bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrical Characterization of Polysilicon-to-Silicon Interfaces
Authors: Crabbé E. F. , Hoyt J. L. , Pease R. F. W. , Gibbons J. F.
Published: March 2011

The structural properties of the polysilicon-to-silicon interface affect the electrical characteristics of devices with polysilicon contacts. The current characteristics of advanced bipolar transistors with polysilicon base and emitter contacts are very sensitive to the presence of interfacial oxides and segregated dopants. Hence, bipolar transistors provide an excellent tool for studying the effects of different interfaces on minority carrier transport. The transport of majority carriers through polysilicon-to-silicon interfaces is best investigated with contact resistance structures. In this paper, we review the correlation between interface morphology and the electrical properties of a variety of interfacial layers, ranging from native oxides to chemical oxides or thermal nitrides. Measurements on both npn transistors and contact resistance structures provide quantitative information on the trade-off between base current (i.e. current gain) and emitter resistance. Within this constraint, a variety of electrical characteristics can be obtained by tayloring the nature of the polysilicon-to-silicon interface to the device application of interest.
A Model for Dopant Pile-Up at the Interface in a Self-Aligned Polysilicon-Emitter Process
Authors: Burk Dorothea E. , Yung Shuy-Young
Published: March 2011

A model for dopant pile-up in conjunction with a self-aligned polysilicon-emitter process model is presented that accurately predicts the total dopant profiles of the polysilicon layer, the interfacial pile-up and the underlying emitter, taken from SIMS measurements. The pile-up model assumes that, after the dopant is implanted into the polysilicon layer and instantaneously redistributes there during the anneal, the dopant diffuses from its polysilicon source into the interfacial and underlying base region. In the disordered interfacial region, the dopant transport occurs by hopping, with a, certain fraction of dopant sticking in vacant sites. The model for dopant pile-up is implemented into SUPREM III. As further support, device simulations, using the respective electrically active dopant profiles, are found to be in good agreement with measurements on self-aligned phosphorus-implanted transistors.
Resistivity and Carrier Mobilities in Heavily Doped Polycrystalline Silicon Thin Films
Authors: Kim Dae M. , Qian Feng , Bickford Charles U. , Yu Simon
Published: March 2011

Electrical conduction data from heavily n and p-doped polysilicon thin films are presented. The sheet resistance in the range from 1 kΩ/□ to 100 Ω/□ is characterized over temperatures from 20°K to 450°K. It is shown that the polysilicon resistivity, larger than the corresponding crystalline value by a factor∼ 10 in the same doping range, is temperature insensitive. This larger resistivity is correlated to the degree of dopant activation and the mobility. The measured mobility varying from 8 to 20 cm 2/V.s is smaller than the corresponding crystalline value by a factor 10 ∼ 3.
Deposition and Characteristics of Polysilicon Films for Integrated-Circuit Applications
Authors: Kamins Ted
Published: March 2011

The deposition conditions used to form polysilicon layers are determined to a large extent by the geometry of the reactor used to deposit the films. The structure of the films and the electrical behavior of devices incorporating the polysilicon layers are, in turn, influenced by the deposition conditions. Operation in the reaction-rate limited regime is necessary for film uniformity in a high-volume reactor; this is achieved by operating at low temperatures and low pressures. The temperature gradient often used in this reactor changes the structure of the deposited films, and cannot be used for devices which depend sensitively on the structure. Diffusion in polysilicon is influenced by the grain boundaries and, consequently, depends sensitively on the deposition conditions. The electrical properties of devices with their active layers within the polysilicon layer itself depend strongly on the structure of the polysilicon. Even conventional MOS transistors in which the polysilicon serves only as a conducting electrode can be affected by the structure of the polysilicon. Therefore, the deposition conditions of the polysilicon films and the resulting structure must be considered to obtain the desired electrical properties in the devices being fabricated.
Diffusion of Atoms Implanted in Poly Silicon Layer on Insulator
Authors: Takai M. , Izumi M. , Yamamoto T. , Kinomura A. , Gamo K. , Minamisono T. , Namba S.
Published: March 2011

Diffusion of arsenic implanted in poly-silicon on insulator structures after furnace and rapid thermal annealing (RTA) has been investigated by Rutherford backscattering (RBS) and Hall effect measurements. The diffusivity for As in poly–Si on insulator is represented by D = 3.12 × 104 exp (− 3.86/kT) cm/sec for the tail region after both RTA and furnace annealing and D = 34.0 exp (− 3.42/kT) cm2/sec for the peak region after RTA. Poly–Si layers after implantation and annealing were found to have tensile stresses of 3.0 – 4.0 kbar.
Phosphorus Diffusion in Polycrystalline Silicon: Monte Carlo Simulation of Experimental Diffusion Profiles
Authors: Lavine J. P. , Lee S.-T. , Black D. L. , Losee D. L. , Jarman C. M.
Published: March 2011

Phosphorus ions were implanted into silicon layers deposited by low pressure chemical vapor deposition onto thermally oxidized silicon substrates. Thermal anneals diffused the phosphorus and the resulting depth profiles were determined by secondary-ion mass spectrometry (SIMS). Transmission electron microscopy shows that the polysilicon layers have a multi-layer pattern of grains. The phosphorus profiles are fit by a Monte Carlo simulation technique that includes both grain and grain-boundary diffusion. The grain-boundary diffusion coefficient is found to be thermally activated with an activation energy of 3.3 eV.
Determination of the Nitrogen Content of as-Implanted and Annealed SIMOX Substrates
Authors: Kilner J.A. , Chater R.J. , Biswas S. , Hemment P.L.F. , Reeson K.J.
Published: March 2011

SIMOX substrate material from two sources, both as-implanted and annealed, have been analysed by Secondary Ion Mass Spectrometry (SIMS) to determine the nitrogen concentration in the silicon overlayer. A variety of different analytical conditions were used on two different SIMS instruments to reduce the possibility of artefacts arising from the difficulties of analysing nitrogen in these materials. The nitrogen contaminant level was found to be consistently below 5 x 1017 nitrogen atoms cm-3, for all the material analysed.
Modelling of the Pattern Formation of Thin Film Silicon Single Crystals
Authors: Shangguan D.K. , Hunt J.D.
Published: March 2011

In this work faceted cellular growth has been investigated both experimentally and theoretically. The faceted cellular growth process and pattern formation have been modelled numerically. It is found that both the growth kinetics and the solute effect play important roles in determining the faceted cellular structure.
Evaluation of Lamp Zone-Melting Recrystallization
Authors: Mertens P.W. , Wouters D.J. , Yallup K.J. , Maes H.E.
Published: March 2011

The intensity profiles of various kinds of topheaters are compared and discussed. Using the mercury-arc lamp heater experiments on polycrystalline silicon layers of thicknesses varying from 1 to 10 urn were performed. The 10 fiva layers were polished prior to recrystallization. After zone melting recrystallization they showed a strong (100) texture combined with an alignment of the [010] direction with the scan direction. By patterning 1 ¼m poly-silicon films into isolated narrow silicon stripes, the kinetic mechanism that is shown to be responsible for the alignment of the [010] direction along the scan direction could be inhibited. In this way other mechanisms that influence the orientation could be studied. Finally some electrical characteristics are presented.
Electrical Characterization of Si-SiO2 Interfaces in Thin-Film SOI Structures
Authors: Marshall T. , Arnold E. , Khan B.
Published: March 2011

A technique is described for performing MOS capacitance-voltage (CV) measurements on thin Si films on insulating substrates. Such measurements are complicated by the lack of a back contact in SOI structures. Design considerations for an MOS capacitor geometry appropriate for this material were made by treating the structure as a distributed RC circuit. Based on these calculations, a structure has been designed and fabricated that permits both high and low frequency CV measurement and analysis. Use is also made of the Si substrate wafer as a back gate both to provide a back channel for front-gate CV measurements and to characterize the back interface.
CV measurements and interface state calculations are presented and compared for SIMOX and laser-recrystallized materials. The experimental results are compared with those of numerical solutions to Poisson's equation.
Fast Simulation Tool For MOS/SOI Process Optimization
Authors: Paelinck P. , Vancauwenberghe O. , Wiele F. Van de
Published: March 2011

A fast simulation tool for MOS/SOI process optimization has been developed.lt solves Poisson's and one carrier current density equations in the one-dimensional case. NMOS and PMOS transistors characteristics in the linear region are reliably computed over a wide range of voltages. Moreover, special attention has been paid for threshold voltage (calculated by extrapolating the inversion charge as a function of front gate voltage ) and subthreshold current calculation. Therefore, process parameters can be easily selected in order to get enhanced device capabilities.
Cross-Sectional TEM Study of Three-Dimensional MOS Devices
Authors: Park Kyung-Ho , Sasaki T. , Iwai T. , Hasegawa M. , Sasaki N.
Published: March 2011

This paper describes cross-sectional transmission electron microscopy (TEM) observation on finished 3-D MOS devices, fabricated with a laser-recrystallized SOI. The laser-recrystallized SOI contained crystal defects such as micro-twinning, grain boundaries and dislocations. It is also clearly shown that the interface roughness between the gate oxide and SOI is as much as 20 nm height, in where the interface is very smooth between the gate oxide and bulk silicon.
Influence of the SOI Surface Morphology on Crystal Orientation and Device Characteristics
Authors: KUNIO Takemitsu , OYAMA Ken-Ichi , ENOMOTO Tadayoshi
Published: March 2011

The surface morphology of SOI has been studied. The surface is very wavy and contains protrusions. Crystal orientations for SOI without protrusions were close to (100), while those for SOI with protrusions were close to either (111) or (101). The angle of orientation rotation for SOI without protrusions was less than 5 degrees over a 600um long SOI stripe, while the angle of SOI with protrusions was about 30 degrees. Threshold voltages of pMOSFET with protrusions in the channel were generally larger than those without protrusions in the channel.
Helium-induced porous layer formation in Silicon.
Authors: Veen A. Van , Griffioen C.C. , Evans J.H.
Published: March 2011

The annealing behaviour of helium bubbles formed by ambient temperature 10 keV helium implantation into silicon has been studied using transmission electron microscopy (TEM) and helium desorption spectroscopy (HDS). Although the TEM results indicated conventional bubble annealing processes due to bubble migration and coalescence, the HDS data demonstrated that helium can permeate out of bubbles in silicon around 1000K to leave behind empty cavities, thus giving a porous layer coincident with the original helium implant profile.

The addition of a low dose of implanted oxygen to the silicon-helium samples has been shown to strongly improve the stability of the porous layer, at least up to 1300K.
TEM Observations of Silicon-on-Insulator Structures Formed by Nitrogen Implantation with Annealing at 1405°c.
Authors: Meekison Cd. , Booker G.R. , Reeson K.J. , Hemment P.L.F. , Celler G.K.
Published: March 2011

(100) silicon waferSgWere-implanted with 200keV N ions to doses of 0.95 and 1.1x1018 cm-2 at a temperature of 520°C, and then annealed at 1405°C for 30 minutes. We report here observations of the resulting microstructures. A buried ɑ-Si3N4. layer and a good quality silicon overlayer were found. Evidence of cavities in the Si3N4. layer was found in the higher dose sample. Our results suggest that the cavities are associated with the delamination which sometimes occurs during annealing.
Silicon and Silicon Dioxide Thermal Bonding
Authors: Black Robert D. , Hall Ernest L. , Lewis Nathan , Gilmore Robert S. , Arthur Steven D. , Lillquist Robert D.
Published: March 2011

The quality of the bond produced after mating oxidized and/or unoxidized silicon wafers has been studied using acoustic microscopy, infrared transmission thermographs, and transmission electron microscopy. The acoustic microscopy revealed that a significant number of unbonded regions (gaps) remain at the bond interface after bonding in oxygen, nitrogen, or high vacuum, and then annealing. These gaps could be virtually eliminated by a subsequent hyperbaric annealing step. The thermal imaging was found to have insufficient resolution to give a detailed picture of the bond quality. Transmission electron microscopy showed that an excellent bond could be produced when bonding clean silicon wafers, with only very small oxide or void bubbles present at the interface. Bonding two oxidized wafers resulted in a buried oxide layer with no detectable bond line. Mating an oxidized wafer to an unoxidized wafer produced a bonded silicon/oxide interface which was nearly indistiguishable from the wafer/thermal oxide interface.
Enhancement of Lateral Solid Phase Epitaxial Growth of Si on SiO2 with 31P Implantation
Authors: Pai C. S. , Bean J. C. , Cerullo M. , Short K. T. , White A. E.
Published: March 2011

The lateral solid phase epitaxial growth of amorphous Si on SiO2 patterns with 31P implantation is studied. By implanting 31P into only the surface region of the sample to form a doped channel, the Si growth rate is enhanced and the random crystallization of Si is suppressed. The maximum length of lateral solid phase epitaxial Si obtained from samples with the doped channel (∼9μπι) is a factor of 3 more than that of the undoped sample. This Si on SiO2 film has a low dopant concentration after the highly doped channel is removed and should be useful for device application.
The Cracking and Decohesion of Thin Films
Authors: Evans A. G. , Drory M. D. , Hu M. S.
Published: March 2011

The cracking and decohesion of thin films can be characterized by critical values of a non-dimensional parameter governed by the residual stress, the film thickness and a fracture resistance. This article describes the status of understanding concerning the magnitude of this number for various types of adherent film on either brittle or ductile substrates. Important effects of elastic properties, substrate thickness and yield strength are described.
Energy-Free Bonding of Materials with Fine Controlled Surfaces in Ultrahigh Vacuum
Authors: Kashib Y. , Machida K. , Okuda T. , Shimada W. , Nakata S.
Published: March 2011

Bonding phenomena with clean and smooth surfaces at room temperature (293 K) in ultrahigh vacuum has been studied. The metal surfaces, finished to required smoothness in nm level, were bombarded by Ar ions to remove surface contaminants. Then, two cleaned surfaces were put together. Interaction of silver and copper was examined by SEM, AES, and TEM. In order to observe the fundamental phenomena, bonding was attempted between a silver disk with a flat surface and a copper sphere 80 pm in diameter. A bonding area of about 40 μm2 was confirmed under slight load at 293 K. Strong bonds were achieved and the fracture took place almost completely in silver bulk. Furthermore, it was found that the bonding area obtained by the process was much larger than the one derived from conventional plastic theory.
Deformation Behavior of Leadless 60% Pb–40% Sn Solder Joints
Authors: Subrahmanyan Ravichandran , Stone Donald , Li Che-Yu
Published: March 2011

Room temperature deformation data of leadless solder joints are reported. The joints were sheared under cyclic, displacement controlled loading at frequencies between 0.001 and 0.01 Hz. A microplastic model was utilized to simulate the stress-strain loops, which demonstrated a pronounced Bauschinger effect. The implications of microplasticity on fatigue life of solder joints are discussed. This phenomenon must be taken into account in an accurate prediction of solder deformation at low strain ranges.
Shall Diensions or Low Dielectric Constant the Competing Approaches to High Density Interconnect
Authors: Balde W. John
Published: March 2011

EXTENDED ABSTRACT

Ten years ago, the conventional wisdom as cited by Rex Rice and others was that interconnect wiring on a silicon chip was much less expensive than interconnections on a ceramic hybrid, a printed circuit board, or cable interconnect. That led to a major emphasis on increasing the size and complexity of the silicon chip, with the other interconnect media left for the overflow or leftovers that could not be placed on the chip.

A major change of thinking was triggered by Knausenberger and Schaper of AT&T (1), with the realization that costs normalized per inch of wire length were nearly identical for all forms of interconnect. Literally an inch of interconnection circuit costs the same whether that circuit was on silicon or on ceramic, whether that circuit was on a printed circuit board or in cable.

If the only important criteria is the length of the interconnect, then a system or a board of the smallest size and area for a given circuit will have the shortest path lengths and the lowest cost. The dominant criteria is the area of the interconnection medium that carries the active silicon.
Nonresonant Third-Order Nonlinear Polarizability in Linear Conjugated Molecules
Authors: Stevenson S. H. , Donald D. S. , Meredith G. R.
Published: March 2011

Crude pictures relating molecular features and enhancement of nonresonant second-order hyperpolarizability have been known and successfully utilized in selection and preparation of materials for nonlinear-optical applications for over a decade. On the other hand, other than the requirement of “electron delocalization”, such a useful picture does not exist for nonresonant third-order hyperpolarizability. In pursuit of such a picture, and to obtain a better view of the range of hyperpolarizability magnitudes which might be obtainable, simple linear conjugated molecules have been synthesized and characterized. Liquid solutions of these model compounds were studied using recently developed high precision optical third harmonic generation techniques. Results of these characterizations and a new addition to the picture of structure-property relationships are reported.
Studies of Orientational Order in Monolayers of Nonlinear Optical Dye Molecules
Authors: Legrange J. D. , King L. A. , Kuzyk M. G. , Singer K. D. , Katz H. E. , Schilling M. L.
Published: March 2011

We present results of studies of orientational order of Langmuir-Blodgett monolayer and multilayer films based on second harmonic generation and linear absorption measurements. Two new compounds, a tricyanovinyl aniline and a tricyanovinyl azo dye, both possessing large second order molecular susceptibilities have been synthesized and transferred as monolayers from the air-water interface to solid substrates using the Langmuir-Blodgett technique. The azo dye is a superior Langmuir-Blodgett material, forming films which are chemically and structurally stable. Multilayers of this compound show an enhancement in polar orientational order with thickness, as observed in the dependence of the second harmonic polarization components on number of layers.
Transmission of Electron Density Through Moieties Between Donors and Acceptors: Possible Implications for Non-Linear Optics
Authors: Wnek G. E. , Kitipichai P. , Frysinger G. , Korenowski G. M. , Gorodisher I. , Uhlmann D. R. , Wei Y.
Published: March 2011

Organic materials having aminophenyl and nitrophenyl moieties linked by various atoms or groups (S, O, SO, SO2, CH2) were prepared and their ability to generate a second harmonic was compared within the series and with urea. We find that the compound containing a sulfur bridge, 4-amino-4′-nitrodiphenyl sulfide, exhibits a powder second harmonic generation efficiency which is approximately 10x that of urea. The result is consistent with earlier spectroscopic studies which indicate that sulfur, as opposed to the other bridges studied in this series, is effective in allowing the transmission of electron density between donors and acceptors.
Nonlinear Optical Materials Based on Benzobisthiazole. Electronic Structure/Molecular Architecture/Polarizability/Hyperpolarizability Relationships Derived from π-Electron Theory
Authors: Li Dequan , Marks T. J. , Ratner M. A.
Published: March 2011

Factors contributing to the polarizability (αij) and frequencydoubling hyperpolarizability (βijk) of 2-(p-dimethylaminophenyl)-6-(pnitrophenyl) benzo(l,2-d:4,5-d′ )blsthiazole (DNBT) are analyzed via perturbation theory and the PPP-SCF-MECI π-electron model Hamiltonian. While the observable part of β (βvec) is clearly identifiable with a small number of charge transfer excitations along the molecular dipole direction, a (and by inference, the second-order hyperpolarizability γ) is more closely related to the overall size (volume) of the π-electron cloud. As a consequence, βvec is far more sensitive to molecular distortions which affect donor-acceptor charge transfer interactions than is π. The more sensitive frequency dependence of βvec can be understood in terms of the three-photon character of this nonlinearity.
Transient Photoconductivity in Polyacetylene and Polydiacetylene
Authors: Moses D. , Phillips S. , Sinclair M. , Heeger A. J.
Published: March 2011

Conducting polymers have been found to be rather good photoconductors in the sub-nansecond time regime. The TP measurement is an effective probe for determining carrier photogeneration quantum yield as well as for investigating transport mechanisms. Here, we present a short survey of our results for a few interesting polymeric systems. We start with the trans-(CH)x grown by the Shirakawa method. We then compared the TP results to those obtained from PDA-TS which currently is the only conjugated polymer in single crystal form. From this comparison, we are able to gauge the improvements in the material quality as was demonstrated by recent TP in trans-(CH)x grown by the Naarmann method
Nonlinear Optical Response of Conducting Polymers
Authors: Wu Weikang , Kivelson Steven
Published: March 2011

We compute analytic expressions for the nonlinear optical response functions for the Peierls model of a conducting polymer by using the Keldysh non-equilibrium Green's function methods. The only parameter in the model is the gap, which can be determined independently from the linear optical response. Our results for 3rd harmonic generation are in excellent agreement with experiments on polyacetylene. This constitutes strong evidence that polyacetylene is well described by a model of weakly interacting quasi-particles. Further nonlinear optical effects, which should be experimentally observable, are predicted.
Third-Order Nonlinear Optical Effects in Organic Polymeric Films
Authors: Prasad Paras N.
Published: March 2011

This paper presents some recent theoretical and experimental work carried out in the author's laboratory on the nonlinear optical properties of organic polymers. The ab initio SCF theory has been used with the finite field method to calculate the third order nonlinearity of conjugated structures in order to understand the effect of conjugation and the role of substituents. Experimental studies of third order resonant nonlinearlty in polythiophenes and cumylphenoxy phthalocyanine, the latter in the form of Langmuir-Blodgett films, are presented using femtosecond degenerate four wave mixing.
Toward Highly Oriented Conjugated Polymers for Non-Linear Optics
Authors: Smith P. , Heeger A. J. , Wudl F. , Chiang J.
Published: March 2011

The promise of conjugated polymers as fast response nonlinear optical materials has been emphasized, since the nonresonant third order nonlinear susceptibilities of these π-electron polymers are among the largest measured in any material. For example, third harmonic generation (THG) experiments have shown that for trans-polyacetylene, χ║(3)(3ω:ωω,ω) = (4± 2) × 10-10 esu, where χ║(3) refers to that component of the third order susceptibility tensor with all indices parallel to the chain direction [1]. The large nonlinear response is anisotropic and arises from the π-electrons of the conjugated polymer. The magnitude and anisotropy are comparable to results obtained from single crystals of polydiacetylene-(toluenesulfonate). Given these large χ║(3) values, it is important to develop methods for fabricating chain-aligned (oriented) conjugated polymer films which have optical quality.
Optical Threshold Elements Based on the Excited State Photophysical Properties of Molecular Materials
Authors: Potember Richard S. , Hoffman Robert C. , Stetyick Karen A. , Murphy Robert A.
Published: March 2011

The wavelengths at which indanthrone behaves as an efficient reverse saturable absorber can be changed by chemical modification of the indanthrone chromophore. Several derivatives of indanthrone have been synthesized and they have been shown to be more efficient nonlinear optical materials than the parent chromophore. In this paper we will discuss the behavior of these indanthrone derivatives, attempt to correlate the nonlinear optical properties observed in this class of compounds to modifications in the structure of the indanthrone chromophore and suggest how these nonlinear materials may be applied to all-optical switching devices.
Nonlinear Optical Properties of Polyaniline
Authors: Epstein A. J. , Ginder J. M. , Roe M. G. , Gustafson T. L. , Angelopoulos M. , Macdiarmid A. G.
Published: March 2011

Polyaniline is a family of polymers whose electronic and optical properties can be controlled through variation of the number of electrons and protons on the polymer chain. For example, the emeraldine base form of the polymer (EB) is insulating while the emeraldine salt form (ES) is metallic. We present here results for photoinduced absorption spectroscopy of the emeraldine base form of polyaniline. Unlike earlier studied polymers, the spectrum of emeraldine base contains both subgap photoinduced bleaching (at 1.8 eV) and photoinduced absorption (at 0.9, 1.4, and 3.0 eV). The existence of the bleaching peak is consistent with a model of optically excited localized molecular excitons in the emeraldine base polymer. The energies of the three photoinduced absorptions peaks and an associated interband bleaching (at energies greater than ∼3.5 eV) are in agreement with the photogeneration of polaron pairs. Laser intensity studies support that the excitons decay monomolecularly while the polarons decay bimolecularly. Picosecond time-resolved spectroscopy of the exciton decay demonstrates the rapid response of this system.
Second Harmonic Generation by Polymer Composites
Authors: Calvert P. D. , Moyle B. D.
Published: March 2011

Second harmonic generation was observed from composites consisting of 3-nitroaniline or 3-methyl-4-nitroaniline grown within a polymer matrix. In the amorphous polymers, polystyrene and poly(methyl methacrylate), the crystals formed as fine grains or needles. The intensity of the second harmonic, from Nd-YAG light at 1.06 μm, was measured as a function of the composition from 10–90 wt% of nitroaniline. The angular distribution of the light output was very dependent on the morphology of the precipitate, with a strong concentration of the output in the forward direction for samples containing locally aligned, needle-like crystals. The behaviour in SHG and in light scattering was compared.

Composites with crystalline polymers were prepared as unoriented or oriented films. Nitroanilines and potassiun dihydrogen orthophosphate were crystallised from a number of polymers. The composite structure is governed particularly by the extent of liquid phase miscibility. The potential for optical applications of these materials are discussed.
The Interaction of Borosilicate Glass and Grawodiorite at 100°C, 50 Mpa: Implications For Models Of Radionuclide Release
Authors: Savage David , RObbins Jane E.
Published: March 2011

An essential component of any assessment of HLRW geological disposal options is the quantitative prediction of radionuclide release rates from the near-field over time spans of the order of 103-106 years. Fundamental to this assessment is the investigation of the interaction of potential wasteforms with groundwater under repository conditions of temperature, pressure, and groundwater flow-rate. Consequently, many studies world-wide have been initiated to examine the kinetics of wasteform dissolution over a wide range of physical and chemical conditions. Although these studies have provided a considerable amount of invaluable data on wasteform-fluid interactions, they have tended to focus on breakdown of the wasteform itself, and not on the fate of released waste components in the nearfield. For example, effects of saturation of species in solution, precipitation of secondary minerals or amorphous gels, and the effect of host rock chemistry on the products (solid and fluid) of waste-fluid interaction have largely been ignored or even specifically excluded in laboratory experiments. This is despite growing evidence from source term modelling studies which suggest that the above processes may well be the chief factors in governing rates of radionuclide release from the near-field, bearing in mind the limited availability of ground
Utilization of Charged Particle Backscattering to Study the Near Surface Region of Glasses. Application to Depth Profiling of Lanthanium, Cerium, Thorium and Uranium Induced by Aqueous Leaching.
Authors: Trocellier Patrick , Nens Bernard , Engelmann Charles
Published: March 2011

The Rutherford backscattering technique is useful for the determination of the concentration profiles of some heavy elements in the near surface region of glasses, but is not able to provide chemical information on the elements detected.
On the Leaching Behaviour of a Simple Borosilicate Glass in a Confined Environment
Authors: Petit J.C. , Langevin Y. , Lameille J.M. , Dran J.C.
Published: March 2011

Cm-sized blocks of a simple borosilicate glass have been leached in hydrothermal conditions with various rates of water renewal. Weight loss measurements reveal that restricted water access does not slow down the dissolution rate of this particular glass as would be expected from solubility limits, but instead accelerates its destruction and its transformation into a secondary solid phase still ill-defined.
Incorporation of High-Level Wastes in Synroc: Results from Recent Process Engineering Studies at Lawrence Livermore National Laboratory
Authors: Campbell J. H. , Hoenig C. L. , Ackerman F. J. , Peters P. E. , Grens J. Z.
Published: March 2011

In October 1981 SYNROC-D was selected as the reference alternate waste form to borosilicate glass for immobilization of defense wastes. A total of eight candidate waste forms competed in this selection process and the decision of which alternate waste form to choose was based primarily on performance properties.
Isotopic Fractionation of Thorium and Uranium Upon Leaching of Monazite: Alpha-Recoil Damage Effects
Authors: Eyal Yehuda
Published: March 2011

It has been proposed recently that high-level radioactive wastes from spent nuclear reactor fuels be converted into a crystalline phosphate form prior to their disposal in geological repositories. This approach is based on the known durability in nature of the mineral monazite, (Ce,La)P0, which contains appreciable concentrations of thorium and uranium. Of significance is the demonstrated resistance of monazite to excessive metamictization, in spite of the fact that the mineral has been subjected since its formation to radiation from the radioactive disintegration of U, Th and their many intermediate decay products. Nevertheless, radiation effects on the leaching behavior of the material in possible groundwater environments must be studied in the development and testing of monazite-like phases for the long-term disposal of fission product and actinide wastes.
Thermomechanical In-Situ Experiments and Finite Element Computations
Authors: Pudewills Alexandra , MÜller Roland , Korthaus Ekkehard , KÖster Rainer
Published: March 2011

In the ultimate storage of high level wastes in rock salt thermomechanical phenomena caused by the temperature rises play an important role for elaborating the storage concept. Important factors are both large space effects concerning the repository and the geological formation and small space phenomena influencing to a considerable extent the interaction between waste blocks and the host rock. While the large space aspects are largely inaccessible to an experimental investigation, the small space effects, especially the convergence behavior of individual heated boreholes, are eligible for a systematic experimental and computational study allowing verification of available computational methods and thermomechanical material laws for rock salt.
Permeability Monitoring Technique of the Near-Field and Far-Field Interface of Underground Openings
Authors: Jakubick Alexander T. , De Korompay Victor
Published: March 2011

In July/August 1981 and February/March 1982 we sampled water for isotope analysis from water-bearing fractures of two mines in Elliot Lake. Permission for sampling was given to Ontario Hydro by Denison Mines Ltd and Rio Algom Ltd, Quirke Mine in conjunction with the CANMET Mine Safety Tests. The purpose of the investigation was to find out whether there is a relationship between the water present in some fractures in a deep mine and the shallow groundwater in the far-field of the mine. The investigation was done in co-operation with University of Waterloo.
A Combined Analytical Model for Performance Assessment of the Waste Package/ Geologic Medium Systems
Authors: Ray Asit K. , Nair Shyam , Eric Nuttall H.
Published: March 2011

Geologic waste isolation systems currently under consideration for long term containment of high-level radioactive waste is based on a set of sequential barriers to release of radionuclides. Recently, Klingsberg and Duguid and Pigford have reviewed in detail the multiple-barrier disposal concept. These barriers are the waste form, canister, buffer, overpack, backfill and geologic media. Each of these barriers acts to retard ground water penetration to the repository as well as migration of radionuclides to the biosphere.
Engineered Components for Spent Fuel Radioactive Waste Isolation Systems—are They Technically Justified?
Authors: Burkholder H. C.
Published: March 2011

In response to draft radioactive waste disposal standards, R&D programs have been initiated in the United States which are aimed at developing and ultimately using radionuclide transport-delaying (e.g., long-lived waste containers) and radionuclide transport-controlling (e.g., very low release rate waste forms) engineered components as part of the isolation system. Before these programs proceed significantly, it seems prudent to evaluate the technical justification for development and use of sophisticated engineered components in radioactive waste isolation.
Evaluation of Radionuclide Transport: Effect of Radionuclide Sorption and Solubility
Authors: Salter P. F. , Jacobs G. K.
Published: March 2011

The current strategy for the permanent isolation of nuclear wastes in the United States involves the storage of these wastes within repositories mined in deep geologic formations. In this disposal strategy, the isolation of nuclear wastes relies on a series of natural and engineered barriers to prevent the unacceptable release of radionuclides to the accessible environment. An integral part of the development of a qualified subsurface nuclear waste repository, therefore, is the assessment of the ability of these barriers to adequately prevent or retard the migration of radionuclides to the accessible environment. The Basalt Waste Isolation Project (BWIP) under guidance from the Department of Energy (DOE) is investigating the feasibility of storing nuclear w-stes in the basalts beneath the Hanford Site.
Intracoin - An International Nuclide Transport Code Intercomparison Study
Authors: Andersson K. , Grundfelt B. , Hadermann J.
Published: March 2011

Much effort is currently centred on the construction of elaborate computer programs to model the release to the biosphere of radionuclides from proposed high level radioactive waste repositories in deep geological formations. Although the lack or poor quality of background data is often emphasised, it is generally considered that by examining a wide range of possible values of the important parameters involved, likely processes are assessed or their omission and possible relevence is acknowledged. However, one factor that has been almost totally ignored is the presence of micro-organisms in deep geological formations. The common assumption is that the biosphere is limited to the earth's surface, and soil to a depth of a few metres. Recent research has shown, however, that viable micro-organisms can inhabit deep groundwaters and that the biosphere can extend to depths of at least 5 km. Examples of organisms tolerant to extreme environments are given in Table 1 although ranges are likely to be conservative due to the difficulties of culturing these organisms, which tend to have exotic nutritional requirements, and sampling them in extremely hostile environments.
The Role of Metal Ion Solubility in Leaching of Nuclear Waste Glasses
Authors: Grambow B.
Published: March 2011

The leachability of solid nuclear waste forms has been studied by many investigators to evaluate the short-term kinetics of elemental release or to determine the effects of leachant composition or other system parameters. Some general observations from these studies have included: incongruent leaching; formation of reaction layers that contain rare-earth, alkaline-earth, or transition metal elements; and apparent saturation of some elements in solution while others continue to be leached. Before these observations can be used to predict long-term performance of waste glasses under repository conditions, the mechanisms controlling the release of elements from the solid must be understood.
Evaluation of a Pyridoxalated-Hemoglobin-Polyoxyethylene Conjugate (PHP) as an Oxygen Carrying Plasma Expander in Lethal Anemia
Authors: Matsushita M. , Yabuki A. , Malchesky P. S. , Iwashita Y. , Nosè Y.
Published: March 2011

PHP, mean molecular weight of approximately 90,000 daltons, is produced by chemical modifications of outdated human red cell hemoglobin (Hb). The P50 value of PHP is 22 ± 0.7mmHg. Eleven healthy mongrel dogs were exposed to severe anemia to a hematocrit of 5 ± 2% by normovolemic exchange (ET) with PHP (n=5) or a plasma expander, Hespan (Control, n=6). Hb concentration in the preparation is 6.0 g/dl. All the animals with PHP tolerated the procedure well and have survived for 1 year at sacrifice while five of the controls died within a week (p=0.004). Reductions in hematological and coagulation parameters occurred following ET and these parameters returned to the normal ranges by 4 weeks post ET. Renal function parameters (serum urea and creatinine) remained in the normal range throughout the experimental period. A transient slight increase in the hepatic enzyme SGOT was observed. Open biopsies of major organs at 2 weeks post ET showed vacuolated cells in the liver and kidneys. Normal histology was noted at and after 3 months. Oxygen transport properties as examined by arterial-venous oxygen differences, oxygen delivery and oxygen extraction showed that PHP continued to transport oxygen up to 48 hours studied post ET. PHP functioned as effectively as red blood cells at 6 hours in oxygen delivery to the tissues. PHP effectively supported life at lethal levels of anemia and is physiologically well accepted.
Electrodes for Functional Neuralmuscular Stimulation
Authors: Lee Y. S. , Anderson W. A. , Mendel F. C. , Fish D. R. , Anderson L. M.
Published: March 2011

Electrodes for FNS were fabricated by photolithographic techniques from foils of Mo, Ta, and stainless steel with lateral dimensions of 1–3 mm and thickness of about 50 μm. More recent designs have utilized a Si carrier with either a Pt or diffused Si track terminated by Au electrodes. Biocompatibility studies conducted on frogs and rabbits indicate good stability of electrodes coated with SiO by plasma deposition. Carriers did not move after implantation and did not show signs of corrosion. The diffused Si design is now preferred since electrode tracks are sub-surface, tracks may be electrically and biologically insulated by SiO2, all fabrication steps are compatible with standard integrated circuit processing such that electronics may be integrated on the carrier with the electrode tracks, and small dimensions are easily attained.
The Application of a New Composite in Large Bone Defects using Fibrillar Collagen and HA/TCP
Authors: Uratsuji Masaaki , Bauer T. W. , Reger S. I.
Published: March 2011

The handling property and short term biological response to a new composite of fibrillar collagen (FC) and porous calcium phosphate (HA/TCP) were studied. A 4 mm by 20 mm defect was created in the femora of rabbits. The rabbits were divided into four treatment groups and sacrificed from each group at 4, 8 and 12 weeks. In each group, the defect was treated as follows: in Group I with autogenous bone marrow; in Group II with FC and HA/TCP; and in Group III with FC and HA/TCP with bone marrow in volume ratio of 3:1. In the fourth group, the defect was unfilled. The femora were excised and studied by microradiography or histology or both. The FC could improve the handling property of the HA/TCP granules. Although the composite of FC and HA/TCP was not osteoinductive, the defects in Groups II and III showed good healing at 12 weeks without signs of inflammation. The results showed the composite of FC and HA/TCP to be an effective filler for large bone defects especially when mixed with autogenous bone marrow.
Hydroxylapatite/Plaster Implantation for the Treatment of Severe Periodontal Osseous Defects
Authors: Carnevale Reynolds A. , Greco George W. , Bullard Cindy M. , Hanker Jacob S.
Published: March 2011

Infrabony defects of 230 periodontal patients have been treated surgically by implantation. These lesions of alveolar bone, up to nineteen per patient, generally displayed pocket depths of at least 8mm and were associated with teeth showing pronounced mobility. Approximately 50% of these teeth could have ordinarily been condemned to extraction. In this study, scaling, root planing, and polishing were performed and patients were instructed in oral hygiene measures prior to surgical implantation. A 1:1 mixture of dense sintered hydroxylapatite(HA) particles (OrthoMatrix HA-500) with plaster of Paris (USG Medical Grade Calcium Sulfate Hemihydrate B, containing 0.85% K2SO4) was moistened with a minimum amount of saline. The mixture was then implanted into the dried defect. After setting, the operative site was closed with silk sutures. The plaster bound the HA particles in the defects and prevented particle straying which frequently occurs when they are implanted with saline alone or with other vehicles. There was an almost immediate and sustained diminution in tooth mobility at most implantation sites. Good retention of particles was seen on physical and radiographic examination of most defects for the length of the study (5 years). Overall, there was a marked reduction in pocket depth and improvement in tissue tone and texture. Less than 1% of the teeth at the implantation sites have been lost. No significant inflammation has been observed. Increased radiopacity and resistance to probing suggest bone formation in some implanted defects. Implantation of periodontal osseous defects with the biocompatible HA/plaster composite appears to result in the clinical cessation of progressive periodontal disease.
UCSF Multichannel Cochlear Implants
Authors: Schindler Robert A. , Kessler Dorcas K.
Published: March 2011

Clinical trials with the UCSF/Storz multichannel cochlear implant began in February 1985. The final patient in this series was implanted in June 1986. The objective of the clinical trial was to evaluate the strategies developed by the UCSF implant team through neurophysiological, histopathological, and psychophysical investigations over the past seventeen years. A total of 16 patients were implanted with this four channel unit, a vocoder-based, compressed-analog system. Results are measured with a battery of speech reception tests, including routine audiometric tasks used to evaluate standard clinical populations. Assessments are administered using conventional audiologic procedures. Tests include monosyllabic word recognition (the standard clinical “speech discrimination” list) and the recognition of key words in sentences. Eleven of the 16 patients have now had their one-year postoperative evaluations, permitting observations on their performance over time. Of these 11 patients, ten (91%) are able to obtain a considerable degree of auditory speech recognition. Relative to other cochlear implant projects, this represents an extremely high proportion of the implant population achieving some level of auditory-only speech understanding. The UCSF/Storz clinical trial has helped to clarify and define the specifications for our next generation implant, an elecrically transparent sixteen channel system.
Conduction Properties in Peripheral Nerve Fibers Regenerated by Biodegradable Polymer Matrix
Authors: Chang Albert S. , Yannas Ioannis V. , Krarup Christian , Sethi Rajesh , Norregaard Thor V. , Zervas Nicholas T.
Published: March 2011

The rat sciatic nerve was transected mid-thigh and grafted with a silicone tube, the central 10 mm of which was filled with a collagen-glycosaminoglycan (CG) matrix. The rats were grafted contralaterally with empty silicone tubes as controls. The earliest compound muscle action potentials (CMAP's) at the plantar muscles were recorded around 11 weeks. After 30 weeks, the distal motor latencies recovered to about 50% higher than normal, the conduction velocity to about 50% normal, and the amplitudes of the CMAP's to about 50% normal. Of 7 rats in this study, all 7 nerves grafted with the CG matrix exhibited recovery, while only 1 grafted with the empty tube exhibited recovery. The CG matrix therefore appears to promote functional nerve regeneration across extended distances.
In-Vivo Screening of Platelet-Biomaterial Interactions in a Baboon Model
Authors: Yeager Anson A. , Hussein H. , Shoenfeld N. , Ramberg K. , Connolly R. , Callow A. D.
Published: March 2011

A percutaneous in-vig venous model was characterized by testing platelet deposition on standard vascular prosthetic materials in the baboon. The model detected significant difference in platelet deposition on ePTFE compared to Dacron. Low molecular weight dextran was administered following a baseline test period. A significant decrease in platelet depositionr occurred for both materials and coincided with a prolongation in bleeding time. No consistent decrease was found in control experiments which used no bolus or a saline bolus for treatment. Advantages of the model included ease of use and adaptability to test large numbers of materials. The model was suItable for in-vivo screening of platelet interactions with biomaterials placed in the bloodstream.