bluuebunny/crossref_metadata_2025_split huggingface dataset:
Powder processing of ductile materials for high pressure studies: application to intermetallic alloys
Authors: Otto J. W. , Frommeyer G. , Vassiliou J. K. 
Published: April 2011

ABSTRACTDuctile materials are difficult to powderize for use in high pressure work. The potential of different techniques (gas-atomization, mechanical alloying, ball milling and subsequent annealing) for preparing suitable powders of some aluminides is investigated. Compression of Ti46Al54and NiAl prepared by these methods yields equation of state parameters in good agreement with determinations by other methods.
Effects of Pressure on Plastic Deformation of Polycrystalline Solids: Some Geological Applications
Authors: Karato S. 
Published: April 2011

ABSTRACTExperimental studies on the effects of pressure on plastic properties are reviewed with an emphasis on those on geological materials. High pressures may affect plastic properties through two different ways: (i) through the effects of pressure on plastic deformation of a material with a given crystal structure and (ii) through the effects of pressure-induced phase transformations on plastic deformation. It is emphasized that the manner in which pressure affects plastic properties of solids depends on the microscopic mechanisms of plastic deformation and therefore it is essential to identify the mechanisms of deformation involved in a particular experimental condition. Three mechanisms are considered: (i) the Peierls mechanism, (ii) dislocation creep (power-law creep) and (iii) diffusion creep (or superplasticity). Creep strength of materials changes with pressure through the change in shear modulus and in the activation enthalpy for the Peierls mechanism. Structural phase transformations can dramatically change the creep strength determined by the Peierls mechanism. Changes can be either positive (increase in strength in a high pressure phase) or negative (decrease in strength in a high pressure phase). Creep strength controlled by dislocation creep usually increases exponentially with pressure through the increase in the activation enthalpy with pressure. Phase transformations can change the creep strength either positively or negatively for this mechanism depending on the manner in which dislocation mobility changes with crystal structure. Creep strength corresponding to diffusion creep changes with pressure in a similar fashion as dislocation creep.High pressures in the deep interior of Earth and other terrestrial planets could lead to a significant increase in viscosity with depth, resulting in high temperatures due to the feedback between viscosity and temperature. Also phase transformations in constituent minerals that occur in certain depth ranges can cause dramatic changes in plastic properties. Both of them are likely to have important influence on the style of convection in the mantle of terrestrial planets and thus affect their geological history and tectonic activities.
Surface-particle interactions in the chemical mechanical polishing process
Authors: Adler J. J. , Rabinovich Y. I. , Singh R. K. , Moudgil B. M. 
Published: April 2011

ABSTRACTChemical mechanical polishing (CMP) is a critical step in the fabrication of integrated circuits. Each layer of deposited material must be planarized before the next layer of circuitry can be formed. In CMP, a chemically active solution is used to modify the substrate so that a particulate abrasive may polish more efficiently. Modification of the surface often requires high oxidizer concentrations or pH extremes. Under these circumstances the stability of the polishing slurry and prevention of particulate attachment to the substrate is a difficult problem. In this study, atomic force microscopy (AFM) has been used to directly measure the forces between surfaces that simulate those in CMP. Initial investigation has focused on modeling the polishing of tungsten interconnect material by alumina slurries at acidic pH and evaluating the role surfactants can play in the stabilization of the polishing slurry and CMP processes.
Dispersion of Metal Oxide Nanoparticles in Conjugated Polymers: Investigation of the Tio2/PPV Nanocomposite
Authors: Baraton M.-I. , Merhari L. , Wang J. , Gonsalves K. E. 
Published: April 2011

ABSTRACTIt is well established that the dispersion of nanosized metal particles in a polymer matrix can induce non linear optical properties, yet very little is known about the effect of semiconducting transition metal oxide nanoparticles on both electrical and luminescence properties of conjugated polymers. In this paper, we report the synthesis of a nanostructured TiO2/poly(pphenylenevinylene) system and show by diffuse reflectance infrared Fourier transform spectrometry (DRIFTS) that a stable conjugated nanocomposite is obtained. Investigation of the photoluminescence (PL) properties reveals both a broadening and a blue shift of the emission spectra. Adsorption of oxygen is found to be stronger on the nanocomposite than on PPV and to reversibly quench the PL emission, thus suggesting enhanced gas sensing properties. A tentative mechanism explaining the role of n-TiO2 is briefly discussed.
Radiation Damage Effects in Ferroelectric Litao3 Single Crystals
Authors: Wetteland C. J. , Sickafus K. E. , Gopalan V. , Mitchell J. N. , Hartmann T. , Nastasi M. , Maggiore C. J. , Tesmer J. R. , Mitchell T. E. 
Published: April 2011

ABSTRACTZ-cut lithium tantalate (LiTaO3) ferroelectric single crystals were irradiated with 200 keV Art++ ions. LiTaO3 possesses a structure that is a derivative of the corundum (A12O3) crystal structure. A systematic study of the radiation damage accumulation rate as a function of ion dose was performed using ion-beam channeling experiments. An ion fluence of 2.5•1018 Ar2+ ions/m2 was sufficient to amorphize the irradiated volume of a LiTaO3 crystal at an irradiation temperature of ∼120K. This represents a rather exceptional susceptibility to ion-induced amorphization, which may be related to a highly disparate rate of knock-on of constituent lattice ions, due to the large mass difference between the Li and Ta cations. We also observed that the c− end of the ferroelectric polarization exhibits slightly higher ion dechanneling along with an apparent greater susceptibility to radiation damage, as compared to the c+ end of the polarization.
Giant Magnetoresistance in Iron and Cobalt Implanted Silver Thin Films
Authors: De Jesus C. M. , Marques J. G. , Soares J. C. , Redondo L. M. , Silva M. F. Da , Pereira De Azevedo M. M. , Sousa J. B. 
Published: April 2011

ABSTRACTThe magnetoresistive behavior of granular thin films prepared by Fe and Co implantation in Ag thin films is reported. Ag thin films (∼2000Å) were implanted with Fe or Co at fluences up to 8×1016 at./cm2. The magnetoresistive response obtained after implantation was found to increase with the implanted fluence. A further increase by a factor of 3–4 can be achieved annealing the films in a conventional furnace at 620 K under vacuum. The best value of the magnetoresistance obtained so far is 9% at 10 K for a film implanted with Co at a fluence of 8×1016 at./cm2.
Defect Evolution in Ion Implanted Si: from Point to Extended Defects
Authors: Libertino Sebania , Benton Janet L. , Coffa Salvatore , Eaglesham Dave J. 
Published: April 2011

ABSTRACTSeveral recent experiments assessing the role of impurities (C, O), dopants (P, B) and clustering on defect evolution in ion implanted Si are reviewed. Deep level transient spectroscopy measurements were used to analyze the defect structure in a wide range of ion implantation fluences (1×108–5×1013 cm−2) and annealing temperatures (100–800 °C). By using substrates with a different impurity content and comparing ion implanted and electron irradiated Si samples, many interesting features of defect evolution in Si have been elucidated. It is found that only a small percentage, 4–16 % depending on ion mass, of the Frenkel pairs generated by the beam escape direct recombination and is stored into an equal number of room temperature stable vacancy- (V-) and interstitial-type (I-) defect complexes. Identical defect structures and annealing behavior have been measured in ion implanted (1.2 MeV Si, 1×108–1×1010/cm2) and electron irradiated (9.2 MeV to fluences between 1 and 3×1015/cm2) samples in spite of the fact that denser collision cascades are produced by the ions. The O and C content of the substrate plays a major role in determining the point defect migration, the room temperature stable defect structures and their annealing behavior. Annealing at temperatures up to 300 °C produces a concomitant reduction of the I- and V-type defect complexes concentration, demonstrating that defect annihilation occurs preferentially in the bulk. At temperatures above 300 °C, when all V-type complexes have been annealed out, ion implanted samples present a residual I-type damage, storing 2–3 I per implanted ion. This unbalance is not observed in electron irradiated samples and it is a direct consequence of the extra implanted ion. The simple point defect structures produced at low ion fluence (1×108–1×1011 /cm2) anneal at ∼ 550 °C. At higher fluences (∼ 1012–1013/cm2) and for annealing temperatures above 500 °C the deep level spectrum is dominated by two signatures at Ev+0.33 eV and at Ev+0.52 eV that we have associated to Si interstitial clusters. Impurities (C, O and B) play a role in determining nucleation kinetics of these defects, but they are not their main constituents. The dissolution temperature of these clusters indicates that they might store the interstitials that drive transient enhanced diffusion phenomena occurring in the absence of extended defects. Finally, at higher implantation fluence, a signature of extended defects is observed and associated to the presence of {311} defects detected by transmission electron microscopy analyses.
Silver Nanocluster Formation In Implanted Silica
Authors: Mariotto G. , Freire F. L 
Published: April 2011

ABSTRACTSamples of fused silica were implanted at room temperature with 300 keV-Ag+ for doses ranging from 0.8×1016 to 14×1016 ions/cm2. A multi-technique approach including Rutherford backscattering spectrometry (RBS), x-ray diffraction (XRD), optical absorption and Raman scattering spectroscopies has been used to characterize silver precipitate. The Ag-depth profiles of samples implanted with doses higher than 6×1016 Ag+/cm2 show a bi-modal distribution, with the appearance of a secondary maximum near the surface. XRD spectra indicated the formation of silver nanocrystals of ∼10 nm in size within the heavily implanted samples. Optical absorption has been used to monitor the effects of ion doses on the optical properties of the metal clusters in the UV-Vis region. A single broad absorption band, due to surface plasmon resonance, is peaked at about 400 nm for low implantation doses. For doses higher than 4.3×1016 Ag+/cm2, a second broad band originates at higher wavelengths, peaking at 625 nm for the highest dose. The evolution of optical spectra is tentatively discussed in terms of the formation of silver particle aggregates with no longer spherical shape. An estimate of the mean size of silver nanoclusters of about 5.5 nm is obtained from low-frequency Raman scattering due to acoustic vibrations localized at the cluster surface. The discrepancies in the metal particle size obtained from XRD and Raman scattering measurements are discussed with respect to optical absorption data.
Study of the Effects of MeV Ag, Cu, Au and Sn Implantation on the Optical Properties of LiNbO3
Authors: Williams E. K. , Ila D. , Sarkisov S. , Curley M. , Poker D. B. , Hensley D. K. , Borel C. 
Published: April 2011

ABSTRACTWe present the results of characterization of linear absorption and nonlinear refractive index of Au, Ag, Cu and Sn ion implantation into LiNbO3. Silver was implanted at 1.5 MeV to fluences of 2 to 17 × 1016/cm2 at room temperature. Gold and copper were implanted to fluences of 5 to 20 × 1016/cm2 at an energy of 2.0 MeV. Tin was implanted to a fluence of 1.6 × 1017/cm2 at 160 kV. After heat treatment at 1000°C a strong optical absorption peak for the Au implanted samples appeared at ∼620 nm. The absorption peaks of the Ag implanted samples shifted from ∼450 nm before heat treatment to 550 nm after 500°C for lh. Heat treatment at 800°C returned the Ag implanted crystals to a clear state. Cu nanocluster absorption peaks disappears at 500°C. No Sn clusters were observed by optical absorption or XRD. The size of the Ag and Au clusters as a function of heat treatment were determined from the absorption peaks. The Ag clusters did not appreciably change in size with heat treatment. The Au clusters increased from 3 to 9 nm in diameter upon heat treatment at 1000°C. TEM analysis performed on a Au implanted crystal indicated the formation of Au nanocrystals with facets normal to the c-axis. Measurements of the nonlinear refractive indices made using the Z-scan method showed that Ag implantation changed the sign of the nonlinear index of LiNbO3 from negative to positive.
In-situ observation of atomic processes in Xe nanocrystals embedded in al
Authors: Mitsuishi K. , Song M. , Furuya K. , Birtcher R. C. , Allen C. W. , Donnelly S. E. 
Published: April 2011

ABSTRACTSelf-organization processes in Xe nanocrystals embedded in Al are observed with in-situ high-resolution electron microscopy. Under electron irradiation, stacking fault type defects are produced in Xe nanocrystals. The defects recover in a layer by layer manner. Detailed analysis of the video reveals that the displacement of Xe atoms in the stacking fault was rather small for the Xe atoms at boundary between Xe and Al, suggesting the possibility of the stacking fault in Xe precipitate originating inside of precipitate, not at the Al/Xe interface.
Study of the effects of MeV Ions on PS and PES
Authors: Evelyn A. L. , Ila D. , Zimmerman R. L. , Bhat K. , Poker D. B. , Hensley D. K. , Just N. 
Published: April 2011

ABSTRACTThe electronic and nuclear stopping effects produced by MeV ion bombardment in polyethylene (PE) and polyvinylidene chloride (PVDC) have been previously studied and reported. We have subsequently selected two other insulators: polystyrene (PS) and polyethersulfone (PES) which contains sulfur as a crosslinking agent, and irradiated them with MeV alpha particles. The electronic and nuclear effects of the incident ions were separated by stacking thin films of the polymers. A layered system was selected such that the first layers experienced most of the effects of the electronic energy deposited and the last layers received most of the effects of the nuclear stopping. The changes in the chemical structure were measured by residual gas analysis (RGA), Raman microprobe analysis, RBS and FTIR. The post-irradiation characterization resolved the effects of the stopping powers on the PS and PES and the results were compared with those from PE and PVDC.
Molecular Dynamics Simulation of Fullerene Cluster Ion Impact
Authors: Aoki Takaaki , Seki Toshio , Tanomura Masahiro , Matsuo Jiro , Insepov Zinetulla , Yamada Isao 
Published: April 2011

ABSTRACTIn order to interpret the projection range and to reveal the mechanism of damage formation by cluster ion impact, molecular dynamics simulations of a fullerene carbon cluster (C60) impacting on diamond (001) surfaces were performed. When the kinetic energy of C60 is as low as 200eV/atom, C60 implants into the substrate deeper than a monomer ion with the same energy per atom because of the clearing-way effect. The kinetic energy of the cluster disperses isotropically because of the multiple-collision effect, and then a large hemispherical damage region is formed. When the energy of the cluster is as high as 2keV/atom, the cluster dissociates in the substrate, and then cascade damage is formed like in a case of a monomer ion impact. The projection range of incident atoms becomes similar to that of the monomer with the same energy per atom. However, the number of displacements of C60 is larger than the summation of 60 monomer carbons. The displacement yield of fullerene is 4 to 7 times higher than that of monomer carbon. This result agrees with the measurement of the displacements made on sapphire substrates with C60 and C2 irradiation.
High Quality Oxide Film Formation by 02 Cluster Ion Assisted Deposition Technique
Authors: Matsuo J. , Qin W. , Akizuki M. , Yodoshi T. , Yamada I. 
Published: April 2011

ABSTRACTA new oxide film formation technique using gas-cluster ion beams has been developed. 02 cluster ions were used to irradiate during the evaporation of metal atoms, and PbOx and In203 films were grown. At the acceleration voltages above 5 kV, polycrystalline PbOx films preferentially oriented to (111) were obtained. A significant smoothing effect was observed with an acceleration voltage as low as 1 kV. An average surface roughness of 0.9 nm was obtained at 7 kV. Oxygen cluster ion beams are also utilized to grow In203 films, which are widely used as conductive-transparent films in flat panel display. In203 was deposited on glass or silicon substrates with simultaneous irradiation with an oxygen cluster ion beam. Highly transparent (80%) and low resistivity (<4×10−4 Ωcm) films were obtained with 7keV oxygen cluster ion beams. Kinetic energy of above 3keV is necessary to obtain low resistivity films. These results clearly indicate that the kinetic energy of the cluster is effectively used to enhance oxidation on the surface without radiation damage, in spite of the high acceleration voltages.
Discovery of Long Range Order in Thin (2-20 NM) SiO2 Films by Ion Beam Analysis
Authors: Herbots N. , Atluri V. , Hurst Q. B. , Shaw J. M. , Banerjee S. , Bradley J. D. , Culbertson R. J. , Smith D. J. 
Published: April 2011

AbstractSiO2 films, 2-20 nm thick, were grown on passivated, ordered Si(100) to correlate electrical properties and oxidation rates with processing for ultra-thin gate oxides. Ordered Si(l 00) (1 × 1) stable in ambient air was obtained at room temperature by wet chemical cleaning. The thickest oxides were grown by Rapid Thermal Oxidation at 850°C, the thinnest at room temperature. O was detected by Ion Beam Analysis (IBA) using a combination of ion channeling with the 3.05 MeV 16O(α,α)16O nuclear resonance. It then becomes possible to measure order in thin SiO2 by comparing the total amount of O from rotating random spectra to disordered O detected by ion channeling, and detect the alignment of O with the atoms in Si(100)
Formation Energy of Interstitial Si in Au-Doped Si
Authors: Suezawa Masashi 
Published: April 2011

AbstractIn this report, we proposed that complexes responsible for optical absorption lines in Si grown in a hydrogen (H) atmsophere were composed of interstitial Si and H atoms and then determined the formation energy of interstitial Si in Au-doped Si from the measurements of optical absorption due to H bound to interstitial Si. In the first experiment, specimens were grown in a hydrogen atmosphere. In the second experiment, Si crystals were doped with Au by a vapor method; namely, specimens were sealed in quartz capsules together with a piece of Au wire and then annealed at high temperature followed by quenching in water. Then the specimens were doped with H by annealing them in hydrogen atmosphere of 1 atm. followed by quenching. We measured optical absorption of those specimens. From the effect of impurity on the optical absorption spectra of Si grown in a hydrogen atmosphere, we concluded that those optical absorption lines, including 2223 cm−1line, were due to complexes of interstitial Si and H. From the temperature dependence of the intensity of 2223 cm−1line, the formation energy of interstitial Si in Au-doped Si was determined to be about 2.1 eV
Damage in High Energy Light Ions Irradiated Silicon Carbide
Authors: Leveque P. , Godey S. , Renault P.O. , Ntsoenzok E. , Barbot J.F. 
Published: April 2011

AbstractCommercial n-type 4H-SiC wafers were implanted with doses of MeV alpha particles, high enough to cause majority carrier modification. Analysis of infrared reflectivity spectra shows that the implanted crystals can be divided into three layers: a surface layer of about 30 nm followed by a compensation layer where the energy transfer of the incident particles is low and an overdoping layer in the region of maximum defect production, i.e. near the theoretical mean range of ions Rp
Peculiarities of Zn Diffusion from Polymer Spin-on Films in AlGaAs
Authors: Kamanin A.V. , Mintairov A.M. , Shmidt N.M. 
Published: April 2011

AbstractZn diffusion into AlxGa1−xAs from polymer spin-on films has been investigated. An increase in Zn diffusivity has been observed with increase in the content of Al in A1GaAs compounds. The effect has been related to more coefficient of self-diffusion for Al than for Ga. The availability of the near-surface layer enriched with Al in epitaxial AlGaAs wafers has been found to result in poor reproducible diffusion characteristics.
Plasma Chemistry Study of Plasma Ion Implantation Doping for Cmos Devices
Authors: Qin Shu , Zhou Yuanzhong , Chan Chung 
Published: April 2011

AbstractPlasma ion implantation (PII) doping processes utilizing PH3/He and B2H6/He plasmas to fabricate CMOS devices are presented. The impact of plasma chemistry of PH on device structure and characteristics are studied. By using an optimized process condition, low contamination levels and good device characteristics have been achieved.
Edge Effects of Nitride Film Patterning on Dislocation Generation in Local Oxidation of Silicon
Authors: Peidous I. V. , Sundaresan R. , Quek E. , Lau C. K. 
Published: April 2011

AbstractExtensive monitoring of device characteristics in the manufacturing of ULSI with advanced LOCOS isolation revealed the strong dependence of device leakage currents on the process of patterning of silicon nitride films applied as a hard mask for local oxidation of silicon wafers. At the same time, the level of the leakage currents strongly correlated to stress-induced dislocation density in the device structures. Formation of microtrenches on the wafer surface at the nitride film edges was identified to have a major impact on the leakage currents. Surprisingly, structures having nitride film edge profiles with feet were consistently dislocation-free after the local oxidation. This showed that nitride etching process created surface damage that provided effective sites for crystal defect nucleation in silicon at the film edges. Computer simulations demonstrated that the feet at nitride edges substantially suppress stress growth during local oxidation.
The Incorporation and Complex Formation of Ag Acceptors in CdTe
Authors: Wolf H. , Filz T. , Hamann J. , Ostheimer V. , Lany S. , Wichert Th. , Deicher M. , Burchard A. 
Published: April 2011

AbstractUsing the radioactive isotope 111Ag, the incorporation of Ag into CdTe is investigated by photoluminescence spectroscopy (PL) and the perturbed yy-angular correlation technique (PAC). PL is used to demonstrate the incorporation as a substitutional acceptor (AgCd) by monitoring the intensity of the donor-acceptor transition, corresponding to an acceptor level of EV + 108 meV, which decreases just with the half life of the radioactive decay of the 111Ag isotope. Since the isotope 111Ag also serves as a probe atom for PAC experiments, it is possible to confirm the incorporation of Ag atoms on lattice sites with cubic symmetry. Additionally, in CdTe a defect complex is detected, which is assigned to a AgCd-VTe pair. A second defect complex is observed in CdTe doped with In, which is assigned to an InCd-AgCd pair. By PAC experiments with the probe 111In that are performed in Ag doped CdTe, the formation of the InCd-AgCd pair is confirmed besides the well known formation of the InCd-VCd pair. The migration energy of the cation vacancy is estimated on the basis of an isothermal annealing sequence.