bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface enhanced Raman Active Nanoparticles in Plasma Treated Silver surfaces
Authors: Compagnini G. , Pelligra B. , Pignataro B. 
Published: April 2011

ABSTRACTA plasma oxidation-reduction process has been found to be suitable to produce silver surfaces showing Surface Enhanced Raman (SER) activity. SER spectra of monodisperse polystyrene films and of other smaller molecules like alkanethiole, have been obtained in order to study the correlation between enhancement and nanomorphology as probed by Atomic Force Microscopy. It was found that the enhancement is strongly correlated with a coalescence of the initially present silver grains (10–50 nm in size). This coalescence leads to the formation of 100–300 nm silver hills in which each silver grain is still clearly distinguishable. The increase of the effective surface area due to the particle coalescence has been correlated to the SERS enhancement in straightforward fashion while self assembled alkanethiole monolayers have been used as spacer for electromagnetic SERS enhancement of polystyrene.
Preparation and characterization of concentric-tubular composite microstructures using the template synthesis method
Authors: Cepak Veronica M. , Martin Charles R. 
Published: April 2011

ABSTRACTThe template method has been used to prepare concentric-tubular composite microstructures. These composite structures consist of an outer tubule composed of one material encapsulating concentric inner tubules composed of other materials. Tubular composites of this type consisting of metals, semiconductors, polymers, and Li-ion intercalation materials have been prepared. The chemical strategies used to prepared these composite structures include electroless plating of Au, electropolymerization of electronically conductive and insulating polymers, electrodeposition of metals and semiconductors, and sol-gel synthesis.
Preparation and characterization of SiO2/Au nanocomposites by R.F. Sputtering
Authors: Terauchi Shinya , Umehara Hiroyuki , Koshizaki Naoto , Sasaki Takeshi 
Published: April 2011

ABSTRACTWe fabricated SiO2/Au nanocomposites using alternate sputtering method. The size of the Au particles seem was unchanged by the SiO2 sputtering and well controllable by the sputtering parameters. The nanoparticles in SiO2 were observed by TEM and the nanocomposites were characterized using XPS technique. TEM observation revealed the size of Au nanoparticles to be 2–15 nm. We observed a chemical shift of the Au4f peak in the XPS study. We demonstrate the efficiency of the technique for controlling the size and quantity of nanoparticles dispersed in nanocomposites.
Modeling of strain distribution in non-hydrostatically pressed nanocrystalline sic; in-situ x-ray diffraction study
Authors: Pielaszek R. , Stel'Makh S. , Aloshina M. , Gierlotka S. , Palosz B. 
Published: April 2011

ABSTRACTGrain size and strain distribution functions of polycrystals of SiC with nanosize grains were examined based on X-ray diffraction data and ab initio calculations of scattered intensity from Debye functions. A tentative model of distribution of strain induced under high isostatic pressure in nanoparticles with different grain size is presented. Nanocrystalline SiC powders with grains down to 80Å in diameter were examined. In situ high pressure diffraction experiments were performed in cubic anvil cell MAX80 (up to 6 GPa) and in Diamond Anvil Cell (DAC) (up to 45 GPa) at HASYLAB, Hamburg, Germany. Shape of the Bragg lines was analysed with the use of two methods: (i) calculation of theoretical diffraction patterns based on modeling of one-dimensional disordering and ab initio calculation of scattered intensity starting from Debye functions and, (ii) approximation of the experimental shape of Bragg reflections by a combination of two functions: Gaussian (G) and Lorentzian (L).
Synthesis and Characterization of Antimony-Doped Tin Oxide Nanophase materials for Electrochromic Applications
Authors: Liu J. , Coleman J. P. , Madhukar P. 
Published: April 2011

ABSTRACTAntimony-doped tin oxide (ATO) nanophase materials containing up to 43 mole% antimony have been synthesized by a wet-chemistry method. These ATO materials exhibit enhanced electrochromic properties for display devices. The performance of the display devices is related to the nanostructure of the synthesized ATO materials. The average sizes of the ATO nanocrystallites depend on dopant level, annealing conditions, and synthesis processes. Antimony inhibits the growth of tin dioxide nanocrystallites during annealing at moderate temperatures. At higher annealing temperatures, however, antimony segregates to form separate oxide phases and ATO nanocrystallites grow significantly. A systematic study of the structural evolution of the synthesized ATO materials is presented and the relationship between the nanostructure of the ATO materials and the enhanced performance of the corresponding electrochromic devices is discussed.
Mechanism of Enhanced Diffusion of Aluminum in 6H-SiC in the Process of High-Temperature Ion Implantation
Authors: Usov Igor O. , Suvorova A. A. , Sokolov V. V. , Kudryavtsev Y. A. , Suvorov A. V. 
Published: April 2011

ABSTRACTThe diffusion of Al in 6H-SiC during high-temperature ion implantation was studied using secondary ion mass spectrometry. A 6H-SiC wafer was implanted with 50 keV Al ions to a dose of 1.4E16 cm−2 in the high temperature range 1300°–1800TC and at room temperature. There are two diffusion regions that can be identified in the Al profiles. At high Al concentrations the gettering related peak and profile broadening are observed. At low Al concentrations, the profiles have a sharp kink and deep penetrating diffusion tails. In the first region, the diffusion coefficient is temperature independent, while in the second it exponentially increases as a function of temperature. The Al redistribution can be explained with the substitutional-interstitial diffusion mechanism.
A Model for Irradiation-Induced Amorphization
Authors: Wang S. X. , Wang L. M. , Ewing R. C. 
Published: April 2011

ABSTRACTA model based on cascade melting and recrystallization is derived to describe ion irradiation-induced amorphization. The accumulation of amorphous volume fraction during irradiation is represented in a single equation. Depending on the extent of recrystallization of a subcascade, the amorphous volume accumulation can be described by a set of curves that change from exponential to sigmoidal functions. The parameters (including temperature, cascade size, crystallization rate, glass transition temperature, dose rate) that affect the extent of recrystallization are included in the model. The model also describes the temperature dependence of critical dose for amorphization.
Magnetostriction Related Effects in Pulsed Laser Irradiation of Amorphous Magnets
Authors: Sorescu Monica , Schafer S. A. 
Published: April 2011

ABSTRACTSamples of Fe66Co18B15Si1, Fe40Ni38Mo4B18 and Fe72.6Cr22Al4.8Si0.3Y0.3 metallic glasses were irradiated with a pulsed alexandrite laser (λ=750 nm, τ=60 μs) using different laser fluences. Irradiation-induced structural and property modifications were characterized using Mössbauer spectroscopy. Complementary information was obtained from hysteresis loop measurements and scanning electron microscopy (SEM). The experimental data obtained demonstrate the key role played by the magnetostriction constant in explaining the mechanism of irradiation-induced phase transformations in amorphous magnets.
Electronic Excitation Effects on Defect Production and Radiation Annealing in Fe Irradiated at ∼80K with Energetic Particles
Authors: Chimi Y. , Iwase A. , Ishikawa N. 
Published: April 2011

ABSTRACTDefect accumulation behavior in Fe irradiated with high energy (∼100MeV) ions, low energy (∼1MeV) ions and 2MeV electrons was studied by measuring the electrical resistivity change of the specimen at ∼80K as a function of particle fluence. From the experimental results, the defect production cross-section, the defect annihilation cross-section and the damage efficiency (the ratio of the experimental defect production cross-section to the calculated one) were derived for each irradiation. By comparing the results for high energy ion-irradiations with those for low energy ion- and electron-irradiations, the dependence of defect production and radiation annealing on the electronic excitation is discussed.
Metastable Materials Formation by ion Beam Assisted Deposition: Application to M Clusters in Ceramic Matrices
Authors: Carosella C. A. , Hubler G. K. , Cotell C. M. , Schiestel S. 
Published: April 2011

ABSTRACTThe collision cascade, the fundamental event in ion-solid interactions, is responsible for the beneficial effects on thin films deposited by low energy ion beam assisted deposition (IBAD) or by energetic ion assisted deposition processes in general. However, the fundamental implications of the marriage of collision cascades and film growth processes have yet to be fully realized. The first half of this paper reviews the effects of ion bombardment on film growth and reaches some new conclusions. We propose that IBAD represents a different ion-solid interaction in a fundamental sense, and that as such, it should lead to new microstructures unattainable by other materials synthesis methods.The second part of this paper discusses the deposition of metal nanoclusters in a dielectric matrix by means of beam assisted phase separation (BAPS), a term coined here to describe deposition of phase-separated multicomponent materials. Examples discussed are gold nanoparticles in both niobium oxide and silica matrices.
Effect of Ion Energy on Structural and Chemical Properties of Tin Oxide Film in Reactive Ion-Assisted Deposition (R-Iad)
Authors: Cho Jun-Sik , Choi Won-Kook , Yoon Ki Hyun , Cho J. , Yoon Young-Soo , Jung Hyung-Jin , Koh Seok-Keun 
Published: April 2011

ABSTRACTTin oxide films were deposited on in-situ heated Si (100)substrates using reactive ionassisted deposition and the effect of average impinging energy of oxygen ions on the crystalline structure and the stoichiometry of deposited films were examined. The transformation from SnO phase to SnO2 phase of the films was dependent on the change of the average impinging energy of oxygen ion (Ea), and the relative arrival ratio of oxygen to tin. Perfect oxidation of SnO2 was performed at Ea = 100, 125 eV/atom at as low as 400 Å substrate temperature. The composition (No/Nsn) of films increased from 1.21 to 1.89, and was closely related to the average impinging energy of oxygen ion. The surface morphology of the films was also investigated by scanning electron microscopy.
Improving the Thermal Stability of Photoresist Films by Ion Beam Irradiation
Authors: Zawislak F. C. , Garcia Irene T. S. , Samios D. , Baptista D. L. , Fichtner P. F. P. , Alves E. , Silva Maria F. Da , Soares J. C. 
Published: April 2011

ABSTRACTThe thermal stability of ion irradiated 1.7 μm thick AZ-1350J photoresist films was investigated using the RBS and ERDA techniques to measure the composition of the irradiated and annealed films. The films have been irradiated with He, N and Ar ions at energies from 380 to 760 keV and fluences between 2 × 1015 and 1016 ions cm−2. A considerable increase in the thermal stability of the He irradiated film is observed from ≈200°C – when the non-irradiated film starts to decompose – to 400°C after the irradiation. The FTIR spectroscopy and the SEM observations were used to study the chemical structural changes and the surface morphology of the irradiated samples. The results are discussed in terms of the energy density deposited by the ions, the large loss of H during irradiation, and the resulting increase in cross-linking density.
Hydrogen Diffusion in Boron Doped Diamond: Evidence of Hydrogen-Boron Interactions
Authors: Chevallier J. , Theys B. , Grattepain C. , Deneuville A. , Gheeraert E. 
Published: April 2011

AbstractDeuterium diffusion has been investigated in boron doped diamond as a function of the diffusion temperature and the boron concentration. The results show that, up to 480°C, hydrogen diffusion is limited by the boron concentration with a diffusion activation energy of 0.35 eV for [B] = 5×1019 cm−3. This first experimental evidence of deuterium-boron interactions in diamond is interpreted as the result of hydrogen ionization and diffusion of fairly mobile protons which form pairs with negatively charged boron acceptors
First-Principles Study of N Impurities in SiC Polytypes
Authors: Windl W. , Demkov A. A. 
Published: April 2011

AbstractWe investigate theoretically the energetics of nitrogen impurities in β-SiC, their geometrical relaxation, and electronic properties. We find that density-functional theory is able to calculate donor-ionization energies accurately once large enough simulation cells are used. For neutral interstitial defects, we find that configurations where N is three-fold coordinated have very low formation energies and high binding energies with the involved native defects. At the same time, such configurations introduce deep levels into the gap which may result in a non-activation of the donor
Iron and Nickel Solubilities in Heavily Doped Silicon and their Energy Levels in the Silicon Band Gap at Elevated Temperatures
Authors: McHugo S.A. , McDonald R.J. , Smith A.R. , Hurley D.L. , Istratov A.A. , Hieslmair H. , Weber E.R. 
Published: April 2011

AbstractWe have directly measured the solubility of iron and nickel in high and low boron-doped silicon using Instrumental Neutron Activation Analysis. Boron doping levels were 1.5×1019 and 6.5× 1014 atoms/cm3. Iron and nickel impurity concentrations were measured after extended indiffusions at 800, 900, 1000 and 1100°C for iron and 600, 700 and 800°C for nickel. We have measured a significant enhancement of Fe and Ni concentrations in high boron-doped silicon as compared to low boron-doped silicon. Based on these measurements, we show the iron donor energy level shifts towards the valence band with increased temperature, e.g. at 900°C the donor level is 0.24eV above the valence band as opposed to 0.39eV at room temperature. These results demonstrate that the impurity energy level shift with temperature must be accounted for in any prediction of segregation gettering of metal impurities into heavily doped substrates and heavily implanted doping layers. Additionally, our results suggest that either Ni solubility is greatly enhanced and/or the Ni diffusivity is greatly decreased with high boron doping of silicon.
Vacancy-Type Defects in Electron and Proton Irradiated II-VI Compounds
Authors: Brunner S. , Puff W. , Mascher P. , Balogh A.G. 
Published: April 2011

AbstractIn this contribution we present a study aimed at comparing results of positron-lifetime and Doppler-broadening measurements on the wide-band-gap compound semiconductors ZnS, ZnSe, and ZnTe. To investigate the basic properties of intrinsic and radiation induced defects the samples were irradiated either with 3 MeV protons or 1 MeV electrons. The isochronal annealing was performed in an Ar atmosphere. It was found that electron and proton irradiation cause different changes in the positron annihilation characteristics. Several annealing stages were observed, related to the annealing of variously sized vacancy complexes.
Characterization of the Structure and Polarity of Twin Boundaries in GaP
Authors: Cohent Dov , Medlin D.L. , Barry Carter C. 
Published: April 2011

AbstractThe structure of planar defects in GaP films grown by MBE on Si (110) was investigated by transmission electron microscopy. Growth of GaP films on the (110) surface produced numerous microtwins which formed both first and second order twin boundaries. Using high-resolution transmission electron microscopy, the atomic structure of Σ=3 and Σ=9 twin boundaries were studied. Both the Σ=3 and Σ=9 interfaces were observed to facet along specific crystallographic planes. Geometric models of the Σ=9 {221} twin boundary accounting for different polar bonding configurations were proposed and compared with experimental observations.
Impurity Segregation in Al Doped GaSb Studied by Cathodoluminescence Microscopy
Authors: Hidalgo P. , Mendez B. , Piqueras J. , Dutta P.S. 
Published: April 2011

AbstractCathodoluminescence (CL) in the scanning electron microscope (SEM) has been used to investigate the effect of doping with an isoelectronic dopant, aluminum, on the native acceptors and on the general structure of extended defects of gallium antimonide single crystals. While there is no significant change in the native defect content, decoration of non-radiative recombination centers or extended defects occurs as a result of aluminum doping.
Electroplating of Gold-Tin Solder for Optoelectronic Applications
Authors: Sun Wenzhen , Ivey Douglas G. 
Published: April 2011

ABSTRACTAu-Sn eutectic solder is widely used in optoelectronic packaging. Electroplating of Au-Sn alloys is attracting increasing research interest because of its lower cost and potential to minimize voiding in bonding layers. The challenge in developing a non-cyanide Au-Sn electroplating bath lies in bath stability and deposit composition control. In this paper a relatively stable electroplating bath is developed based on a chloride solution using citrate as a buffering agent. Direct current plating and pulse current plating are performed and compared. The effects of Au and Sn concentrations in the bath, current density, and ON time on deposit composition and microstructures are also studied.
Fracture Behavior of Epoxy-Based, Hybrid Particulate Composites
Authors: DiBerardino M. F. , Pearson R. A. 
Published: April 2011

ABSTRACTEpoxy-based, particulate composites are commonly used in packaging applications for the microelectronics industry. For example molding compounds, die attach adhesives, and encapsulant resins are all polymer matrix, particulate-reinforced composites. The mechanical behavior of these materials is a function of the type of resin, the shape and size of the reinforcing particles, the filler content, etc. In this paper, we will examine the interactions of the toughening mechanisms between rubber particles and the reinforcing particles. Hybrid-particulate composites are prepared by compounding both rubber particles and disc-shaped boron nitride particles in a bisphenol A-based epoxy cured with piperidine. Interestingly, there are combinations of rubber and reinforcing particles that lead to synergistic toughening. The underlying causes for synergistic toughening will be discussed.
Flip Chip Metallurgies for Lead-Free Solders
Authors: Korhonen T. M. , Hong S. J. , Korhonen M. A. , LI C.-Y. 
Published: April 2011

ABSTRACTThe most commonly used lead-free solders contain large amounts of tin, which makes them incompatible with the conventional Cu-based underbump metallization (UBM) schemes. The tin in the solder reacts with the copper layer of the UBM, depleting the UBM of copper and causing loss of adhesion and a weak interface. Use of new under bump metallization schemes with Ni or CuNi alloys as the solderable layer were investigated in this study. Instead of Cr, a Tibased adhesion layer was used to decrease the amount of stress in the CuNi layer. Flip chip solder joints were made in which three Sn-Bi-Ag based lead-free solders were reflowed to several UBM pads of different compositions. The resulting interfacial microstructures were examined by SEM/EDX analysis of cross-sectioned samples. The joints were also mechanically tested in fatigue and shear to assess the quality and reliability of the interface.
Modeling Complex Aftereffect Behavior in Recording Materials Using a Preisach-Arrhenius Approach
Authors: Della Torre E. , Bennett L. H. , Swartzendruber L. J. 
Published: April 2011

AbstractA Preisach-Arrhenius aftereffect model, that accurately calculates the entire relaxation process, including the linear log-time region, is used to describe some other characteristics of the time decay. The location of the peak of the decay coefficient is shown to be less than the peak of the irreversible coercivity by an amount that is a function of the standard deviation of the critical field, the fluctuating field, and the moving parameter. The model computes a magnetization decay that includes nonmonotonic behavior under certain circumstances, depending upon the applied field history. A conclusion of this paper is that procedures for accelerated testing of magnetic media are suspect.
AFM Nanoindentation as a Method to Determine Microhardness of Hard Thin Films
Authors: Bao T. , Morrison P. W. , Woyczynski W. 
Published: April 2011

AbstractThis paper presents experimental and analytical studies of AFM nanoindentation as a method to determine microhardness of hard thin films. Indentations are performed on Au, Si, and DLC using triangular pyramidal diamond probes to determine microhardness. We examined the effects of indentation force and three different methods to measure the indentation area (direct area measurement for a triangular indentation, size analysis of an inverted AFM image of the indentation, and prediction of area from indentation depth based on a tip shape function). The responses are indentation depth, projection area, and microhardness. Relationship of responses with indentation force is examined. At a low depth range, microhardness based on pyramidal shape function is erroneously higher than the other two methods. However, all three methods generally agree with each other when indentation force exceeds 16μN. Size analysis of inverted images gives more consistent microhardness with the least variability over the whole force (4∼30μN) or depth (0.5∼70 nm) range. Tip shape models are developed to predict microhardness. The ellipsoidal tip model is a good approximation at low depth ranges, while the pyramidal model works better for deeper indentations. The force vs area curves are also significantly nonlinear which can distort the hardness measurements.
Synthesis of Nanostructured Iron Oxide(III) Powders by Rapid Expansion of Supercritical Fluid Solutions
Authors: Burukhin A.A. , Churagulov B.R. , Oleynikov N.N. , Kolen'Ko Yu.V. 
Published: April 2011

ABSTRACTNanostructured a-Fe2O3 powders were generated by rapid expansion of supercritical fluid solutions (RESS, T=773 K, P=100 MPa) and by rapid thermal decomposition of precursors in solution ( RTDS, T=623 K, P=100 MPa) on lab RESS-setup from 0,040 M and 0,10 M aqueous solutions of Fe(NO3)3. The size of subcrystallites is about 22-29 nm. Comparison of reactivity of α-Fe2O3 powders in a model solid state reaction between a-Fe2O3 powders (generated by RESS from 0,040 M solution) and Li2CO3 (mole ratio 1:1) with literature data on a-Fe2O3 powders produced by other methods shows that its reactivity is markedly higher. A basic essence possibility of zinc ferrite ZnFe2O4 formation immediately at the stage of the rapid expansion (T=773K; P=100 MPa) of a supercritical aqueous solution of zinc and iron nitrates (molar ratio Zn:Fe=1:2; C=0. 1 M) was shown.