bluuebunny/crossref_metadata_2025 huggingface dataset:
Copper-Base Alloys Processed by Rapid Solidification and Ion Implantation
Authors: Wood J.V. , Elvidge C.J. , Johnson E. , Johansen A. , Sarholt-Kristensen L. , Henriksen O.
Published: March 2011

Alloys of Cu-Sn and Cu-B have been processed by both melt spinning and ion implantation. In some instances (eg Cu-Sn alloys) rapidly solidified ribbons have been subjected to further implantation. This paper describes the similarities and differences in structure of materials subjected to a dynamic and contained process. For example in Cu-B alloys (up to 2wt% Boron) extended solubility is found in implanted alloys which is not present to the same degree in rapidly solidified alloys of the same composition. Likewise the range and nature of the reversible martensitic transformation is different in both cases as examined by electron microscopy and differential scanning calorimetry.
Differences between Sputtering Methods in The Formation of Amorphous Magnetic Alloy Films
Authors: Hoshi Y. , Naoe M.
Published: March 2011

Fe-Si, Co-Ta and Co-Zr amorphous films have been deposited by using various sputtering methods (conventional rf diode sputtering, rf triode sputtering, dc Targets Facing type sputtering (dc TF sputtering) and dual ion beam sputtering (DIB sputtering)). The lower limit of the Si and Ta content to form amorphous Fe-Si and Co-Ta films changes significantly with the sputtering method. These differences between the sputtering methods are mainly caused by the differences in the plasma potential which affects the amount of ion bombardment to the film surface during sputtering,and the minimum content of Si or Ta to obtain amorphous films decreases as the plasma potential increases. These results indicate that the ion bombardment suppresses the growth of crystallites and promotes the formation of the films with amorphous structures. This is confirmed by the deposition of Co-Ta and Co-Zr amorphous films under the condition of various amount of ion bombardment by using a DIB sputtering system.
Leaching Studies of Crystalline Sodium Phases in Nuclear Waste Forms
Authors: Vance E.R. , Adl T.
Published: March 2011

The immobilization of non-radioactive Na in nuclear waste has not been given much attention. However since Na compounds are normally very soluble, Nabearing phases may render a waste form more susceptiible to leaching of radionuclides. The Na-phases may incorporate radionuclides and also, leaching of soluble Na phases will increase the surface area of the waste form. The crystalline Na-bearing phases which might occur in tailored ceramic formulations for nuclear waste are nepheline [1,2], magnetoplumbite [3] and sodalitetype materials [4]. Other Na phases which might occur in titanate-tailored [2,5] or titanate-encapsulated [6,7] forms are perovskite [8,9], Na2Ti3O7 (especially in titanate-encapsulated materials) and Na2TiSiO5 or Na2Ti2Si2O9, etc., if the waste contained sand or zeolites [10].
Solubility Effects in Waste Glass/Demineralized Water Systems
Authors: Fullam Harold T.
Published: March 2011

A study was carried out to determine the solubility limits of various elements found in waste glasses in demineralized water as a function of temperature. The work was sponsored by the Office of Nuclear Waste Isolation under contract to the Department of Energy. Solubility measurements were carried out at 35°, 65°, 95°, and 150°C using three nonradioactive waste glass compositions. Subsaturation and supersaturation methods were used to determine the solubility limits. The two methods gave markedly different values for most glass components. The results obtained indicate that it is difficult to assign solubility limits to most glass components without thoroughly describing the glass-water system. This includes not only defining the glass type, and system temperature, but also the glass surface area-to-water volume (S/V) ratio of the system and its thermal history.
Lanthanide Orthophosphates as a Matrix for Solidified Radioactive Defense and Reactor Wastes
Authors: Petek M. , Abraham M. M. , Boatner L. A.
Published: March 2011

Previous investigations have shown that the lanthanide orthophosphates (i.e., analogs of the mineral monazite) are promising candidate waste forms for the storage of high-level actinide or TRU wastes [1]. In the present work, the properties of lanthanide orthophosphates loaded with simulated Savannah River defense wastes and simulated reprocessed light water reactor wastes have been investigated with the goal of evaluating the potential of these materials as advanced primary waste forms.
Studies of Pollucite
Authors: Vance E.R. , Scheetz B.E. , Barnes M.W. , Bodnar B.J.
Published: March 2011

Pollucite (CsAlSi206) has been suggested [1,2] as a suitable phase for the incorporation and immobilization of 137Cs, on the basis of its refractory nature and leach resistance. The phase also occurs in tailored ceramic formulations designed for the disposal of commercial reprocessing waste [3,4] and zeolites which are heavily loaded with Cs [5,6].
Alpha Decay Self-Damage in Cubic and Monoclinic Zirconolite
Authors: Clinard F. W. , Land C. C. , Peterson D. E. , Rohr D. L. , Roof R. B.
Published: March 2011

Samples of primarily-monoclinic 238 Pu-doped zirconolite were stored at ambient temperature to allow accumulation of alpha decay self-damage to a dose of 6 × 1024 α/m3 (equivalent to a SYNROC age of ֮103 y). Bulk swelling reached 2.3 vol% with no tendency toward saturation, a damage response similar to that observed for cubic Pu-doped zirconolite. X-ray volumetric swelling at 4 × 1024 ֮/m3 was 1 vol%, considerably less than that for the cubic material. Changes in cell dimensions differed significantly from those reported by others for a monoclinic natural mineral. Extensive microcracking was observed, and is attributed at least partially to swelling differences between the matrix and minor phases.
Biological Intrusion of Low-Level Waste Trench Covers
Authors: Hakonson Thomas E. , Gladney Ernest S.
Published: March 2011

The long-term integrity of low-level waste shallow land burial sites is dependent on the interaction of physical, chemical, and biological factors that modify the waste containment system. Past research on low-level waste shallow land burial methods has emphasized physical (i.e., water infiltration, soil erosion) and chemical (radionuclide leaching) processes that can cause waste site failure and subsequent radionuclide transport.

The purpose of this paper is to demonstrate the need to consider biological processes as being potentially important in reducing the integrity of waste burial site cover treatments. Plants and animals not only can transport radionuclides to the ground surface via root systems and soil excavated from the cover profile by animal burrowing activities, but they modify physical and chemical processes within the cover profile by changing the water infiltration rates, soil erosion rates and chemical composition of the soil.

One approach to limiting biological intrusion through the waste cover is to apply a barrier within the profile to limit root and animal penetration with depth. Experiments in the Los Alamos Experimental Engineered Test Facility were initiated to develop and evaluate biological barriers that are effective in minimizing intrusion into waste trenches. The experiments that are described employ four different candidate barrier materials of geologic origin. Experimental variables that will be evaluated, in addition to barrier type, are barrier depth and soil overburden depth. The rate of biological intrusion through the various barrier materials is being evaluated through the use of activatable stable tracers.
Hot-Pressed Barium Sulphate Ceramic Waste Forms for Direct Immobilisation of Medium Level Magnox Waste
Authors: Briggs A. , Jones D.V.C. , Cole G.B.
Published: March 2011

A possible method of treatment for Magnox cladding waste is by dissolution in nitric acid and precipitation of barium sulphate-based floc with which radioactive ions are co-precipitated. The floc could then be immobilised in a matrix material such as cement or bitumen to give the waste form, or alternatively can be converted directly into a waste form by hot pressing.

This paper describes the direct conversion of barium sulphate floc, containing simulated radwaste, into a synthetic, ceramic version of the natural mineral barite by a hot-pressing route. By variation of the parameters pressure, temperature and time, optimum conditions for consolidation of the floc to > 90% theoretical density on a laboratory scale are found to be 22.5 MPa, 900°C for 10 minutes. Using a pressure of 15 MPa, at 900°C for 30 min., hot-pressed billets of BaSO4 have been made on a 5 kg scale. In going from the Magnox waste to the hot-pressed barium sulphate a volume reduction factor ∼ 18 is achieved. The principal phases in the product are found to be BaSO4 , MgO and Fe3O4, and the degree of consolidation achieved depends on the MgO content.

The leaching behaviour of the hot-pressed materials in 100°C, 3 day Soxhlet tests also depends on the MgO content, and on the consequent level of open porosity. If there is porosity accessible to the leach water, MgO at the internal surfaces is converted to Mg(OH)2, which deposits within the pores, and a weight gain is registered in the Soxhlet test. If, however, there is no open porosity, a weight loss occurs, and leach rates ∼ 4 × 10−7 kg/m2/sec are found. In contrast, pure BaSO4, hot-pressed to similar densities, shows no variation in leaching behaviour over a wide range of o en porosities, and gives Soxhlet leach rates ∼ 8 × 10−8 kg/m2/sec.
The Application of 57FE Mössbauer Spectroscopy to the Characterization of Nuclear Waste Forms
Authors: Huray Paul G. , Spaar M. T. , Nave S. E. , Legan J. M. , Boatner L. A. , Abraham M. M.
Published: March 2011

The electronic charge states and site symmetries of the radioactive ions incorporated in nuclear waste forms are of considerable importance in determining the physical and chemical properties of these materials. An in situ characterization of these ions is, unfortunately, often difficult – especially when a mixture of charge states and local crystal symmetries exist. The application of Mbssbauer spectroscopy represents a powerful technique for obtaining solid state chemical information.
Application of Ion Beam Techniques to the Study of Glass Durability: Enhanced Dissolution in Saline and Radiation Effects
Authors: Burman C. , Ke-Ming Wang , Lanford W.A.
Published: March 2011

Nuclear reaction analysis, Rutherford backscattering and ion implantation techniques are applied to the study of the reaction between glass and aqueous solutions. The use of these techniques is described as are some of the results obtained. Solutions of NaCl are seen to etch some glasses several orders of magnitude faster than distilled water. Radiation damage created by high energy heavy ion bombardment is seen to have great effects on the penetration of hydrogen (water) into glass.
Point Defects and Microstructural Stability of Glasses Under Irradiation
Authors: Antonini Marcello , Buckley Samuel N. , Camagni Paolo , Gibson Peter N. , Manara Adriano
Published: March 2011

The results of previous optical absorption experiments aiming to investigate the behaviour of atomic defects in silica based glasses irradiated with various types of particles have been extended to examine the effects of multiple irradiations which take place during long term storage of glasses containing HLW. In addition, point defect clustering phenomena have been investigated by means of high voltage transmission electron microscopy. It has been found that due to the large number of defects already present in amorphous silica prior to irradiations, the contributions of different bombarding particles to the total damage cannot be considered fully additive in terms of the relative number of displaced atoms, but some consideration has to be made of defect interactions and ionization damage. Clustering effects, while being absent in pure silica, are present in borosilicates at large dose rates (≳1022 electrons m−2 sec−1 ). At lower beam current densities and doses comparable to those achieved after 10–100 years of HLW storage, phase separation into a microcrystalline compound has been detected by transmission electron microscopy.
Radiation Effects in Radwaste Glasses : A Reappraisal of Alpha-Recoil Aging as Simulated by Ion Implantation.
Authors: Dran J.C. , Langevin Y. , Maurette M. , Petit J.C.
Published: March 2011

New results on the etchability of lead implanted silicate glasses are presented which are satisfactorily accounted for by a Monte Carlo Model of etching. These results strongly support the radiation damage origin of the ion-induced modification of the chemical reactivity of glass. Major artefacts of ion implantation are then discarded as possible causes of the observed effects and consequently this technique is shown to be a valuable tool for the study of α-recoil aging in H.L.W. glasses.
Immobilization of High Level Nuclear Reactor Wastes in Synroc: A Current Appraisal
Authors: Oversby V.M. , Ringwood A.E.
Published: March 2011

Results are presented for leach testing at 95°C and 200°C of SYNROC containing 9% and 20% simulated high level radioactive waste, synthetic hollandite and pervoskite samples, and natural zirconolite and pervoskite samples. Single phase synthetic minerals show much higher leach rates than natural mineral samples and polyphase SYNROC samples. Natural zirconolite samples with low radiation damage have leach rates at 200°C based on U which are identical to those measured on SYNROC samples. Natural zirconolites with very large accumulated α dose and radiation damage have leach rates at 200°C which are only 5 times higher than those of low dose samples.
Rutherford Backscattering Investigation of the Corrosion of Borosilicate Glass
Authors: Sales B. C. , Boatner L. A. , Naramoto H. , White C. W.
Published: March 2011

One of the major reservations regarding the use of glass as a primary nuclear waste form is its ability to retain hazardous radioactive nuclei when exposed to ground water at tenmeratures above about 75C. It is now generally accepted that the removal of radioactive nuclei from glass in an aqueous environment proceeds via two main mechanisms, i.e., either by a diffusion process (which may be driven or undriven) or by direct matrix dissolution - which, in its initial phase, also results from a diffusion related process [1]. The term "leaching" is generally employed in describing the overall process resulting in the removal of nuclei (whether they are radioactive or not) from glass that is exposed to an aqueous environment.
Structural Groupings in Borate Glasses
Authors: Bray Philip J.
Published: March 2011

A. A. Lebedev developed a crystallite model for glasses in the 1920's which was supported by the 1930 publication of Randall, Rooksby, and Cooper But, the 1932 publication by Zachariasen entitled “The Atomic Arrangement in Glass” introduced the Warren and Zachariasen continuous random network (CRN) model. In that model, as applied to oxide glasses, oxygen polyhedra surrounding cations (e.g. SiO4 tetrahedra in silicate glasses) are linked together in a random manner to form extensive three-dimensional networks which do not exhibit long-range symmetry or periodicity. Zachariasen did assume that the forces between atoms in glasses and crystals are essentially the same, and noted the same polyhedra in both, but did not discuss any further possible correspondence between glasses and crystals.
Ultraviolet Irradiation Induced Compaction and Photoetching in Amorphous, Thermal SiO2
Authors: Fiori C. , Devine R. A. B.
Published: March 2011

Laser irradiation (λ = 248 nm, E = 5 eV) of thermal, amorphous SiO2 is found to produce thermally reversible, linear compaction reaching a maximum of 16 % (accumulated, incident dose of ∼ 2000 J/cm2 followed by irreversible compaction and photoetching. Assuming the volume fluctuation to be ΔV/V = 3(Δ1/1)/(1+2σ) this corresponds to a maximum volume fluctuation of −36 %. An approximately linear refractive index versus ΔV/V relationship found in the linear compaction regime agrees with the predictions of the Lorentz-Lorenz law. Laser compaction results are found to be consistent with those obtained using hydrostatic pressure. That is argued by comparison with crystalline SiO2 polymporph, that compaction occurs via collapse of a high order ring structure into one having predominately 2 or 3 membered rings. Irreversible compaction/etching occurs when the lattice can no longer support a reduction in ring dimension and dangling bond defects are created. The presence of a large number of defects is sufficient for mechanism of superficial desorption and photoetching to become important.
The Electronic Structure of Doped Arsenic Triselenide
Authors: Barclay R. P. , Marshall J. M. , Main C.
Published: March 2011

We have investigated the electronic properties of films of arsenic triselenide into which the transition metal nickel has been introduced by a co-sputtering technique. Measurement of d.c. conductivity, thermopower, optical absorption and photomobility have been performed to characterise the material. These measurements give new information concerning the influence of nickel on the optical gap, the position of the Fermi-level, and other aspects of transport in As2 Se3. In the most heavily doped sample the d.c. conductivity is increased by 11 orders of magnitude and the position of the Fermi-level is shifted by ΔEF∼0.6 eV. The results are explained in terms of a model in which an acceptor level is introduced into the valence band tail of a background density of states (DOS) obtained earlier for the undoped material. In contrast to the suggestion by previous workers that the incorporation of high concentrations of nickel can produce a transition to n-type conduction, we argue that the Fermi-level remains in the valence band tail and that hopping conduction of carriers close the Fermi-level yields a negative sign in thermopower.
Influence of Quenched Defects on Thermal Expansion and Glass Transition in Diopside (CaMgSi2O6)
Authors: Raman S. V.
Published: March 2011

This study was conducted to investigate the possible occurrence of non-equilibrium defects and their influence on glass transition in a relatively depolymerized silicate structure. The glass of interest has an average bridging/non-bridging oxygen ratio of 1:2. It was prepared by fast quenching and was examined in the alumina pushrod dilatometer at heating rates of 5 and 15 ° C/min. The thermal expansion decreases with increase in the rate of heating although, the expansion coefficient is independent of heating rate at temperatures below the transition region. In the supercooled liquid region the expansion coefficient is higher at the higher heating rate. In the transition region it is both heating rate and temperature dependent. Three distinct temperatures are revealed in the transition region from temperature dependence of expansion rate. Their dependence on heating rate is described by a low activation energy of about 3Kcal/mol for transition. The single parameter fictive temperature is not in agreement with kinetics of relaxation due to a wide temperature interval of 600 to 750° C for the transition region. The transition kinetics is perhaps enhanced by the presence of defects whose annealing is impedded with increase in heating rate. Thus under the influence of higher defect concentration a spiked change in relaxation rate occurs and points to the presence of a critical temperature in the transition region. In the neighborhood of this temperature the relaxation rate of supercooled liquid is significantly lower than its solid analog. For short relaxation times in the supercooled liquid thermal expansion coefficient is relatively higher at the higher heating rate.
Liquid Chromatography and Raman Scattering Spectroscopy Measurements of Lead-Iron Phosphate Glasses
Authors: Sales B. C. , Ramsey R. S. , Bates J. B. , Boatner L. A.
Published: March 2011

Due to the limited amount of structural information that can be obtained using traditional techniques of solid state physics (e.g., x-ray or neutron diffraction), the structure of oxide glasses has remained a controversial topic since the introduction of the “random network theory” in 1932. While there are several experimental methods that can provide detailed information about the local structural properties of glasses (e.g., NMR, EXAFS, optical absorption, Mössbauer absorption, and EPR spectroscopy), very little information is available regarding the distribution of intermediate size (∼10–500 Å) structural units.
Elastic Properties of Glasses
Authors: Thorpe M. F.
Published: March 2011

It is shown that the elastic properties of covalent networks are very sensitive to coordination. High coordination networks are relatively hard and the elastic constants are determined by the covalent forces. Low coordination networks are relatively soft and the elastic constants are determined by longer range forces.
Theoretical Study of Semiconductor Interfaces
Authors: Walle Chris G. Van De , Martin Richard M.
Published: March 2011

We perform self-consistent density functional calculations on semiconductor heterojunctions, using ab initio nonlocal pseudopotentials, and derive valence band discontinuities for many different lattice matched interfaces. Spin-orbit effects are included a posteriori. A comparison is made with previous calculations, which used empirical pseudopotentials, and with other heterojunction theories. We find reasonable agreement with reported experimental values, and derive some important conclusions about the nature of the lineups.
The Stony brook Multiprocessing Materials Simulator
Authors: Carleton Herbert R.
Published: March 2011

A parallel processing system with substantial computational power for the simulation of materials has been designed and constructed at Stony Brook. Although primarily designed to implement the molecular dynamics algorithm, the system is highly efficient in carrying out simulations that exhibit high degrees of local interaction. Our studies show that this system is capable of performance, for this application, which is comparable to the Cray-l at a small fraction of the cost.
Modelling of Thin Film Grain Structures and Grain Growth
Authors: Frost H. J. , Thompson C. V.
Published: March 2011

We have generated two-dimensional grain structures by considering constant growth of regions which nucleate under various conditions. We have considered continuous nucleation at a constant rate, nucleation site saturation, continuous nucleation with nucleation-exclusion zones surrounding the growing regions, and decaying nucleation rates. The microstructures resulting from these varying conditions differ markedly in their topological and geometric properties.

We have also developed a program which models grain boundary motion in structures resulting from nucleation and growth. Results from these models will be compared to observed microstructures in thin metallic and semiconductor films and should provide insight into the mechanisms of microstructural evolution and control.
Microscopic Phenomena of Macroscopic Conseouences:Interfaces, Glasses, and Small Aggregates
Authors: Landman Uzi , Barnett R. N. , Cleveland C. L. , Luedtke W. D. , Ribarsky M. W. , Scharf Dafna , Jortner Joshua
Published: March 2011

Computer simulations open new avenues in investigations of complex material systems and phenomena. The methodology, development and applications of molecular dynamics simulations are discussed and the wealth of microscopic information revealed via simulations of interphase-interfaces, liquid metals, metallic glasses and small aggregates are demonstrated.
The Solid-Liquid Interface: Theory and Computer Simulations
Authors: Laird B. B. , Haymet A. D. J.
Published: March 2011

We present the results of computer simulations of body centered cubic (bcc)/melt interfaces, with particular emphasis on the “width” of the interface. Both static and dynamic properties of single crystal/liquid interfaces are examined. The implications for crystal growth near equilibrium are discussed. The results of these computer “experiments” are compared with an extended density functional theory of the solid-liquid interface.
From Hamiltonians to Phase Diagrams
Authors: Hafner Jūrgen
Published: March 2011

The ab-initio calculation of phase diagrams for metals and alloys using electronic and thermodynamic perturbation theories is discussed.
High Sensitivity Auger Spectroscopy
Authors: Larson L. A.
Published: March 2011

The technique of Auger Electron Spectroscopy has been investigated for the purposes of detecting contamination levels in high dose ion implants. Historically, Auger sensitivities have been considered to be on the order of 1%. This is due to the rather large secondary electron background and the various combinations of electron beam and detector noise that may occur. In this study, it is shown that the use of background subtraction and integration of the resulting EN(E) Auger peak will result in considerably better sensitivities for the case of ion implants in silicon.
Sem-Based Characterization Techniques
Authors: Russell Phillip E.
Published: March 2011

The scanning electron microscope is now a common instrument in materials characterization laboratories. The basic role of the SEM as a topographic imaging system has steadily been expanding to include a wide variety of SEM-based analytical techniques. These techniques cover the range of basic semiconductor materials characterization to live-time device characterization of operating LSI or VLSI devices. This paper will introduce many of the more commonly used techniques, describe the modifications or additions to a conventional SEM required to utilize the techniques, and give examples of the use of such techniques. First, the types of signals available from a sample being irradiated by an electron beam will be reviewed. Then, where applicable, the type of spectroscopy or microscopy which has evolved to utilize the various signal types will be described. This will be followed by specific examples of the use of such techniques to solve problems related to semiconductor technology. Techniques to be emphasized will include: x-ray fluorescence spectroscopy, electron beam induced current (EBIC), stroboscopic voltage analysis, cathodoluminescence and electron beam IC metrology. Current and future trends of some of these techniques, as related to the semiconductor industry, will be discussed.
Sem-Ebic Characterization of Semiconducting and Semi-Insulating LEC-GaAs
Authors: Tokumaru Yozo , Okada Yasumasa
Published: March 2011

We have applied the SEM-EBIC technique (electron-beam-induced current method using a scanning electron microscope) to the characterization of both semiconducting and semi-insulating liquid encapsulated Czocralski (LEC) grown GaAs and have found this technique to be effective for semiinsulating materials as well as semiconducting ones. In semiconducting Si-, In- and undoped LEC-GaAs, growth striations were observed under usual measurement conditions. In semi-insulating undoped LEC-GaAs, clear EBIC images of individual dislocations and cell structures of dislocations were obtained by applying a high reverse bias voltage of about 10∼100 V to the specimens. We have also investigated nearly dislocation-free semiinsulating In-doped LEC-GaAs and found inhomogeneities which are different from those observed in undoped specimens. The spatial resolution of this technique is estimated to be 2–3 μm, which agrees with the experimental result
Characterization of Thin Film Dielectrics by FTIRS
Authors: Cox J. Neal
Published: March 2011

The silicon-oxygen chemical bond is the key building block for many of the dielectric thin films used in silicon MOS technology. High quality thermal silicon oxides serve as gate dieletrics. CVD silicon oxides, produced by a variety of deposition processes, are used as interlayer dielectrics and as passivating layers. These films may be stoichiometric or nonstoichiometric, or doped with boron and/or phosphorus to provide the most desirable film properties.

Bandshape analysis of the Fourier Transform Infrared (FTIR) spectra of these films can provide information on the chemical bond strength, the homogeneity, and the optical dielectric function of various glasses. Spectral features are found to change characteristically, depending upon deposition conditions, subsequent processing (densification), the influence of dopants, stress, and the effects of overlying films. In comparing films [Bposited under different conditions, the primary Si-O stretching mode peak position shifts over a 30cm-1 range and has a FWHM that varies by as much as 50%. The FTIR technique can routinely resolve peak shifts in glasses as small as 2 cm-1, sufficient to detect the differences observed due to deposition or processing.
Micro-Reflection Spectroscopy Profiling of Interdiffusion in Epitaxial HgCdTe
Authors: Grimbergen M. , Szilagy A.
Published: March 2011

Composition profiles of interdiffused epitaxial Hg1-xCdxTe have been determined using interband E1 microreflection spectroscopy. The technique provides a rapid, noncontacting method of compositional analysis using the near UV-visible spectral range. It measures alloy composition (x-value) over a sampling surface as small as 5 μm square to an accuracy better than 0.01. Profiles are measured by repeatedly etching small sampling wells in discrete steps. Profiles were measured on epitaxial Hg0.7Cd0.3Te films grown on Hg0.8Cd0.2Te substrates with and without extended anneal treatments. They were also calculated by numerically solving the diffusion equation using published composition dependent diffusion coefficients. The experimental and theoretical profiles are compared graphically. Calculated as-grown and annealed interdiffusion widths (9 and 13μm, respectively) differ from measured values by less than 15%. It is shown that Hg and Cd interdiffusion during both the growth and subsequent anneal is responsible for the observed interface widths.
Quantitative Materials Analysis by Laser Microprobe Mass Analysis
Authors: Odom Robert W. , Hitzman Charles J. , Schueler Bruno W.
Published: March 2011

The laser microprobe mass analysis (LMMA) technique currently finds extensive application in the qualitative microanalysis of a wide range of materials. These microanalytical applications include the analysis of polymeric materials [1], semiconductors [2] and particulate samples [3]. These qualitative analyses have repeatedly demonstrated the analytical ability of this technique for producing rapid, elemental, isotopic and, in some cases, molecular characterization of these types of materials. The development of quantitative or semi-quantitative analytical methodologies is the goal of any analytical technique and rather extensive investigation of the quantitative capabilities of the laser microprobe technique have been pursued since the initial development of this technique. These investigations have centered on developing appropriate microanalytical standards [4], characterizing the pertinent physical and chemical processes occurring during high power laser irradiation of materials [5] and modeling the nature and extent of the ionization produced with physically reasonable models [6, 7]. To date, these quantitative studies have generally provided good analytical methods and results and, although the number of quantitative analyses of materials systems have been rather limited, the results do provide sufficient encouragement to pursue further quantitative studies with this technique. In this paper, we discuss the results obtained in a laser microprobe analysis of phosphosilicate glass (PSG) standards in which the quantitative capabilities of the technique for the determination of the phosphorous content of PSG glasses were evaluated. The results of this analysis were compared to those produced from a secondary ion mass spectrometry (SIMS) analysis of these PSG standards. We have also evaluated the in-depth profiling capability of the laser microprobe technique and demonstrate this capability with a depth profile of a 11B implant into Si. Finally, we present preliminary data obtained from a new modification to the basic laser microprobe technique in which the conventional laser system is employed to ablate the sample material and a second laser pulse ionizes the neutral-components in the vapor plume produced by the ablation laser. This two laser configuration of the laser microprobe promises to improve the sensitivity and reproducibility of this microanalysis technique.
Present and Emerging Techniques for Materials Microanalysis
Authors: Helms C. R.
Published: March 2011

Although classical materials characterization methods have existed for many years, modern microanalytical techniques had their start just over twenty years ago. In this paper, I will discuss some of the common techniques available today including AES, XPS, or ESCA, RBS, SIMS, and EDAX. A comparison of the key capabilities and limitations will be given including sensitivity, spatial resolution, quantitative analysis, nondestructive testing, chemical state determination, and analysis speed. It is clear that the reason each of these techniques still exists as commercial instrumentation is that each provides a unique set of capabilities, but also a unique set of limitations. To become viable in the materials analysis arena, a new technique must offer a significant extension of the capabilities already available but not at the cost of too severe a set of limitations. Examples would be the development of tools that offer both high sensitivity with accurate quantitative analysis, or good spatial resolution with high sensitivity, or minimal damage but good spatial resolution, etc. A number of papers in this volume will describe the details of these emerging technologies which provide advances in these areas; and I will attempt here to put a number of these new developments in perspective with regard to the more commonplace techniques available.
The Depth Resolution of Dynamic Sims: Experiments and Calculations
Authors: Giles M. D. , Hoyt J. L. , Gibbons J. F.
Published: March 2011

This study is concerned with the fundamental limitations imposed by cascade mixing and recoil implantation on the depth resolution of secondary ion mass spectrometry (SIMS), and the effects of these limitations on the determination of impurity profiles in semiconductors.

We present experimental results of measurements on atomically, or near atomically abrupt impurity profiles in Si using magnetic sector (Cameca) and quadrupole (Atomica) SIMS machines. The analysis conditions and samples have been chosen to minimize instrument (crater wall resputtering) and surface (equilibration time) effects. Under such conditions the leading edge of an abrupt signal is smeared to a complimentary error function, while the trailing edge exhibits an exponential decay reminiscent of recoil implantation profiles.

Modifications of the Boltzmann Transport Equation (BTE) approach to ion implantation in multilayer targets will be shown to provide a first principles calculation of such SIMS knock-on phenomena, which is in good agreement with the empirical results.
Using Hyperfine Interaction for the Structural Characterization of Amorphous Silicon
Authors: Stutzmann Martin , Biegelsen David K.
Published: March 2011

The hyperfine interaction between electronic and nuclear spins in hydrogenated amorphous silicon has been observed for the various paramagnetic defects in this material by electron spin resonance (ESR) and electron nuclear double resonance (ENDOR). The large hyperfine interaction between dangling bonds and 29Si as well as between donor electrons and 31p or 75 As nuclei can be resolved in ESR and provides direct information about the structure of the underlying electronic states. The smaller dipolar coupling of all paramagnetic states to more distant nuclei leads to an ENDOR response near the free nuclear resonance frequencies, which can be used to study the coupling of the electronic and nuclear spin system to the lattice phonons and to each other.
Formation of Au-Si Metastable Phases by Ion Mixing
Authors: Liu Bai-Xin , Wieluniski Leszek S. , MÄenpÄÄ Martti , Nicolet Marc-A. , Lau S. S.
Published: March 2011

Amorphous and three metastable crystalline phases have been formed in the Au-Si system by 300 keV Xe ion mixing using multilayered samples with average compositions of Au2Si8, AuSi, and Au7 Si3. Generally speaking, during the different stages of irradiation at liquid nitrogen temperature (LNT) or room temperature (R.T.), metastable crystalline phases are formed initially, and eventually an amorphous structure is obtained. Thermal decomposition of amorphous alloys yield different metastable crystalline phases. Some of the metastable crystalline phases can be formed directly from multilayered samples by steady-state thermal annealing. The formation mechanisms of metastable phases are discussed in terms of the processes involved in ion mixing and thermal annealing.
Atomic and Electronic Structure of Amorphous Alloys
Authors: Johnson William L.
Published: March 2011

Amorphous metallic alloys can be synthesized by many techniques including melt quenching, vapor quenching, electrodeposition, and irradiation of crystalline alloys by neutrons or by ions. Certain alloys are prone to glass formation and can be readily made amorphous by all of these methods. In this article, a survey of experimental data on the atomic and electronic structure of such good glass forming alloys is presented. On the basis of this data, it is argued that good glass forming alloys tend to have in common several underlying microscopic features. The article concludes with some general remarks on the relationship of these common features to glass formation.
Non Equilibrium Structures in Ion Implanted B2 Type Fe-Al and NiTi Ordered Alloys.
Authors: Moine P. , Riviere J. P. , Junqua N. , Delafond J.
Published: March 2011

Two b.c.c. ordered alloys Fe-40 at % Al and Ni-Ti have been investigated by transmission electron microscopy after self ion implantation Al+ and Ni+ respectively. Partially disordered regions are observed in the Fe-40 at % Al. On the contrary, in the Ni-Ti alloy, complete transformation to the amorphous state occured. During post implantation annealings, the precipitation of a new f.c.c. phase is observed in the Fe-40 at % Al ordered alloy, in the amorphous Ni-Ti the recrystallization occurs in a temperature range 400 – 550°C; the new phase has a structure either martensite type or B2 type with modulatiens.
Friction and Wear of Stainless Steels Implanted with Ti and C
Authors: Yost F. G. , Pope L. E. , Follstaedt D. M. , Knapp J. A. , Picraux S. T.
Published: March 2011

Friction and wear tests were completed on Fe, and stainless steels of the type 304, 15–5 PH, Nitronic 60 and 440C implanted with Ti and C. Samples were mechanically polished prior to ion implantation to fluences of 2 × 1017 Ti/cm2 (90–180 keV) and 2 × 1017 C/cm2 (30 keV); the implantation profiles of the two elements overlapped to 0.1 μm. Light load wear conditions with no lubrication were evaluated in a pin-on-disc configuration. Ion implantation significantly reduced the friction coefficient by up to 75% and decreased the maximum wear depth by up to 95%, but both effects were material and load dependent. Only stainless steel 304 had both friction and wear reduced by implantation for all loads examined. Fine-scale parallel grooves were present in the wear track for light loads, but this wear pattern was transformed to a galled structure at high loads. A correlation existed between decreased friction, reduced wear, the wear track morphology and Ti in the wear track.
Structure and Properties of Silicon Carbide Implanted With Chromium
Authors: Mchargue C. J. , Williams J. M.
Published: March 2011

The effects of implanting chromium at fluences of up to 2.6 × 1016/cm2 on the structure and properties of single- and polycrystalline samples of SiC were studied. The material turned amorphous due to the implantation. The hardness decreased by as much as 25% and the fracture toughness increased by approximately 10% due to the implantation. The most interesting finding was that the material swells by as much as 30% upon implantation of some 2 × 1016 Cr-ions/cm2.
Thermal Stability of Metastable Phases Produced by Laser Treatment of Aluminium Implanted With Chromium and Molybdenum
Authors: Battaglin G. , Carnera A. , Della Mea G. , Mazzoldi P. , Jain Animesh K. , Kulkarni V.N. , Sood D.K.
Published: March 2011

We present a first He ion channeling study on thermal stability (under isochronal vacuum furnace annealing at 300-650°C) of metastable solid solution phases produced by pulsed ruby laser treatment of Al implanted with Cr and Mo. Laser treated Cr exhibits strong redistribution inferred to be due to intermetallic phase precipitation which appears to be enhanced by quenched-in defects. In contrast, laser treated Mo shows no redistribution but only a loss of substitutionality. Instead of annealing, thermal treatment produces an increase in host dechanneling yield for all laser treated samples. Detailed comparison with thermal recovery of as implanted phases demonstrates the key role played by quenched-in defects.
Raman Spectra of Ion Implanted Graphite
Authors: Elman B.S. , Mazurek H. , Dresselhaus M.S. , Dresselhaus G.
Published: March 2011

Raman spectroscopy is used in a variety of ways to monitor different aspects of the lattice damage caused by ion implantation into graphite. Particular attention is given to the use of Raman spectroscopy to monitor the restoration of lattice order by the annealing process, which depends critically on the annealing temperature and on the extent of the original lattice damage. At low fluences the highly disordered region is localized in the implanted region and relatively low annealing temperatures are required, compared with the implantation at high fluences where the highly disordered region extends all the way to the surface. At high fluences, annealing temperatures comparable to those required for the graphitization of carbons are necessary to fully restore lattice order.
Ion Mixing During Film Deposition: Growth of Metastable Semiconducting and Metallic Alloys
Authors: Cadien K.C. , Ray M.A. , Shin S.M. , Rigsbee J.M. , Barnett S.A. , Greene J.E.
Published: March 2011

Epitaxial metastable (GaSb)1−Gex alloys with compositions across the pseudobinary phase diagram have been grown on (100) GaAs substrates by multitarget rf sputtering. An essential feature allowing the growth of these unique materials was low energy ion bombardment of the growing film during deposition to promote collisional mixing and enhance adatom diffusion. Annealing experiments indicated that the metastable films exhibit good high temperature stability. While the free energy difference between the single phase metastable and two phase equilibrium states is only ∼ 20 meV/atom, the activation barrier for the transformation is ∼ 3 eV. All films were ptype with room temperature carrier concentrations and mobilities between 1016 and 1019 cm−3 and 10 and 720 cm2/V∼sec, respectively, depending on film composition. Collisional mixing due to low energy ion bombardment of the growing film was also found to affect both the transformation rate kinetics as well as the reaction path during subsequent annealing of amorphous GaSb/Ge mixtures deposited on glass at 60°C. Finally, some initial results on the deposition of metastable fcc Cu/Cr alloys are presented.
Influence of Preparation Conditions on Charge Carrier Dynamics In a-Si:H Determined By An In-Siju Technique
Authors: Werner A. , Kunst M.
Published: March 2011

Contactless photoconductivity measurements with the time-resolved microwave conductivity technique have been performed during the growth of hydrogenated amorphous silicon films. it has been shown that low substrate temperature and thin films lead to a larger electron decay rate and to an increased infrared absorption compared with high quality films. Addition of H2S to SiH4 during the glow discharge process leads to a worse fi1m quality which can be detected in-situ.
Interpretation of The a-Si:H DLTS and ICTS Experimental Data
Authors: Han Ru-Qi , Ngai K. L. , Ruvalds J.
Published: March 2011

The isothermal capacitance transient spectroscopy (ICTS) data of a- Si:H is consistently analyzed in terms of a relaxation function with a fractional exponential time decay of the form φ(t)=exp[-(t/τ*)λ] with λ≅0.8. The anomalous variation of the effective relaxation time τ* (and hence that of the attempt-to-escape frequency ν* and the capture cross section σ* observed by Okushi and coworkers) with energy and temperature is shown to follow an additional prediction of the time dependent relaxation rate coupling model developed by Ngai and coworkers for relaxations in many complex systems. A modified energy scale is extended from the ICTS analysis which brings its electronic density of states structure in closer agreement with results obtained by DLTS experiments.
Deposition Kinetics and Structural Control of Highly Photosensitive A-SiGe:H Alloys
Authors: Tanaka Kazunobu , Matsuda Akihisa
Published: March 2011

Firstly, on the basis of the classical model on the surface process of adsorbed species, a guiding principle is proposed for the preparation of high-quality a-SiGe:H alloys via plasma-CVD technique. Secondly, a- SiGe:H alloys were prepared by the rf-discharge technique with three intentional modifications; (A) from SiH4/GeH4 using a diode reactor (conventional method), (B) from SiH4/GeH4 using a triode reactor (triode method), (C) from SiH4/GeH4/H2 mixture using the diode reactor (H2-dilution method). Finally, growth mechanism is discussed in terms of the selection of long-lifetime radicals in a plasma and the H-coverage factor of the growing surface, providing us a clue to materials design.
Infrared Spectroscopy of Deuterated a-Si, Ge:D, F Alloys Prepared by DC Glow Discharge Deposition
Authors: Okada Y. , Slobodin D. , Chou S. F. , Schwarz R. , Wagner S.
Published: March 2011

Deuterated and fluorinated amorphous silicon-germanium alloys, a-Si, Ge:D, F, were studied by Fourier transform infrared (IR) spectroscopy. No Ge.-F modes are observed. The intensity of the Si-F and Si-F2 modes increases with Ge concentration. So does thae intensity of SiF4 which is trapped as isolated molecules. No DF (IR) or F2 (Raman) is observed. The IR spectra of alloys annealed at 300, 400, 500 and 600° C show that the fluorine in the Si-F and Si-F2 groups and in the SiF4 molecules is in thermochemical equilibrium.
Surface Reactions in Discharge and Cvd Deposition of Silane
Authors: Gallagher Alan
Published: March 2011

Glow discharge deposition of hydrogenated amorphous silicon films involves; (A) the electron collisions which produce the reactive species, (B) the gas reactions these species undergo while diffusing or drifting to the surfaces, and (C) the surface reactions involved in film growth and gas processing. I will first describe our knowledge of the electron and gas reactions in these discharges, then of the surface reactions, and finally I will offer some conjectures regarding the influence of these different surface reactions and bombardments upon film properties.
Glow Discharge Produce Amorphous Sic:H Thin Films
Authors: Tran N. T. , Olsen D. J. , Patel R. I. , Epstein K. A.
Published: March 2011

Amorphous hydrogenated silicon carbide alloy films (a-SiC:H) were produced by the decomposition of methane and silane in a glow discharge deposition system. A deposition rate of 13 Å/sec was achieved for good quality films. Amorphous SiC:H films of p+type and n+type of a band gap of 1.86 eV and 1.8 eV and the activation energy of 0.4 eV and 0.23 eV, respectively were obtained. Results show that p+type and n+type a-SiC:H films can be good window layers and good diffusion barriers for indium in polyimide/metal/n-i-p(p-i-n)/ITO amorphous silicon solar cells.
The photosensitivity of a-Si:H/P+Pc-Si heterojunction
Authors: Wang Wanlu , Liao Kejun
Published: March 2011

We have investigated the photosensitivity of the a-Si:H/P+Pc-Si heterojunction. It has been found that the capacitance of a-Si:H/P+Pc-Si heterojunction have an excellent photosensitivity, and potential application as a photosensitive capacitors.