bluuebunny/crossref_metadata_2025 huggingface dataset:
Grain Boundary Structure and Morphology in 30° <100> Tricrystal Films of Al
Authors: Thangaraj N. , Dahmen U.
Published: March 2011

The structure and morphology of 30° <100> tilt grain boundaries in tricrystal films of Al have been investigated by conventional and high resolution electron microscopy. By inducing heteroepitaxial growth on single crystal (111) Si substrates, Al formed polycrystalline thin films made of grains in three symmetry-related (100) orientations. The grain boundaries were well-faceted and a number of symmetric and asymmetric tilt boundaries and triple junctions were observed. Their morphology, topology and preferred faceting was related to the 12mm two-dimensional point symmetry of the tricrystal.
Study of Thermal Oxide Solid-State Reaction on GaAs Surfaces
Authors: Lu Z. , Chen D. , Osgood R. M. , Podlesnik D. V.
Published: March 2011

In this paper, we will present a study of the thermal reaction of AsjOs with GaAs at temperatures below 550°C using monochromatic X-ray photoelectron spectroscopy (MXPS). A solid-state interface reaction of 4GaAs + 3AS2O5 → 2Ga2O3 + 3AS2O3 + 4As, which includes the usual native oxide thermal reaction: 2GaAs + AS2O3 → Ga2O3 + 4As, as well as a decomposition reaction AS2O5 → AS2O3 + O2 is responsible for the thermal reaction in this temperature range.
Phase Formation at Pd/Si1−xGex Interfaces
Authors: Buxbaum A. , Eizenberg M. , Raizman A. , Schäffler F.
Published: March 2011

In this work we describe the interaction of Pd with Si1−xGex layers in terms of structure, composition and electrical properties. Strained epitaxial layers of Si1−xGex with x=0.09 and 0.18 were grown on Si (100) by Molecular Beam Epitaxy (MBE) at a growth temperature of 550°C, to a thickness of 3300Å and 2300Å, respectively, and then capped with a 100Å Si layer. At low temperatures (around 250°C), the formation of a ternary phase Pd2Si1−xGex along with small amounts of PdGe takes place. At high temperatures (around 550°C), the interaction is characterized by the formation of a double layered structure, where a Ge rich Si1−xGex region is formed between the Pd2Si1−xGex compound and the unreacted Si1−xGex. The high temperature treatment results in strain relaxation in the epilayer below the compound region. Electrical characterization of diodes formed from these layers clearly shows they are rectifying, with Schottky barrier heights around 0.65 eV.
Description of the Atomic Positions Around Interfacial Ledges in Terms of the Somigliana Dislocation Model
Authors: Bonnet R. , Loubradou M.
Published: March 2011

In many materials, crystalline interfaces are facetted. The experimental evidence is that on each side of an interfacial ledge, or along the facets meeting along a common line, low energy atomic structural units are preserved which accommodate elastically angular or/and length misfit(s). Each facet can be considered as a Somigliana dislocation (SD) whose core is extended on the facet. The elastic displacement field of a SD is derived in an anisotropic continuum, for any orientation of the facet relative to a given Cartesian frame. From an atomic point of view, the translation state of the two crystals on each side of the facet is defined. The dislocation content attached to a ledge or a dihedral angle formed by two joining facets along a common side is also analyzed. The local elastic field related to these cases are derived and applications are presented for depicting the positions of the atomic columns in theoretical plots. Comparisons are made with some other theoretical works and HRTEM images. Examples illustrate the application of the Somigliana model to grain boundaries in hexagonal crystals (Mg, WC), and an interphase interface Ni3AI/Ni3Nb.
The Stabilization of Face-Centered-Cubic Titanium
Authors: Jankowski Alan F. , Wall Mark A.
Published: March 2011

The artificial layering of metals can change both physical and structural characteristics from the bulk. The stabilization of such phases often occurs when the component layers are constructed on a nanometric scale. The sequential layering of nickel and titanium has produced the formation of a previously unreported, face-centered-cubic (f.c.c.) phase of titanium.
Effect of Yb Diffusion Barriers on the Properties of In/ n-Hg1−xCdxTe Contacts
Authors: Leech Patrick W. , Reeves Geoffrey K. , Li Yuan H. , Kibel Martyn H.
Published: March 2011

The effect of incorporating a Yb diffusion barrier on the electrical and interfacial properties of In/Hg1−xCdxTe contacts has been examined. Measurements of the specific contact resistance, pc, as a function of Yb layer thickness were performed for a series of semiconductor compositions from x = 0.32 to 0.65. Large changes in pc were evident only at x 0.56 and above a Yb thickness of 2.5nm to 6.0nm, this critical level of layer thickness decreasing with x-value. Analytical examination of the interfaces by Auger electron spectroscopy, secondary ion mass spectroscopy and Rutherford backscattering spectrometry has shown a progressive reduction in the extent of In indiffusion with increasing thickness of the Yb interlayer.
The Effect of Grain Boundary Chemistry on the Slip Transmission Process Through Grain Boundaries in Ni3Al
Authors: Robertson I. M. , Lee T. C. , Subramanian Raja , Birnbaum H. K.
Published: March 2011

The conditions established in disordered FCC systems for predicting the slip system that will be activated by a grain boundary to relieve a local stress concentration have been applied to the ordered FCC alloy Ni3Al. The slip transfer behavior in hypo-stoichiometric Ni3Al with (0.2 at. %B) and without boron was directly observed by performing the deformation experiments in situ in the transmission electron microscope. In the boron-free and boron-doped alloys, lattice dislocations were incorporated in the grain boundary, but did not show evidence of dissociation to grain boundary dislocations or of movement in the grain boundary plane. The stress concentration associated with the dislocation pileup at the grain boundary was relieved by the emission of dislocations from the grain boundary in the boron-doped alloy. The slip system initiated in the adjoining grain obeyed the conditions established for disordered FCC systems. In the boron-free alloy, the primary stress relief mechanism was grain-boundary cracking, although dislocation emission from the grain boundary also occurred and accompanied intergranular crack advance. Because of the importance of the grain boundary chemistry in the models for explaining the boron-induced ductility in hypo-stoichiometric Ni3Al, the chemistry of grain boundaries in well-annealed boron-doped and boron-free alloys was determined by using EDS. No Ni enrichment was found at the grain boundaries examined. These observations are discussed in terms of the different models proposed to explain the ductility improvement in the boron-doped, hypo-stoichiometric alloy.
TEM and HREM Investigation of The Precipitation of Cobalt and Nickel In Polycrystalline Silicon
Authors: Möller H. J. , Chung Juyong , Huang Lan
Published: March 2011

The precipitation behavior of cobalt and nickel at grain boundaries in multicrystalline silicon is investigated. The metals are diffused into the specimens from a surface source between 800 -1000 °C and the precipitation after cooling is studied by conventional and high resolution TEM. Cobalt and nickel disilicide precipitates nucleate both in the bulk and at grain boundaries. They form few large (micrometer size) plate-like or three-dimensional precipitates depending on the cooling rate. Cobalt disilicide with a slightly larger lattice mismatch has a higher tendency to nucleate at large angle grain boundaries. Both suicides nucleate preferentially at coherent twin boundaries forming a few atomic layers thick platelet parallel to the {111} twin plane. HREM and image simulations are performed to analyze the Si / MS12 / twin interface structure (M = Co, Ni).
Comparison Of Thermally- And Irradiation-Induced Grain Boundary Segregation In Austenitic Stainless Steels
Authors: Kenik Edward A.
Published: March 2011

Segregation at grain boundaries in austenitic stainless steels sensitized by either thermal annealing or irradiation was studied by analytical electron microscopy. Characterization of grain boundary compositions in both types of materials was performed by high spatial resolution (≥2 nm) X-ray microanalysis. Whereas similar chromium depletion is observed in both processes, there are differences in the behavior of the other alloying elements and in the mechanisms responsible for the segregation. In thermal sensitization, the nickel/iron ratio and the silicon level observed at grain boundaries are similar to those for the matrix. In cases where little or no precipitation occurs, co-segregation of phosphorus, chromium, and molybdenum occurs at boundaries and interfaces. For radiation sensitization, radiation-induced segregation (RIS) results in enrichment of nickel, silicon, and, in certain cases, phosphorus and in depletion of iron at grain boundaries. There appears to be some synergism between segregation of nickel and silicon, which increases the magnitude of RIS effects. Grain boundary precipitation is often observed in both thermally- and irradiation-sensitized materials. However, the nature and origins of the two types of precipitation are different. The formation of chromium-enriched grain boundary carbides is the cause of the chromium depletion in thermal sensitization. In contrast, the precipitates produced by irradiation are enriched in nickel and silicon and depleted in chromium relative to the matrix and therefore are the result of RIS. Results for thermal- and radiation-induced segregation in manganese-stabilized austenites are compared to that for nickel-stabilized austenites.
Atomistic Simulation of Void Formation in ic Metal Interconnects
Authors: Nandedkar A. S. , Srinivasan G. R.
Published: March 2011

We present an atomistic model to study void formation in aluminum interconnects in integrated circuit (1C) chips. Aluminum single and bicrystals were studied with various concentrations of vacancies and strain levels. It was found that either vacancies or tensile strains could lead to void formation. It will be shown that the void formation can be prevented by maintaining compressive strains in the computational cells.
Possible Mechanism Of The Stress Evolution And Point Defects Generation During The Solid Phase Epitaxial Silicide Growth.
Authors: Italjantsev A. G. , Kuznetsov A.Yu.
Published: March 2011

In this paper we present a model of nonequilibrium point defect generation in the silicon substrate during solid state reactions of the surface suicides formation, resulting from the interaction between the substrate and the thin metal film. The model is based on the following principles. The local stress, which is appearing during each act of the suicide molecule (MexSiy) creation at the suicide - silicon interface, relaxes by the generation of ηv point defects. The point defect generation rate (m is the suicide growth rate) has been defined by the mininimization of the system free energy AG, which includes the enthalpy of chemical reaction ΔG the value of the relaxed elastic energy

μ is the silicon shear modulus, Ω = (xΩMe+yΩSi) is the combined volume of metal and silicon atoms with stoichiometric coefficients, ΔΩ = (ΩMexSiy - Ω), ΩV is the vacancy volume in the matrix; and the term ΔGd = ηVkTln(C/C0) which takes into account the energy of the solid solution of noninteracting point defects, where C° is an equilibrium vacancy concentration and C is the real vacancy concentration. The estimations show that there is not any essential thermodynamic force which may prevent stress relaxation for any reasonable point defect supersaturation. For this case point defect generation rate may be written as jV = m(ΔΩ/ΩV). For the reactions of the initial phase formation in the Me-Si structures the values of ΔG*el, ηV and jV have been calculated and it has been shown that vacancy concentration can reach the values of 1015 - 1016 cm-3 at the regions nearest to the interface even during initial low temperature stages of the Ni, Pt, Cr suicide formation with the metal atoms are predominant moving species.
Synthesis and Characterization of Mo(Ta)/MoSix Microlaminates
Authors: Kung H. , Vyletel B. M. , Ghosh A. K.
Published: March 2011

Vapor phase synthesis approaches were employed to produce laminated microstructures with high temperature phases alternated with ductile phase layers for toughness enhancement. Microlaminates of alternating layers of Mo and cosputtered Mo-Si were deposited on a Si substrate using direct current (DC) and radio frequency (RF) sputtering technique. Microstructural evolution and phase formation after diffusion annealing (900°C, 2 hr) was evaluated using cross-sectional transmission electron microscopy (TEM). Heat treating the microlaminates resulted in the growth of a Mo3Si interface phase between Mo and cosputtered layer and conversion of the amorphous cosputtered layer into crystalline Mo5Si3. A higher Si/Mo ratio in the cosputtered layer caused the formation of dispersed Mo5Si3 grains in Mo layer. The residual stress state was measured by monitoring the curvature change of the microlaminates using a laser beam. By decreasing the bilayer thickness to 1/3, the residual stress is reduced by ∼50%.
Evolution of Structure with Fe Layer Thickness in low Dimensional Fe/Tb Multilayered Structures
Authors: Harris V. G. , Aylesworth K. D. , Elam W. T. , Koon N. C. , Coehoorn R. , Hoving W.
Published: March 2011

The atomic structure of a series of low-dimensional Fe/Tb multilayered structures has been explored using a conversion-electron, extended x-ray absorption fine structure (EXAFS) technique. A structural transition from a close-packed amorphous structure to a body-centered crystalline structure is detected to occur over an Fe layer thickness range of 12.5 Å to 15.0 Å (Tb thickness is held constant at 4.5 Å). Magnetic properties, specifically, magnetization, anisotropy field, and Kerr rotation angle, are measured and found to change significantly in response to this transition. Exploitation of the polarization properties of synchrotron radiation allowed for the description of the atomic structure both perpendicular and parallel to the sample plane.
Dynamics and Atcmic Strujciure of Martemite-Austenite Interfaces :
Authors: Chen S. , Clapp P. C. , Rifkin J. A.
Published: March 2011

The structure of the lowest energy interface between an hcp austeidte phase and an foc martensite phase of similar atomic volumes has been simulated by annealing a disordered region between the two perfect lattices until semi-coberent intergrowth occurred. The two structures were oriented so that the closepacked planes were parallel, and closepacked directions were aligned. The dynamics of this interface and the structure which it evolved as it moved was then studied by applying a transformation driving force through the use of an Embedded Atar Method potential. Initially the interface moved in a reconstructive, diffusive manner but eventually it developed a highly mobile, diffusionless form which moved at about one third of the shear sound velocity. The structure of this rapidly moving interface could be analyzed in terms of three different types of Shockley partials arranged in sequence, but passing at slightly different times. This structure agrees with some elements of a model previously proposed by Christian to describe the transformation in pure Co, and agrees with other elements of a proposal of Mcbreer, Lunggren and Franck to explain their observations of the transformation in 4He. Neither fully explain our observations.
Characterisation of Interfaces in SiGe Superlatrlces by Combined Grazing Incidence X-Ray Fluorescence and Reflectivity
Authors: Powell Adrian R. , Bradler Jaroslav , Thomas Charles R. , Kubiak Richard A. , Keith Bowen D. , Wormington Matthew , Hudson John M.
Published: March 2011

X-Ray reflectivity enables the determination of interface and surface roughness along with the variations present in the electron density. Total reflection X-ray fluorescence allows surface analysis with high sensitivity and quantification. By use of grazing angle x-ray fluorescence taken simultaneously with the reflectivity measurements, over a range of angles near the critical angle, it is possible in principle to produce a depth profile of each element, with a composition sensitivity of 0.0002%. A silicon-germanium single layer was used to calibrate the instrument and a Si-Ge 5- period superlattice for a demonstration measurement.
Interface Reactions in Bilayers of Aluminum and Nickel-Chromium Alloy
Authors: Heald S. M. , Tan Zhengquan , Jayanetti J. K. D.
Published: March 2011

Glancing angle EXAFS and x-ray reflectivity are used to study the interface reaction between nickel-chromium alloys and aluminum. The two metals are found to react independently with Al, with the first reactions taking place at temperatures similar to those found for the pure metals. This means that Ni reacts first with Al to form NiAl3, leaving behind a Cr-rich region at the interface. In this Cr-rich region some of the Cr transforms to the bcc structure from the fcc form of the alloy. At higher temperatures Cr reacts to form CrAl7, and there is no evidence for ternary compound formation. Samples were also prepared with a controlled O contamination at the interface, and it inhibits the reaction much the same as for the pure metal cases. The Ni reaction is not identical to the pure sample case, since the presence of Cr slows down the reaction, and inhibits the initial reaction in the as-prepared bilayers.
Structural Properties Of Co/Re Superlattices
Authors: Huai Y. , Cochrane R. W. , Shi Y. , Fischer H. E. , Sutton M.
Published: March 2011

The structures of equal-thickness Co/Re multilayer films and several Co/Re bilayer films have been investigated by X-ray diffraction at low and high angles. Analysis of low-angle reflectivity data from bilayer films indicates that interfacial intermixing is limited to three monolayers and that the two interfacial configurations are different. The high-angle X-ray diffraction data show that multilayer films have coherent interfaces and a highly textured structure with hep [002] orientations normal to the film plane for periods 21 Å ≤ Λ ≤220 Å. Detailed structures have been determined by fitting the X-ray spectra to calculated ones using a trapezoidal model. The results indicate that samples with 42 Å≤ Λ ≤220 Å have relatively sharp interfaces, in good agreement with the bilayer results. In addition, an out-of-plane expansion of the Co (002) layer is observed in samples with large Λ and results from structural disorder leading to a reduced atomic density. For Λ <21 Å the interfaces arise from the rougher surfaces of the deposited layers.
Determination Of Intermetallic Formation Mechanism Using Differential Scanning Calorimetry Of Multilayered Thin Films
Authors: Schlesinger T. E. , Prokes S. M. , Cammarata R. C.
Published: March 2011

The ability to determine which growth mechanism (interface-reaction-rate-limited vs. diffusion-limited) of intermetallic formation by interfacial reactions using differential scanning calorimetry (DSC) is demonstrated. Suicide formation in multilayered thin films of chromium and amorphous silicon was chosen as a model system. It is shown that suicide formation in this system followed a linear rate law corresponding to an interface-reaction-rate-limited growth mechanism. An activation energy and pre-exponential for the rate constant were determined.
A Comparison Of The Corrosion Behaviour Of Nanocrystalline And Normal Crystalline Nickel
Authors: Rofagha R. , Langer R. , El-Sherik A. M. , Erb U. , Palumbo G. , Aust K. T.
Published: March 2011

The effect of grain size on the corrosion behaviour of nickel in 2N sulphuric acid is evaluated by potentiodynamic testing and characterization of the corrosion morphology for grain sizes ranging from 100μ to 32nm. The influence of the grain boundary component on key electrochemical parameters (free corrosion potential, passivation current density and potential, transpassive dissolution rate) is discussed.
Interface Structure Of Iron Oxide Thin Films Grown On Sapphire And Single-Crystal MgO
Authors: Anderson Ian M. , Tietz Lisa A. , Barry Carter C.
Published: March 2011

The ability to tailor thin film interface structure is illustrated by the growth of thin ferric oxide films using different deposition parameters. Low-pressure chemical vapor deposition (CVD) has been used to grow α-Fe2O3 on sapphire while pulsed-laser ablation (PLA) followed by low temperature oxidation has been used to grow γ-Fe2O3 on MgO. The structure of the films and of the film-substrate interfaces has been characterized using transmission electron microscopy (TEM) and selected-area diffraction (SAD) in plan view. The different deposition techniques lead not only to the growth of two different polymorphs of ferric oxide but also to different growth mechanisms and film-substrate interface structures. In addition, changes in the thermodynamic conditions during deposition can give rise to different interface structures between the individual structural domains of the film.
High Resolution Electron Microscopy Of Intercalated Phases In The Y-Ba-Cu-0 System
Authors: Burmester C. P. , Fendorf M. , Wille L. T. , Gronsky R.
Published: March 2011

High resolution transmission electron microscopy (HRTEM) is used to investigate the transformation mechanism responsible for the occurrence of the many stable layered phases in the pseudo-binary Y2Ba4Cu6+xO14+x system. In particular, HRTEM results are compared with microstructural configurations generated by an earlier theoretical study which modeled this transformation by means of an intercalation mechanism. HRTEM images of partially transformed Y-Ba-Cu-O reveal that the predominant structural change is limited to the CuO planes. The location of the transformation front, revealed in the micrographs by the presence of these partial dislocations, suggests that the transformation is nucleated at grain boundaries and internal surfaces within the material. The observation of local CuO layer ordering along the [001] direction is taken as evidence for the presence of longer range interactions. A two-dimensional approximation to the bulk Monte Carlo simulation incorporating long range screened Coulomb [001] interactions is used to investigate the possibility and nature of local, transient stage orderings.
Misfit Dislocation Nucleation Sites and Metastability Enhancement of Selective Si1−xGex/Si Grown by Rapid Thermal Chemical Vapor Deposition
Authors: Liu C. W. , Sturm J. C. , Schwartz P. V. , Fitzgerald E. A.
Published: March 2011

A quantitative model of the effect of the selective growth on dislocation density has been developed and compared to experiments. It is concluded that the dominant dislocation nucleation source in the selective areas occurs at the specific heterogeneous sites at edges of the selective areas. This edge nucleation can be controlled by adjusting the orientation of the sidewalls.
Growth of Interfacial Phases: Effects of External and Internal Stresses
Authors: Albert D. E. , Yavari A. R.
Published: March 2011

Cu/Zr-type multilayers prepared by cold-rolling have been subjected to cold and hot pressing until the onset of crystallization. It is found that application of a uniaxial stress perpendicular to the plane of the layer interfaces accelerates both the growth rate of amorphous interlayers and the onset of subsequent crystallization. These effects have been attributed to stress-induced flow parallel to the interfaces that helps relax diffusion-induced internal stresses and increases interfacial reaction constants controlling crystalline layer formation at the amorphous/Zr layer interfaces.
Computer Simulation of Plastic Deformation of Small Crystals
Authors: Doyama Masao
Published: March 2011

The deformation of body centered iron whiskers has been simulated. The iron whisker has a very sharp yield stress. Dislocations are created in a small coppe crystal. A higher stress was needed to create the first partial dislocation but less stress to create the second partial dislocation.
Application of Stress Measurement to the Study of Thermally Activated Processes in Thin-Film Materials
Authors: Von Preissig F. J. , Nix W. D.
Published: March 2011

Changes in mechanical stress occurring in unpatterned thin films on substrates at elevated temperatures can yield information about the kinetics of the controlling processes. In this study, a specialized furnace allowed stress at elevated temperatures to be measured by the optical-lever method. The furnace was designed for good temperature control, short thermal transient periods, accurate stress measurement with low scatter, and control of the gas ambient. Stress changes in phosphosilicate glass films measured during exposure to steam at 110–150°C allowed water diffusion coefficients to be calculated. Diffusivity decreased with increasing phosphorus content and with pre-annealing treatments. The effective activation energy for water sorption was about 0.43 eV. Analysis of stress changes associated with crystallization of amorphous silicon at temperatures near 600°C yielded an effective activation energy of 3.1 eV and a density change of about 1% for the transformation.
Characterization of Thin Films by Internal Friction Measurements
Authors: Bohn H. G. , Su C. M.
Published: March 2011

ABSTRACT: Internal friction has been employed to characterize various properties of thin Al and Al-alloy films. The grain boundary relaxation peak was used

a) to determine the activation energies for grain boundary diffusion in the alloy films,

b) to investigate the influence of impurities on the grain boundary diffusion in Al at concentration levels as low as 300 ppm, and

c) to get information about the adhesion strength between the film and the substrate.
In Situ Measurement of Stresses in Thin Films
Authors: Abermann Reinhard
Published: March 2011

In this paper the results of experiments are summarized in which the internal stress (i.e. force per unit width) of thin films was measured in situ under UHV conditions with a bending beam apparatus. It is demonstrated that characteristic types of stress vs. thickness curves can be correlated with different growth modes (i.e. columnar grain growth and island growth) caused by differences in the adatom mobility of the deposited material. With a selection of thin film systems it is then shown that stress measurements can be used to study the effect of gas incorporation, of gas diffusion from the substrate, of reaction with the substrate and of the substrate temperature on the growth and structure of a thin film. Finally it will be demonstrated that stress measurements can even be used to study gas adsorption on vapor deposited films.
Determination of the Mechanical Properties OP Integrated Circuit Packaging Materials using a Focused Acoustic Beam Technique
Authors: Zhang De , Crean Gabriel M.
Published: March 2011

A novel method for the measurement of the mechanical properties of integrated circuit interconnection and packaging materials using a conventional acoustic microscope lens, is presented in this paper. This technique allows the simultaneous generation and detection of longitudinal (LW) and shear (SH) acoustic waves in a material system based upon acoustic mode conversion principles at a water-solid interface. Experimental results obtained using a 50 MHz acoustic lens are presented for a range of ceramic materials and compared with published data. Acoustic ray propagation theory is employed to analyse the experimental results.
The Choice OP Optimal Microhardness Testing Conditions for Amorphous and Polycrystalline Films
Authors: Manika I. , Maniks J.
Published: March 2011

The microhardness of polycrystalline and amorphous coatings on substrates of various hardness has been studied in a wide range of loads. The limits for indentation depth providing optimal conditions for microhardness testing have been found. Basing on the results of integral hardness testing of coated samples at comparatively high loads, a method has been proposed for the microhardness and thickness evaluation.
Observation of Glass Transition Temperatures in Polymeric Thin Films by Wafer Curvature Measurements
Authors: Townsend P. H. , Huber B. S. , Wang D. S.
Published: March 2011

Wafer bending measurements have been used to study the glass transition temperature, Tg, of thin coatings of polystyrene and polycarbonate on Si wafers. The observed values of Tg agree with DSC and TMA measurements on bulk samples. The evolution of the substrate curvature has been used to examine the behavior of Tg in thin epoxy films and coatings derived from divinylsiloxane bisbenzocyclobutene, mixed stereo and positional isomers of 1, 3-bis(2-bicyclo[4.2.0]octa-1, 3, 5-trien-3-ylethenyl)-1, 1, 3, 3-tetramethyl disitoxane (CAS 117732–87–3). The dependence of the Tg of the epoxide coatings is studied as a function of the cross-linking. The evolution of the Tg in the benzocyclobutene coating is found to be a monotonie function of the level of conversion of the polymer network.
The Interactions Between Misfit Dislocations in InGaAs/GaAs Interfaces.
Authors: Kightley Philip , Goodhew Peter J , Beanland Richard
Published: March 2011

The reactions between misfit dislocations arriving by glide at the interface between an In0.12Ga0.88As/GaAs multilayer and a GaAs substrate are analysed and reported. The glide forces for the (a/2)<110> dislocations are calculated as a function of vicinal tilt from (001) to (100). It is observed that the 4% changes in the magnitude of the force for a 2° vicinal angle are not sufficient to significantly alter the relative linear densities of the different types of dislocation.
Experimental Deformation Mechanics of Materials from their Near-Atomic-Resolution Defect Images
Authors: Choi H. C. , Schwartzman A. F. , Kim K.-S.
Published: March 2011

A novel approach to quantitative interpretation of high-resolution electron microscopy images of defects in materials has been developed. The emphasis of this paper is on the methodology, which has been named Computational Fourier Transform Moiré Analysis. The essential principle of this technique is to extract an accurate displacement field about a defect from its near-atomic-resolution picture using digital Fourier transformation procedures. From this data, the displacement gradient can be calculated which yields much information on the experimental deformation mechanics of the material under investigation. As a by-product, we produce the computational Moiré pattern without the need of an external perfect reference lattice image normally associated with the interference phenomena. This method is illustrated using a bounding Frank partial dislocation for a Frank loop of the vacancy type. Results are presented on its strain field, Burgers vector and dislocation core shape and dimensions. Further mention will be made on the types of J-integral calculations that can result from this experimental study.
Finite Element Simulation of Indentation Behavior of thin Films
Authors: Madsen D. T. , Giovinazzo R. J. , Ritter J. E.
Published: March 2011

Nanoindentation experiments are now widely used to study the elastic and plastic properties of thin films. Simulation of these experiments has been performed using finite element analysis. Results show the large influence that pile-up or sink-in behavior have on hardness calculations. Results also show that a compliant substrate significantly affects the measured hardness of a stiffer coating. The measured hardness of a compliant coating is less effected by a stiffer substrate.
Microstructural Characterization of SiGe Heterolayers
Authors: David Theodore N. , Fejes Peter , Tomozane Mamoru , Liaw Ming
Published: March 2011

SiGe is of interest for use in heterojunction-bipolar transistors, infrared detectors and field-effect transistors. In this study, graded SiGe heterolayers grown on Si, and heterolayers grown on SIMOX by CVD, were characterized using TEM. The graded-heterolayers consisted of ten layers of Si1-xGex on substrate silicon. Misfit dislocations were present at interfaces in the bottom 4–5 layers of the heterostructure. This conforms with predictions from qualitative strain-energy considerations. The greatest density of misfit dislocations was present at the Si1-xGex interface between the bottom two layers of the heterostructure. Dislocations were observed to extend out of the interface and up into the heterolayer structure. The defects were found to interact with interfaces in the structure and finally cease extending upwards towards the surface of the wafer. In addition to graded heterolayers, SiGe heterolayers grown on SIMOX were also investigated. The structures consisted of epi-silicon grown on a Si/Si1-xGex superlattice which was in turn grown on a Si/SiO2 (SIMOX) structure. The behavior of defects in the layers was of interest. TEM characterization showed a large density of extended-defects present in the layers. Dislocations were observed to originate at the SIMOX oxide/Si interface, propagate up through the SiGe superlattice and into the epi-Si layer. Some dislocations were found to interact with the SiGe superlattice and cease propagating up towards the top of the wafer. SiGe superlattices with a higher concentration of Ge are more effective in reducing defect propagation towards the surface of the wafer.
Observations of the Solid Phase Epitaxial Regrowth for GaAs/Si
Authors: Kightley Philip , Goodhew Peter J , Augustus Peter D , Bradley Robert R
Published: March 2011

The changes in defect structure caused by an anneal are studied by TEM for thin GaAs layers on Si. A low growth temperature of 450°C is always used for the first 300Å. When it is first deposited this layer contains considerable disorder which consists of planar defects, {112} epitaxy and an irregular distribution of dislocations. Annealing of the layer gives rise to a solid phase regrowth that consumes the misoriented and much of the twinned crystal and produces regular misfit dislocation arrays. Continued growth at high temperature can reduce the twin densities to below the detection limit of TEM. It is this solid phase transformation of this layer that allows good epitaxy to continue.
Structural Characterization of Multilayers Using X-ray Diffraction
Authors: Clemens B. M. , Bain J-A. , Payne A. P. , Hufnagel T. C. , Brennan S. M.
Published: March 2011

Structural deviations from ideal layering of bulk constituents can have dramatic effects on the properties of multilayered materials. We discuss three examples of the use of x-ray diffraction in non-standard geometries to examine these effects. In Mo/Ni multilayers, we use asymmetric diffraction and grazing incidence x-ray scattering (GIXS) to deduce the strain and intermixing. We find that coherency stresses between the BCC Mo and FCC Ni planes play a major role. In the Fe/Cr system, we use rocking curves and asymmetric scans about the small angle superlattice lines to investigate the nature and extent of layer roughness. We find that conformai roughness dominates our best samples, while non-conformal roughness increases with sputter deposition pressure. In the Gd/Co system, we use in-situ GIXS to investigate amorphization reaction during deposition. We find a strong diffusional asymmetry and rapid reaction during growth.
Effect of Structure on the Anomalous Mechanical Properties of Metallic Superlattices
Authors: Schuller Ivan K. , Fartash A. , Fullerton Eric E. , Grimsditcht M.
Published: March 2011

The mechanical properties of metallic superlattices have been shown to exhibit anomalous properties. Several of the elastic constants are found to exhibit anomalies which are correlated with structural anomalies in lattice mismatched systems which do not form solid solutions. Lattice matched systems which form solid solutions in their thermodynamics phase diagram, show much smaller elastic anomalies and no structural anomalies. Anomalous plastic behavior, on the other hand, seems to be present in both types of superlattices, indicating that the plastic behavior is possibly defect induced. Detailed quantitative structural measurements combined with comprehensive mechanical properties hold the promise of determining the physical origins of the anomalous properties of metallic superlattices.
Atomistic Simulation of the Nanoindentation of Diamond and Graphite Surfaces
Authors: Harrison J. A. , Colton R. J. , White C. T. , Brenner D. W.
Published: March 2011

Molecular dynamics simulations which make use of a many-body analytic potential function have been used to study the nanometer-scale indentation of diamond and graphite. We find that the simulation correctly reproduces experimentally determined trends in load versus penetration data. As a result, trends in mechanical properties, e.g. Young's modulus, are also reproduced.
Small Scale Yielding at a Crack Normal to the Interface Between an Elastic and a Yielding Material
Authors: He Ming Y. , McMeeking R. M. , Zhang Ning T.
Published: March 2011

By using the elastic singular field as a prescribed loading condition, small scale yielding solutions are obtained for a crack normal to the interface between a brittle and a ductile material. Results for both a crack in the brittle material and one in the ductile material are obtained by finite element analysis. The crack tip fields obtained by the finite element analysis are compared with the asymptotic solutions. It is found that near the tip the stress fields approach the asymptotic solutions. If the crack is in the brittle material, the high triaxial stresses are developed near the interface ahead of the crack tip.
Tribology and Abrasive Wear of Mo Lecularly Doped Polycarbonate Coatings
Authors: Murti D. K. , Odell P. G. , Mizes H. A.
Published: March 2011

Molecularly doped polymers are widely used in copiers and printers. During the imaging process, toner particles and the cleaning blade wear the photoconductor drum as it rotates. This paper quantizes the abrasive wear of molecularly doped polycarbonate coatings. No clear correlation is found between the wear rate and measured mechanical properties. The surface topography is dominated by a series of parallel grooves with a spacing of approximately 0.1 pm.
A saw Sensor Study of the Relative Adhesion and Surface Properties of Polyimide Films
Authors: Galipeau D. W. , Feger C. , Veteldmo J. F.
Published: March 2011

A surface acoustic wave (SAW) sensor is used to study the relative humidity response of polyimide films where interfacial and surface properties are varied. The relationship between these responses and the relative adhesion strength of these films is of particular interest since it could have application as a nondestructive, quantitative measure of adhesion strength. The results show clear differences in the SAW humidity response for cured and uncured films. There are also significant differences in the SAW humidity response for films applied with and without adhesion promoter. In addition the humidity response has proven to be particularly sensitive to the surface treatment of the polyimide film. These results suggest applications of the SAW sensor as a cure indicator, an in-situ sensor for the monitoring of film surface properties in process control applications and as an adhesion sensor.
Diamond-Like Carbon Coating—It'S Application for Polymeric Substrates
Authors: Kimock Fred M. , Hsieh Alex J. , Dehmer Peter G. , Yip Pearl W.
Published: March 2011

We report on a recently commercialized Diamond-Like Carbon (DLC) coating that has been deposited on polycarbonate at near room temperature, via a unique ion beam system. Aspects of high speed impact behavior, chemical resistance, abrasion resistance, and thermal stability of the coating are examined. Results of scanning electron microscopy studies indicate that adhesion of the DLC coating is very good; no delamination of the coating was found on ballistically tested specimens. The well-bonded DLC coating did not cause the impact performance of polycarbonate to become brittle. Chemical exposure test results show that the DLC coating is capable of protecting polycarbonate from chemical attack by aggressive organic liquids. These ion beam deposited DLC coatings have considerable potential as protective coatings for optical systems.
Electromigration Damage by Current Induced Coalescence of Thermal Stress Voids
Authors: Børgesen P. , Korhonen M. A. , Sullivan T. D. , Brown D. D. , Li C.-Y.
Published: March 2011

According to a new electromigration model, small thermal stress induced voids remain trapped at grain and phase boundaries, growing under an electric current. When they reach a ‘threshold’ size, migration and coalescence leads to rapid line failure. Predictions are compared to experimental results for Al, Al(0.6%Si), and Al(1.6%Cu) lines.
Defect-Characterization in Implanted Locos + Trench-Isolated Structures
Authors: David Theodore N. , Vasquez Barbara , Fejes Peter
Published: March 2011

As device dimensions decrease in silicon integrated-circuits, conventional LOCOS (local-oxidation of silicon) isolation becomes inadequate to meet dimensional demands. Variations on LOCOS are therefore being explored for further miniaturization of devices. One such variation involves poly-buffered LOCOS + trench-isolation (PBLT). In this study, PBLT structures were characterized using TEM. Wright-etched cross-section SEM micrographs showed etch-pits associated with a combination of high-dose (> 5E14 cm-2) phosphorous implants and PBLT isolation. TEM characterization showed that dislocations were formed in the structures for a combination of high-dose (1E15 cm-2) phosphorous implants (followed by an anneal) and PBLT isolation. Structures exposed to lower-dose (1E14 cm-2) implants showed no defects and neither did 1E15 implanted structures prior to annealing. The results are modelled in terms of the stress configurations present in the structures, and in terms of dislocation-sources resulting from implantation-related dislocation-loops. The dislocation-sources operate in the presence of stresses associated with the isolation-trenches. Glide-loops form, which then grow in response to stresses in the structures and dislocations result on glide planes.
Electromigration Behavior of Aluminum Films Deposited by Partially Ionized Beam.
Authors: Kononenko O. V. , Fionova L. K. , Matveev V. N.
Published: March 2011

Aluminum films deposited by partially»ionized beam were stressed by a current density of 2×106 A/cm2 at a temperature of 300°C. The films prepared at the acceleration voltage of 5 kV lived over 200 hours.
Characteristics of Palladium Thin Films Deposited by the Ionized Cluster Beam Technique
Authors: Huffman Maria , Kalkur T. S. , Kammerdiner L. , Kwor R. , Levenson L. L. , Reeder M.
Published: March 2011

An ionized cluster beam (ICB) source was used to deposit Pd onto oxidized silicon substrates. The ICB source was operated in both the neutral mode (no ionization and no acceleration) and in the ICB mode with ionization and acceleration voltages at 3 kV and 6 k.V. Also, substrate temperatures were varied between 100°C and 400°C. The Pd film thicknesses were generally between 1, 200Å and 1, 800Å, with one film thickness about 500Å. The films were examined by transmission electron microscopy (TEM), transmission electron diffraction (TED), and x-ray diffraction (XRD). Grain size measurements by TEM and XRD showed that ionization and acceleration of Pd resulted in a slight increase in grain size compared to films deposited without ionization or acceleration at any substrate temperature. However, the grain size increased significantly as the substrate temperature rose. XRD showed that all ICB deposited Pd films have significant (111) texturing as determined by comparison to XRD data for Pd powder. For Pd films deposited at 400°C, almost all grains were oriented with the (111) planes parallel to the substrate surface. The electrical conductivity of all Pd films was comparable to that of bulk Pd.
Crystallite Dimensions and Strain in Poly-Si and Ti-Silicide Thin Films Measured with Grazing Incidence X-Ray Diffraction
Authors: Leiberich A. , Roy P. K.
Published: March 2011

The present study describes the measurement of microcrystalline grain dimensions and crystallite strain for polycrystalline silicon (poly-Si) and titanium suicide, using grazing incidence X-ray diffraction (GIXRD). A variety of poly-Si sample configurations were synthesized by different low pressure chemical vapor deposition (LPCVD) processing techniques. Selected samples were subsequently processed by phosphorous diffusion doping and reaction with thin titanium layers. Characterization with GIXRD reveals differing crystallite grain dimensions, ranging from =80Å to =900Å. Crystal strain was measured in direction perpendicular to (111) lattice planes. Phosphorous diffusion doping is shown to remove this (111) strain, in addition to increasing crystallite grain dimensions. The GIXRD characterization, which measures a specific fraction of the sample crystal texture, indicates that deposition rate modulated poly-Si LPCVD reduces (111) microscopic strain in poly-Si films two-fold, compared to conventional poly-Si deposition. The crystallite dimensions of conventional poly-Si, are found to peak approximately in direction perpendicular to (110) planes. The same trend is observable for deposition rate modulated poly-Si, where grain dimensions, measured in [110] direction, are reduced by =30%. Larger crystallite dimensions were measured in direction perpendicular to (110) planes, for both cubic poly-Si and orthorhombic Ti-silicide layers, suggesting the presence of preferred crystallite growth directions, resulting in anisotropie crystallite grain dimensions.
The Effect of Deposition Temperature on the Microstructure of Lpcvd Polysilicon Films
Authors: Hangas J. , Liu D. R. , Oei D. G. , McCarthy S. L. , Peters C.
Published: March 2011

The microstructure, of unannealed and annealed polysilicon films was studied using TEM and XRD. The LPCVD films were grown at 600°C and 620°C with 320 mTorr of silane, and at 580°C with 220 mTorr of silane. The substrates were [001] Si with a thin oxide film. The stress state of the films changed from compressive at 580°C and 620°C, to tensile in a narrow region around 600°C. The same materials were annealed at 1100°C. The unannealed films vary from partially amorphous at 580°C, where the slowest growth rate was observed, to randomly oriented and equiaxed at 600°C, to columnar and highly oriented at 620°C. The grains in the 620°C material have a high stacking fault and polytype density, and it was proposed that these occurred on growth, and not from dislocation motion. The grain size increased from 40–250run to 100–300 nm in the 600°C samples when annealed at 1100°C, and the density of twins and stacking faults was reduced. The hexagonal phase was observed only in unannealed materials in SAED and as broad “wings” at the base of the llld.c (diamond cubic) peak in XRD. Within the limits of SAED, no change in lattice parameter of the hexagonal phase was observed.
Metal Colloids in Oxides*
Authors: Narayan J. , Chen Y. , Moon R. M.
Published: March 2011

A method, based upon subtractive coloration or high-temperature reduction, was developed to produce metal precipitates or colloids in oxides. The structure, symmetry, morphology and composition of precipitates were analyzed by analytical electron microscopy and neutron scattering technioues. In the MgO:Ni system, the colloids were coherent nickel precipitates having a fcc structure (a0 = 3.52 Å), and occasionally a bcc structure (a0 = 2.88 Å). The coherent precipitates were analyzed to have either <100>m,∣∣ <111>p or m ∣∣<100>p matrix-precipitate orientation relationship depending upon the high-temperature reduction treatment. The optical absorption spectra of these materials were characterized by broad optical bands centered near 2.2 and 5.0 eV. By changing the size distribution of the precipitates, it was possible to obtain optical spectra of these materials suited for solar selective absorber applications. The dislocations and sub-boundaries provided nucleation sites for the formation of precipitates, and decreased the temperature of reduction. By providing sources of dislocations, the precipitates enhance the ductility and inhibit the propagation of cracks.