.Z. , Steer T. , Möbus G. 
Published: April 2011

ABSTRACTA new method has been developed to map cracks in 3D using focused ion beam (FIB) microscopy. Using the FIB, many parallel 2D slices are cut in the specimen. Imaging each 2D slice down several directions enables the 3D co-ordinates of features in the slice to be determined. Computer alignment and reconstruction of the 2D slices generates a 3D data set of the analysed zone. The 3D mapping method has been applied to the analysis of the cracks around an indentation site in a Al2O3-5vol.%SiC nanocomposite. This reveals the 3D location and morphology of radial and deep lateral cracks at the indent periphery, surface localised crack clusters, and a crack deficient zone close to the indent centre.
Physical Origin of a Size Effect in Nanoindentation
Authors: Bushby A.J. , Downes J.R. , Jayaweera N.B. , Kidd P. , Kelly A. , Dunstan D.J. 
Published: April 2011

ABSTRACTWe have reported results of nanoindentation using spherical indenters to observe the full indentation stress-strain curve. We observe the onset of plasticity in semiconductor strained-layer superlattices. These structures have alternating layers with strains of opposite sign. The yield pressure is reduced by the presence of the coherency strain. By varying the thicknesses and strains, we have been able to show that both sets of layers, compressive and tensile, reduce the yield pressure. This requires that a yield criterion must be satisfied over a volume, large enough to include layers of both sign. In these studies, we observe a large and reproducible size effect in the yield pressure. That is, with smaller radius indenters the mean pressure acting over the contact area at the deviation from purely elastic behaviour increases, by up to a factor of two for a 2μm radius indenter tip. Here we show how the requirement for meeting a yield criterion over a finite volume naturally leads to the size effect. Essentially, with smaller radius indenters, the peak stresses must be greater in order to satisfy the yield criterion over a finite volume. By integrating the strain energy over a suitable volume we show that there is a critical volume of ≍ 0.5μm radius over which yield is initiated for all indenter radii in the range 1-35μm. This is an important result for the understanding of nanoindentation and other systems in which stresses are highly inhomogeneous on a small scale.
Grain Boundary Modification During Neutron Irradiation at Intermediate Temperatures
Authors: Bruemmer S. M. , Edwards D. J. , Gertsman V. Y. , Simonen E. P. 
Published: April 2011

ABSTRACTGrain boundary compositions and near-boundary microstructures have been measured in complex Fe-Cr-Ni alloys after neutron irradiation at intermediate temperatures where nanometer-scale damage promotes structural integrity problems in nuclear reactor systems. Radiation-induced segregation (RIS) and dislocation loop microstructures have been determined as a function of irradiation dose up to 13 dpa and at temperatures near 280°C. The most significant effect on RIS was the grain boundary structure (low-energy special boundaries versus high-energy random boundaries) and composition (enrichment of Cr and Mo) before irradiation. Grain boundary character distribution did not change with irradiation and only high-energy boundaries exhibited significant radiation-induced changes. The initial grain boundary composition in mill-annealed stainless steels was difficult to remove during subsequent irradiation and retarded the development of Cr- and Mo-depleted regions.
Radiation-Induced Segregation in 316 and 304 Stainless Steels Irradiated at Low Dose Rate
Authors: Allen T. R. , Cole J. I. , Ohta J. , Dohi K. , Kusanagi H. , Kenik E. A. , Ridge Oak 
Published: April 2011

ABSTRACTAs part of the shutdown of the EBR-II reactor, structural materials were retrieved to analyze the effects of long-term irradiation on mechanical properties and microstructure. In this work, the effect of low dose rate irradiation (10−7 to 10−8 dpa/s) on grain boundary composition in 316 and 304 stainless steels was analyzed. Samples were taken from surveillance specimens and subassemblies irradiated in the reflector region of EBR-II at temperatures from 371-390°C to maximum doses of 30 dpa. The effects of dose, dose rate, and bulk composition on radiation- induced segregation are analyzed. In 316 stainless steel, changes in grain boundary chromium and nickel concentrations occur faster than changes in iron and molybdenum concentrations. In 304 stainless steel, decreasing the dose rate increases the amount of grain boundary segregation. For a dose of 20 dpa, chromium depletion and nickel enrichment are greater in 304 stainless steel than in 316 stainless steel, the difference most likely due to dose rate. In both 304 and 316 stainless steels, the presence of a grain boundary precipitate significantly changes the composition of the adjacent grain boundary.
Concurrent Annealing Of Vacancy-Type And Interstitial-Type Damage In Neutron Irradiated Stainless Steel
Authors: Simonen E. P. , Edwards D. J. , Bruemmer S. M. 
Published: April 2011

ABSTRACTAnalysis of the effect of annealing on change in void and loop size distributions provided insights that complement microstructural characterization using transmission electron microscopy (TEM). The predictions of concurrent vacancy-type and interstitial-type damage annealing are applied to measurements in neutron-irradiated austenitic stainless steels. Irradiation at 330°C produces void and loop microstructures for which the measured annealing response is in accord with predictions. Irradiation at 275° produces only Frank loop microstructure for which the annealing response cannot be predicted from measured microstructures. The model predictions are based on an assumed vacancy source not detected using TEM. The measured loop microstructure is typically reported to be interstitial in character but this analysis suggests that a significant component of the loop population is vacancy-type damage based on defect inventory and kinetic arguments.