bluuebunny/crossref_metadata_2025_split huggingface dataset:
Incorporation of nano-particle sites in polymer matrix by Metal ion imprinting
Authors: Singh Alok , Puranik Dhananjay , Guo Yan , Zabetakis Daniel , Chang Eddie L. 
Published: April 2011

ABSTRACTWe present an approach for synthesizing polymer matrices that have been pre-organized to bind metal ions selectively. The acyclic chelator, triethylenetetramine, was modified to include a polymerizable functional group and then complexed with a target metal ion. Unlike macro cyclic ligands, the acyclic chelators have the flexibility to form chelation rings that are dependent on metal-ion size and geometry. Therefore, we have used the complexation step as a means to optimize the chelator conformation for a particular metal ion. The resulting complex was then cross linked with the matrix monomer, TRIM (2-ethyl-2-(hydroxymethyl)propane-1,3-diol trimethacrylate), to provide a rigid polymer matrix for stabilization of the conformation for the metal-ligand site. These sites were then tested for selectivity towards the imprinted metal ion. Unlike imprinting for larger molecules, the relatively smaller size of the metal ions facilitated their access to the imprinted sites embedded in the porous polymers. In addition to metal-binding applications, polymeric materials doped with metal nanoparticles and metal ions can exhibit interesting physical, chemical, optical and electronic properties.
Microscopic role of a surfactant in epitaxial crystal growth
Authors: Lee Seung Mi , Lee Young Hee 
Published: April 2011

ABSTRACTWe have investigated the kinetic role of a surfactant in the epitaxial crystal growth of Si/Ge using an ab initio molecular dynamics approach. We find that adsorption and diffusion of an adatom on monohydride Si(001) surface is drastically altered from that on a clean surface in several ways. We particularly emphasize the role of H as a surfactant, and this is further compared to typical group V materials.
Mechanically assisted surface modification of polymer particles with superfine calcium phosphates
Authors: Liao Jiefan 
Published: April 2011

ABSTRACTA mechanical route plays an important role in particulate coatings and synthesis. A type of particulate surface modification, i.e., oriented coating of fine particles onto the surface of a core particle, is proposed. For achieving this concept, the author has developed a two-step process involving mechanical and chemical methods. As an example, needle-like dicalcium phosphate fine particles were coated, in a standing-up state, onto the surface of nylon-12 core particles (avg 50um). The effect of the crystal structure of dicalcium phosphate on the particulate oriented coating was investigated.
Effects of Heavy-Ion Cascade Volume on the Suppression of Radiation-Induced Segregation in Alloys
Authors: Giacobbe M. J. , Rehn L. E. , Lam N. Q. , Okamoto P. R. , Funk L. , Baldo P. , McCormick A. , Stubbins J. F. 
Published: April 2011

ABSTRACTThe interactions of cascade remnants with freely migrating defects (FMDs) during dual light and heavy-ion irradiations in Cu-lat.%Au at 400°C were investigated using Rutherford backscattering spectrometry. Near-surface Au depletion driven by 1.5-MeV He ion irradiation was suppressed by concurrent bombardment with 1.2-MeV Ag ions. The dual irradiation effect suggests that shortlived cascade remnants created by heavy ions act as recombination centers for FMDs, reducing radiation-induced segregation (RIS). The effects of the total cascade volume generated by heavyion beams on the suppression of RIS were examined. The investigation revealed when 800-keV Cu and 1.2-MeV Ag ion beams produce nearly the same total cascade volume per second, their suppression effects on 1.5-MeV He-induced Au transport are also nearly equal even though the total cascade volume produced per ion for each are different. This result indicates that the suppression effect of cascade remnants produced by heavy ions depends on the total cascade volume induced per unit time and not on the total cascade volume per ion generated by individual ions of different mass and energy.
Characterization of Vacancy-Type Defects in Ion Implanted and Annealed SiC by Positron Annihilation Spectroscopy
Authors: Anwand W. , Brauer G. , Coleman P. G. , Skorupa W. 
Published: April 2011

ABSTRACTNew examples of characterization of vacancy-type defects in ion implanted and annealed SiC by the established technique of slow positron implantation spectroscopy are presented. In particular, the estimation of the depths of damaged regions and their change (a) after post-irradiation annealing, or (b) due to variation of substrate temperature during implantation, is addressed.
Oxide and Nitride Formation and Segregation of Metals During Oxygen and Nitrogen Bombardment of Silicon
Authors: Williams J. S. , Petravic M. , Conway M. , Fu L. , Chivers D. J. 
Published: April 2011

ABSTRACTThis study compares oxide and nitride formation during oxygen and nitrogen bombardment of Si. Ion bombardment is carried out both in a SIMS machine and in a conventional implanter at various temperatures. Stoichiometric SiO2 and slightly N-rich Si3N4 are formed during bombardment even at cryogenic temperatures. Implanted metals were found to have a strong tendency to be segregated at a moving Si-SiO2 interface during oxygen bombardment but little segregation is observed at a Si-Si3N4 interface.
Modeling Collision Cascade Structure of SiO2, Si3N4 and SiC using Local Topological Approaches
Authors: Jesurum C. Esther , Pulimt Vinay , Hobbs Linn W. , Berger Bonnie 
Published: April 2011

ABSTRACTMany crystalline ceramics can be amorphized within high-energy collision cascades whose overlap leads to global structural amorphization. Because the structural rearrangements amount to topological disordering, we have chosen to model these rearrangements using a topological modeling tool as an alternative to molecular dynamics simulations. We focus on the tetrahedral network compounds SiO2, Si3N4, and SiC, each compound comprising corner-sharing tetrahedral units, because they represent increasingly topologically constrained structures. SiO2 and SiC are easily amorphized experimentally, whereas Si 3N4 proves very difficult to amorphize. In this model, we consider the tetrahedron as the base unit, whose identity is largely retained throughout. In a collision cascade, all bonds in the neighborhood of a designated tetrahedron are broken, and we reform bonds in this region according to a set of local rules appropriate to crystalline assembly, each tetrahedron coordinating with available neighboring tetrahedra (insofar as is possible) in accordance with these rules. We generate fairly well connected amorphized structures for SiO2, but run into underconnected networks for Si3N4 and SiC which are irreparable without rebreaking and reforming primary tetrahedral bonds. The resulting structures are analyzed for ring content and bond angle distributions for comparison to the crystalline precursors.
Ion Beam Effects on the Formation of Semiconductor Nanoclusters
Authors: Schiestel S. , Carosella C. A. , Stroud R. , Guha S. , Cotell C. M. , Grabowski K. S. 
Published: April 2011

ABSTRACTSilicon rich silica films were deposited by coevaporation of silica and silicon with and without simultaneous ion bombardment. The Si-silica ratios are correlated to changes of index of refraction and shifts in an asymmetric stretching mode IR absorption. Photoluminescence between 550 and 600 nm is observed for all films which is attributed to SiO2 defects. After annealing this photoluminescence peak shows a shift to 750 nm and an increase in intensity, indicating the formation of silicon nanoclusters. This effect is more pronounced for samples prepared without ion beam treatment. ERD measurements show a correlation of photoluminescence with the presence of hydrogen in the films. The microstructure of these films were investigated by TEM. Photoluminescence from the Si nanoclusters in the films is optimized when the arrival rate of Si/silica is slightly less than 0.4.
Limiting Factors of Backside External Gettering by Nanocavities and Aluminum-Silicon Alloying in Silicon Wafers
Authors: Gay Henquinet N. , Martinuzzi S. 
Published: April 2011

AbstractFloat zone silicon single crystalline wafers are submitted to He ion implantations at various energy levels and fluences in the ranges 40 to 120 keV and 1016 to 1017 cm−2, respectively. Cavities are formed after annealing at 900°C for 1 h in argon. Al-Si gettering results from the deposition of a backside 1 µm thick Al wafer and annealing at 900'C for 4 h in argon. The wafers are voluntarily contaminated by 1014 to 1017 cm−3nickel atoms and diffusion length of minority carriers is determined by SPV technique and measured before and after gettering.It is found that gettering by cavities works fairly well provided the fluence is 1017 cm−2. The gettering efficiency decreases in heavily contaminated samples suggesting that the capture of impurities by the cavities is limited by the saturation of their internal surface. Al-Si alloying appears more efficient at higher contamination levels. This is most likely due to the high solubility of metal atoms in the liquid Al-Si alloy formed during the annealing.
Characterisation of the Subthreshold Damage in MeV Ion Implanted p Si
Authors: Fatima Shabih , Wong-Leung Jennifer , Fitz Gerald John , Jagadish C. 
Published: April 2011

AbstractSubthreshold damage in p-type Si implanted and annealed at elevated temperature is characterized using deep level transient spectroscopy (DLTS) and transmission electron microscopy (TEM). P-type Si is implanted with Si, Ge and Sn with energies in the range of 4 to 8.5 MeV, doses from 7 × 1012to 1×1014cm−2and all annealed at 800°C for 15 min. For each implanted specie, DLTS spectra show a transition dose called threshold dose above which point defects transform in to extended defects. DLTS measurements have shown for the doses below threshold, a sharp peak, corresponding to the signature of point defects and for doses above threshold a broad peak indicating the presence of extended defects. This is found to be consistent with TEM analyses where no defects are seen for the doses below threshold and the presence of extended defects for the doses above threshold. This suggests a defect transformation regime where point defects present below threshold are acting like nucleating sites for the extended defects. Also the mass dependence on the damage evolution has been observed, where rod-like defects are observed in the case of Si and (rod-like defects and loops) for Ge and Sn despite the fact that peak concentration of vacancies for Ge and Sn are normalized to the peak number of vacancies for Si.
Characterization of a Metastable Defect Introduced In Epitaxially Grown Boron Doped Si by 5.4 Mev α-Particles
Authors: Mamor M. , Auret F.D. , Goodman S.A. , Meyer W.E. 
Published: April 2011

AbstractDeep level transient spectroscopy (DLTS) was used to examine the metastability of a defect configuration in epitaxially grown boron-doped p-type Si. We report the detection of a new metastable defect Hα2 in p-Si following room temperature alpha particle irradiation. DLTS measurements coupled with bias-on/bias-off cooling cycles were used to study the annealing and introduction kinetics of this metastable defect. After removing Hα2 by zero-bias annealing at room temperature, it was re-introduced by reverse bias annealing in the 240-265 K temperature range under predominantly first order kinetics. The energy level and apparent capture cross section, as determined by DLTS, were E,+ 0.43 eV and 1.4 × 10−15 cm2, respectively.
A Nonvolatile MOSFET Memory Device Based on Mobile Protons in the Gate Dielectric
Authors: Vanheusden K. , Warren W.L. , Fleetwood D.M. , Devine R.A.B. , Draper B.L. , Schwank J.R. , Shaneyfelt M.R. , Wlnokur P.S. 
Published: April 2011

AbstractEver since the introduction of the metal-oxide-silicon field-effect-transistor (MOSFET), the nature of mobile and trapped charge in the oxide layer has been studied in great detail. For example, contamination with alkali ions such as sodium, causing instability of the flat-band voltage, was a major concern in the early days of MOS fabrication. Another SiO2 impurity of particular interest is hydrogen, because of its beneficial property of passivating charge traps. In this work we show that annealing of Si/SiO2/Si structures in forming gas (Ar:H2; 95:5) above 400 °C can introduce mobile H+ ions into the SiO2 layer. These mobile protons are confined within the oxide layer, and their space-charge distribution is well controllable and easily rearrangeable by applying a gate bias, making them potentially useful for application in a reliable nonvolatile MOSFET memory device. We present speed, retention, endurance, and radiation tolerance data showing that this non-volatile memory technology can be competitive with existing Si-based non-volatile memory technologies such as Flash.The chemical kinetics of mobile-proton reactions in the SiO2 film are also analyzed in greater detail. Our data show that the initial buildup of mobile protons during hydrogen annealing is limited by the rate of lateral hydrogen diffusion into the buried SiO2 films. The final density of mobile protons is determined by the cooling rate which terminates the annealing process and, in the case of subsequent anneals, by the temperature of the final anneal. To explain the observations, we propose a dynamical equilibrium model. Based on these insights, the incorporation of the proton generation process into standard semiconductor process flows is discussed.
Role of n-Type Codopants on Enhancing p-Type Dopants Incorporation in p-Type Codoped Znse
Authors: Yamamoto T. , Katayama-Yoshida H. 
Published: April 2011

AbstractWe propose materials design for the fabrication of low-resistivity p-type ZnSe crystals using a new doping method which involves simultaneous codoping of both n- and p-type dopants, based on the ab initio electronic band structure calculations. We have clarified that while doping of acceptor dopants, Lizn and Nse, leads to the destabilization of the ionic charge distributions in p-type ZnSe crystals, doping of donor dopants, Inzn, ClSe or ISe gives rise to n-type doped ZnSe with high donor concentration due to a large decrease in the Madelung energy. The codoping of the n- and p-type dopants (the ratio of their concentrations is 1:2) enhances the incorporation of the acceptors in p-type ZnSe crystals due to a decrease in the Madelung energy, resulting in the formation of the p-n-p complexes which occupy nearest-neighbor sites. It results in an increase in the net carrier densities and the hole mobility due to a change in the scattering mechanism from that caused by long-range Coulomb scatters to that by short-range dipole-like ones
Novel, Matched CTE Integrated Substrates for Power Electronics
Authors: Kowbel W. , Xia X. , Bruce C. , Withers J. C. 
Published: April 2011

ABSTRACTRapid advances in high power electronic packaging require the development of new heat-sink/substrate materials. Advanced composites designed to provide thermal control as well as improved thermal conductivity have the potential to provide benefits in the removal of excess heat from electronic devices. Carbon-carbon (C-C)composites are under consideration for numerous electronic packaging applications. A new manufacturing process has been developed to produce high thermal conductivity (400 W/mK) C-C composites at greatly reduced cost (less than $50/lb). However, low CTE (0.25 × 10−6cm/cm °C) of C-C composites results in reduced fatigue life in chipon- board (COB) applications with silicon chips (CTE ≈ 2.6 × 10−6 cm/cm °C). A novel process was developed to convert the carbon matrix into the SiC matrix which retains the overall high composite thermal conductivity. This novel technology is well-suited for COB applications. Several types of coatings, such as CVD AIN, CVD Si and a polymer slurry-based low dielectric coating were applied to the C-SiC composite. Processing schemes were developed to produce crack-free coatings. Metallization of the dielectric coating was performed for the process integration with electronic devices. Thus, integrated substrates for power electronics were fabricated without the need of conventional metal/ceramic joining and associated high stresses. The properties of this new composite material for power electronics substrates are presented.
Experimental Investigation on Interfacial Adhesion in Microelectronic Assemblies
Authors: Dai Xiang , Brillhart Mark V. , Ho Paul S. 
Published: April 2011

ABSTRACTIn this paper, we report recent studies on interface adhesion in flip-chip packaging. The adhesion energies of underfill interfaces found in typical flip-chip packaging pplications are characterized and presented using a racture-mechanics approach. The effects of underfill formulations and changes in polymer top-layer on PCB and chip passivation are also evaluated. The effects of underfill organosilane content, ubstrate surface chemistry and morphology, and underfill filler content are discussed in terms of fundamental mechanisms of adhesion.
Efficient Interfacial Design - A Multidisciplinary View
Authors: Shih C. F , Chen W. T. , Cotterell B. , Lahiri S. K. , Zhang Y.W. 
Published: April 2011

ABSTRACTOne of the most important mechanical features in microelectronic packaging is the nterface. Recent developments in modelling interfacial fracture and the easurement of interfacial toughness relevant to microelectronic packaging are discussed.
Adhesion and Subcritical Debonding of Polymer Interfaces for Microelectronic Packaging
Authors: Snodgrass J. M. , Hotchkiss G. , Dauskardt R. H. 
Published: April 2011

ABSTRACTTechniques are discussed for evaluating both critical interface adhesion values as well as the sub-critical debond behavior of polymer/silicon and polymer/polymer interfaces. Sub-critical debonding behavior is expected to be most relevant in predicting the in-service lifetime of microelectronic packages. Our research characterizes the debonding of a benzocyclobutene overlayer, as well as a technologically relevant epoxy underfill/polyimide/silicon interface system. Adhesion values are measured in a double cantilevered beam (DCB) and four-point bend fracture mechanics geometries by driving a stable debond along the relevant interfaces. The effect of temperature on subcritical debonding in an underfill/polyimide interface is described. Issues of crack path selection involving the selection of microstructurally weak paths in the layered system are considered.
Chromium Distribution in CoCrTa/Cr Longitudinal Recording Media
Authors: Wittig J.E. , Nolan T.P. , Sinclair R. , Bentley J. 
Published: April 2011

AbstractThe current study of CoCr12Ta4/Cr longitudinal recording media combines high resolution electron microscopy (HRTEM) with nanoprobe energy dispersive spectroscopy (EDS) and energy-filtered imaging (EFTEM) to correlate the Cr distribution with specific microstructural features. EFTEM images show Cr enrichment at grain boundaries, both random angle boundaries and 90° bicrystal boundaries. Cr segregation within grains is also observed in the elemental maps. This intragrain segregation often occurs at a series of defects that may define separately nucleated grains having 00 misorientation. Nanoprobe EDS measurements indicate that these defects contain localized concentrations of 25 to 30 % Cr. The random angle grain boundary Cr concentration occurs with a wide range, 19 to 36 at% (mean 22%) whereas the more crystallographically related 900 boundaries contain less Cr with less variation, 15 to 21 at% (mean 17% Cr). Composition profiles across grain boundaries using both nanoprobe EDS and EFTEM images show the full-width-half-maximum of the segregation to be approximately 4 nm, with Cr depleted regions next to the grain boundary having less than 7 at% Cr. The Ta concentration revealed no statistical evidence of segregation.
The Application of Amine - Quinone Polymers in High Density Recording Media for Improved Corrosion Protection
Authors: Sharma Rahul , Warren G. W. , Nikles D. , Hu Y. , Street S. 
Published: April 2011

AbstractHigh density, metal particle recording media consists of micron-sized iron particles in a polyurethane based polymer binder. In order to improve the corrosion resistance of the particles, two new amine-quinone (AQ) polymers, AQPU15 and AQPU100, have been investigated. Electrochemical impedance spectroscopy (EIS) was used to evaluate the corrosion behavior of iron substrates coated with two different thicknesses of each polymer. Results showed that the AQ polymers provide better protection compared with commercial polyurethane. The nature of the interaction at the polymer/metal interface has been investigated by FTIR-RA and XPS, which indicate that bonding probably occurs through the n system of the AQ functional group and the nitrogen of the soft segment, and through the quinone carbonyl functional group.
Metalorganic Chemical Vapor Deposition of Magneto-Optical Ce:YIG Thin Films
Authors: Li Yi-Qun , Cherif Mondher , Huang Jankang , Liu Wayne , Chen Qiushui 
Published: April 2011

AbstractThe deposition technologies of rare-earth substituted yttrium iron garnet (RE:YIG) thin films with a large Faraday rotation and their applications are briefly overviewed. Highly cerium substituted YIG films were successfully deposited on (111) GGG, (211) GGG, (100) MgO, and MgO buffered GaAs and InP substrates by single-liquid-source metalorganic chemical vapor deposition. Ce-YIG thin films can be epitaxially grown on lattice matched GGG substrates at a temperature as low as 600°C. They have excellent optical and magnetic properties along with high Faraday rotations. The films deposited on single crystal (100) MgO substrates are polycrystalline and have good magnetic properties. Sputter deposited MgO buffer layer was demonstrated for preventing the decomposition and chemical reaction of GaAs and LnP substrates resulting in successful deposition of YIG films on GaAs and InP substrates at a substrate temperature of 550°C. The films grown on MgO buffered GaAs substrates possessed good magnetic properties.
Integration of Yttrium Iron Garnet Films via Reactive RF Sputtering Bethanie
Authors: Stadler J. H. , Gopinath Anand 
Published: April 2011

AbstractThis work aims to equip integrated optical circuits with important magneto-optical devices, such as isolators, that are currently available only as discrete components. Reactive rf sputtering was used to grow cerium-doped yttrium iron garnet films onto a variety of substrates, including SiO2-buffered Si, fused Si02 and MgO. MgO was used because it has proven to be a good buffer material for semiconducting substrates. Ce-doping was not effective via reactive sputtering due to a scale which formed on the Ce metal that prevented sufficient contact with the rf target. The films were amorphous as deposited. Stoichiometric Y3Fe5O12 films yielded smooth, polycrystalline garnet films upon annealing. A study of the effect of fluctuations in the Y:Fe ratio revealed that oxygen content is important for the prevention of secondary phases. Therefore, a high oxygen content should be used in the sputtering gas and subsequent annealing should be performed in oxygen.