bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ternary Phase Formation in 95Pb-5Sn Flip-Chip Solder Bonds
Authors: Mockler Alan J. , Goodhew Peter J. , Logan Elizabeth A. 
Published: March 2011

AbstractThe microstructure of 95Pb-5Sn flip-chip solder bonds deposited on Cr/Cu/Au metallisation pads has been studied using both light and electron analysis techniques. The presence of Sn-Cu- Au ternary intermetallic phases was detected within the Pb-rich matrix at significant distances from the originally deposited interface. The distribution of the phases present after the solder has undergone a reflow heat treatment can be interpreted using recent equilibrium ternary diagram data. An investigation was also made into the effects of various non-reflow heat treatments at carefully chosen temperatures, to qualitatively evaluate the extent of solid state diffusion and the resultant phase distribution.
Computational Problems in Orthopaedic Biomechanics
Authors: Taylor Dean 
Published: March 2011

AbstractTotal joint replacements such as the hip and knee result in composite structures. Proper design of these devices and selection of particular devices requires understanding of the structural response of the resulting composite structure of plastic, metal, interface, and human bone. The problem is challenging because of complex geometry, non-homogeneous material properties (dense cortical bone and spongy cancellous bone), and time varying material properties (bone remodeling). Bone is a active material which responds over time to applied load, changing the density and Young's modulus.This paper addresses several computational issues. Remote sensed data such as computerized tomography scans are used to create finite element models. Nonhomogeneous material properties are represented in finite element models using shape functions. This results in a unique material property for each Gauss point. Finally, stochastic finite elements methods are used to model material variation and uncertainty. Both Monte Carlo and First Order Second Moment methods are used. These problems are particularly well suited for high-level parallelization schemes on multiple instruction multiple data machines.
Density Functional Methods and Applications to Materials Problems
Authors: Li Y. S. , Daelen M. A. van , King-Smith D. , Wrinn M. , Wimmer E. , Newsam J. M. , Klitsner T. , Sears M. P. , Carlson G. , Nelson J. , Allan D. C. , Teter M. P. 
Published: March 2011

AbstractDensity functional theory provides a first-principles approach for computing the geometric and electronic structures, and a wealth of corresponding properties, of a wide range of materials types and compositions, including bulk solids, surfaces, defects and clusters of molecules. Parallel advances in hardware performance, implementation strategies and algorithms have all contributed to a rapid growth in the number of important applications. Recent developments under each of these themes are outlined and the breadth of current applications is illustrated by typical examples. Issues associated with the implementation and performance of density functional methods on parallel computer architectures are discussed.
Bending of Flex Leads During Thermal Cycling
Authors: Shi L. T. , Tong H. 
Published: March 2011

AbstractA three dimensional finite-element stress model was used to simulate the lead bending incurred during thermal cycling of a Flex connector joined to a silicon carrier via an eutectic solder. Three different coating conditions (no coating, with a polyimide coating, and with a silicone coating) were simulated. With the polyimide coating, lead bending was found to occur at the corner inner leads of the Flex as a result of the plastic strains accumulated there during thermal cycling. In the case of silicone, the corresponding plastic strains grew during the first thermal cycle but saturated subsequently, confirming the negligible lead bending observed experimentally. For the case of no coating, the highest plastic strain was found to be borne in part by the polyimide film at its edge and thus no significant bending was observed. In all cases, the results provided by the model agree well with the experimental observations.
Characterization of Conductive Anodic Filament (Caf) by X-Ray Microtomography and by Serial Sectioning
Authors: Stock S. R. , Dollar L. L. , Freeman G. B. , Ready W. J. , Turbini L. J. , Elliott J. C. , Anderson P. , Davis G. R. 
Published: March 2011

ABSTRACTX-ray microtomography is used to nondestructively section printed wiring boards in which conductive anodic filaments (CAFs) had grown, Quantification of the spatial distribution of copper is compared for microtomography and for serial sections obtained in SEM with backscattered electrons. The agreement between the techniques is excellent and indicates that microtomography may be used confidently to follow the subsurface growth of CAFs.
Reliability Studies on Ge High Density Interconnect (Hdi) Modules
Authors: Paik Kyung W. , Bernard Edward S. 
Published: March 2011

ABSTRACTConsiderable mechanical and environmental reliability testing as defined by MIL-STD-883 has been performed on GE HDI modules in both hermetic and nonhermetic configurations. The tests involving temperature cycling, temperature bakes, thermal shock, power cycling by self-heating, vibration, centrifuge and drop shock showed no change in the overlay or in the performance of the underlaying chips on the substrate. As an additional reliability test, the effect of humidity cycling (45° - 95° relative humidity) on nonhermetic HDI substrates has been also investigated. Any noticeable failures and degradation of metallization were not observed by humidity cycling itself at room temperature. Both the 883 and humidity cycling test could lead to the conclusion that HDI is a robust MCM-D technology. In addition, extensive studies on the residual stress analysis of the thin film layers of metal and polymer during fabrication and thermal cycling have been performed using the Flexus laser beam bending instrument. The study results predicted that failure of overlay HDI such as delamination between layers is less likely because of lower in-plane stresses than in conventional spin-coated and cured polyimide.
Light Scattering Measurements of Surface Roughness in Molecular Beam Epitaxy Growth of GaAs
Authors: Lavoie C. , Nissen M. K. , Eisebitt S. , Johnson S. R. , Mackenzie J. A. , Tiedje T. 
Published: March 2011

AbstractIn-situ measurements of diffuse light scattering at λ = 457 nm are reported from the surface of GaAs films during growth by molecular beam epitaxy. Three different scattering angles are measured simultaneously corresponding to spatial frequencies in the surface roughness of q = 0.9, 12, and 17 μm−1. During growth the initial surface roughness caused by the oxide desorption decreases at high spatial frequencies and increases at low spatial frequency. The low spatial frequency roughness corresponding to scattering vectors parallel to [110] increases more rapidly during growth than for scattering parallel to [111].
The Utility of Laser Light Scattering in Assessing the Mixability of Reagents for Chemical Vapor Deposition
Authors: Ni Bin , Reck Gene P. , Proscia James W. 
Published: March 2011

AbstractThe premixability of reagents used in chemical vapor deposition reactors is important to insure that gas feed lines and nozzles do not become clogged with particulates during operation. Even if reactants are to be kept separate until introduced into a reaction chamber, it is desirable to limit the number of particles formed. A reactor which utilizes laser light scattering to monitor particulate formation when gaseous reagents are mixed is described. The reaction of tin (IV) chloride with water is commonly used to produce tin oxide films by chemical vapor deposition. It was found by the light scattering experiment that at temperatures above about 110°C the number of particulates formed is greatly reduced. Therefore, it would be most desirable that these reagents be mixed above this temperature when depositing tin oxide from this reaction. The reaction of titanium tetrachloride with various amine was also investigated by this method. This reaction has been demonstrated to produce titanium nitride above 450°C. For each case, it was observed that there was a temperature above which the number of particulates was significantly reduced. This temperature was always below the optimal temperature for producing titanium nitride films.
Photoreflectance Characterization of Etch-Induced Damage in Dry Etched GaAs
Authors: Glembocki O.J. , Tuchman J.A. , Ko K.K. , Pang S.W. , Giordana A. , Stutz C.E. 
Published: March 2011

AbstractPhotoreflectance has been used to characterize the etch-induced damage in GaAs processed in an Ar/Cl2 plasma generated by an electron-cyclotron resonance (ECR) source. We show that the damage is localized to the surface and that it is most influenced by the RF power, with little effect from the microwave power. The Fermi-level is observed to be unchanged in n-GaAs and remains near midgap, while for p-GaAs, the Fermi level shifts from near the valence band to midgap. Etch-induced anisite defects are proposed as a possible source of the damage.
Photoreflectance Characterisation of Reactive Ion Etched Silicon
Authors: Murtagh M. , Beechinor J. T. , Herbert P. A. F. , Kelly P.V. , Crean G. M. , Jeynes C. 
Published: March 2011

AbstractReactive ion etching (RIE) of p-type 2-3 †cm resistivity silicon (100) was characterised using Photoreflectance (PR), Rutherford Backscattering Spectrometry (RBS) and Spectroscopic Ellipsometry (SE). Isochronal (5 minutes) etching was performed at various DC etch biases (0-500V) using a SiCl4 etch chemistry. The substrate etch rate dependence on applied bias was determined using mechanical profilometry. A distinct shift in the A3–A1 Si transition and significant spectral broadening of the room temperature PR spectra was observed as a function of etch bias. Photoreflectance results are correlated with RBS, SE and etch rate analysis. It is demonstrated that the PR spectra reflect a complex, competitive, plasma-surface interaction during the RIE process.
In-situ Multilayer Film Growth Characterization by Brewster Angle Reflectance Differential Spectroscopy
Authors: Dietz N. , Stephens D.J. , Lucovsky G. , Bachmann K.J. 
Published: March 2011

AbstractBrewster Angle Reflectance Differential Spectroscopy (BARDS) has been proposed as an optical method for real-time characterization of the growth of thin films. BARDS is based on changes in the reflectivity, Rp, of parallel (p)-polarized light incident at, or near, the Brewster angle of the substrate material. Changes in R are sufficiently large to monitor layer growth, and to determine the thickness and the optical constants of the deposited film. In this paper we extend the method to multilayer film deposition. The derivative properties of R are correlated with differences in the optical constants of the two materials, and with the sharpness of their interface. We present spectra for SiO2/Si3N4/SiO2/Si, demonstrating some of these aspects of this new and effective approach to in-situ monitoring.
Characterization of Cd1-x ZnxTe Alloys Using Infrared Reflectivity and Raman Scattering Spectroscopy
Authors: Talwar D. N. , Feng Z. C. , Becla P. 
Published: March 2011

AbstractStudy of impurity-induced phonon disordering in Cdl-xZnxTe alloys is reported for a variety of samples by using far-infrared reflectivity and Raman scattering spectroscopy. Substantial differences were noted among the various published values for the optical phonon frequencies versus x. Contrary to an earlier Raman study on MBE grown Cdl-xZnxTe/GaAs films, our results within a twomode behavior, yield an increase of both the CdTe- and ZnTe-like transverse optical phonons with x. Unlike earlier speculations for a gap-mode in ZnTe : Cd of ∼140∼145 cm−1, our Greens function theory predicts it to be at a relatively higher frequency of ∼153 cm−1.
Reactive Sputtiering in Oxidizing/Reducing Atmospheres
Authors: Klein J. D. , Yen A. , Clauson S. L. 
Published: March 2011

AbstractThe deposition of thin films by magnetron sputtering is readily influenced by the reduction/oxidation characteristics of the plasma. Unfortunately, the redox state of the sputter plasma is often inadvertently determined by uncontrolled factors such as transient evolution of species from the target. Undesirable variations in film and target properties can be avoided by actively setting the redox conditions. This is most readily accomplished by including two competing species, one oxidizing and the other reducing, in the chamber gas mixture. Optical emission spectroscopy, an in-situ process monitor, was employed to observe redox interactions in nominally unreactive dc sputtering of YBCO and reactive rf sputtering of IrO2. Optical spectroscopy of YBCO sputtering reveals that the intensity of atomic oxygen emissions decreases with H2 additions to the sputter gas blend.
Evaluation of Dry Etching Induced Damage of Gainas Using Transmission Lines and Schottky Diodes
Authors: Thomas S. , Pang S. W. 
Published: March 2011

AbstractPlasma etching of GaInAs and AlInAs has been carried out in a system which consists of an electron cyclotron resonance (ECR) source and an rf-powered stage. Since the ECR source can generate a plasma with low ion energy, dry etching induced damage is expected to be minimal. In this study, Schottky diodes and transmission lines were fabricated on the etched GaInAs surface. The diode and transmission line characteristics were evaluated as a function of etch conditions. For the etching of GaInAs and AllnAs, C12 and Ar were used as the etch gases. In addition to the ratio of the two gases, microwave power, rf power, pressure, and source distance were varied and their effects on etch rate, morphology, and surface damage were analyzed. Etch rate increased monotonically with microwave power, rf power, and C12 percentage. Etch rate decreased with increasing distance and reached a maximum for a pressure of 1 mTorr. The etch conditions for the damage study were chosen to maintain smooth morphology. One of the most important factors influencing damage was the ion energy which can be limited by using low rf power and short source distance. Minimum damage was obtained at 1 mTorr which provides the optimal balance between high etch rate and low ion energy. Besides limiting ion energy, the addition of Cl2 reduced etch-induced damage. The specific contact resistivity and sheet resistivity obtained from transmission line measurements of dryetched n-GaInAs were lower than the wet-etched samples. Schottky diode analysis show reduction in barrier height and breakdown voltage after Ar sputtering. Addition of 10% C12 is sufficient for full recovery of the diode characteristics.
Characterization of Cadmium Zinc Tellurium Obtained by Modified - Bridgman Technique
Authors: Acosta D.R. , Rabago F. 
Published: March 2011

AbstractThe growth of ternary semiconductor compounds Cd1-ZZnx. Te leads to possible uses of this material like optoelectronic devices. In the present work we report the structural characterization of Cd0.96Zn0.04Te obtained by modified - Bridgman technique. Structural studies were carried out using Scanning Electron Microscopy (SEM) and Conventional and High Resolution Electron Microscopy (TEM and HREM, respectively). Selected Area Electron Diffraction (SAED) was used to determine local variations in composition. Characteristics of the growth of the bulk samples were observed and structural details that might be related with the stability of ternary phase were derived.
In-Situ Dual-Wavelength Ellipsometry and Light Scattering Monitoring of Si/Si1−xGex Heterostructures and Multiuantum Wells
Authors: Pickering C. , Hope D.A.O. , Leong W.Y. , Robbins D.J. , Greef R. 
Published: March 2011

AbstractIn-situ dual-wavelength ellipsometry and laser light scattering have been used to monitor growth of Si/Si1−x,Gex heterojunction bipolar transistor and multi-quantum well (MQW) structures. The growth rate of B-doped Si0 8Ge0.2 has been shown to be linear, but that of As-doped Si is non-linear, decreasing with time. Refractive index data have been obtained at the growth temperature for x = 0.15, 0.20, 0.25. Interface regions ∼ 6-20Å thickness have been detected at hetero-interfaces and during interrupted alloy growth. Period-to-period repeatability of MQW structures has been shown to be ±lML.
Determination of BPSG Thin-Film Properties using IR Reflection Spectroscopy of Product Wafers
Authors: Niemczyk Thomas M. , Franke James E. , Zhang Lizhong , Haaland David M. , Radigan Kenneth J. 
Published: March 2011

AbstractThree BPSG calibration sets were analyzed using infrared external reflection-absorption spectroscopy: 1) 21 films deposited on undoped silicon coated with 0.1 pm of silicon dioxide, 2) 21 films deposited on undoped silicon, and 3) 9 films deposited on microelectronics product wafers. A multivariate partial least squares analysis of the spectral data for the first large data set showed that boron content, phosphorus content, and film thickness can be quantified with precisions of 0.10 wt%, 0.12 wt%, and 30 Å, respectively. The second large data set yielded similar results. The precisions obtained for the nine product wafer samples were 0.13 wt% B, 0.09 wt% P, and for film thickness 103 Å.
Deep Level Defects, Luminescence, and the Electro-Optic Properties of SiGe/Si Heterostructures
Authors: Bhattaci-Iarya Pallab , Li Shin-Hwa , Lee Jinju , Smith Steve 
Published: March 2011

AbstractDeep levels and luminescence in SiGe/Si heterostructures and quantum wells have been investigated. We have studied the effects of Be- and B-doping on the luminescent properties of Si1−xGex/Si single and multiquantum wells. No new levels, or enhancement of luminescence, from that in undoped samples, is detected in samples which are selectively doped in the well-regions, implying that the observed luminescence in the undoped quantum wells is a result of alloy disordering. Slight enhancement of luminescence is observed in disordered wells and in quantum wires made by electron beam lithography and dry etching. Deep levels have been identified and characterized in undoped Si1-xGex alloys. Hole traps in the p-type layers have activation energies ranging from 0.029-0.45 eV and capture cross sections (σ∞) ranging from 10−9 to 10−20 cm2. Possible origins of these centers are discussed. Some possibilities of obtaining enhanced electro-optic coefficients in SiGe/Si heterostructures are discussed.
Contact-Related Deep States in AI-GaInP/GaAs Interface
Authors: Huang Z.C. , Wie C.R. 
Published: March 2011

AbstractDeep levels have been measured in molecular beam epitaxy grown Ga0.51In0.49P/GaAs heterostructure by double correlation deep level transient spectroscopy. Gold(Au) and Aluminum (Al) metals were used for Schottky contact. A contact-related hole trap with an activation energy of 0.50-0.75eV was observed at the A1/GaInP interface, but not at the Au/GaInP interface. To our knowledge, this contact-related trap has not been reported before. We attribute this trap to the oxygen contamination, or a vacancy-related defect, VIn or VGa. A new electron trap at 0.28eV was also observed in both Au- and Al-Schottky diodes. Its depth profile showed that it is a bulk trap in GaInP epilayer. The temperature dependent current-voltage characteristics (I-V-T) show a large interface recombination current at the GaInP surface due to the Al-contact. Concentration of the interface trap and the magnitude of recombination current are both reduced by a rapid thermal annealing at/or above 450°C after the aluminum deposition.
Hydrogen Passivated Carbon Acceptors in GaAs and AlAs: no Evidence for Carbon Donors
Authors: Davidson B. R. , Newman R. C. , Pritchard R. E. , Bullough T. J. , Joyce T. B. , Jones R. , Öberg S. 
Published: March 2011

AbstractGaAs and AlAs layers grown by CBE and doped with either 12C or 13C have been passivated with hydrogen or deuterium. Infrared absorption lines due to hydrogen stretch modes, symmetric A1 modes and “carbon-like” E modes of H-CAs and D-CAs pairs have been assigned for both isotopes in both hosts. Comparisons have been made with new ab initio local density functional theory and simple harmonic models. Anticrossing behaviour is found for the two types of coupled E modes in the two hosts. The dynamics of the H-CAs centre are very similar in GaAs and AlAs.
Effects of Ion-Irradiation and Hydrogenation on the Doping of InGaAIN Alloys
Authors: Pearton S. J. , Abernathy C. R. , Hobson W. S. , Ren F. 
Published: March 2011

AbstractCarrier concentrations in doped InN, In0.37 Ga0.63 N and In0.75 Al0.25 N layers are reduced by both F+ ion implantation to produce resistive material for device isolation, and by exposure to a hydrogen plasma. In the former case, post-implant annealing at 450–500°C produces sheet resistances > 106 Ω/ℹ in initially n+ (7 x 1018 − 3 x 1019 cm−3) ternary layers and values of ∼5 x 103 Ω/ℹ in initially degenerately-doped (4 x 1020 cm−3) InN. The evolution of sheet resistance with post-implant annealing temperature is consistent with the introduction of deep acceptor states by the ion bombardment, and the subsequent removal of these states at temperatures −500°C where the initial carrier concentrations are restored. Hydrogenation of the nitrides at 200°C reduces the n-type doping levels by 1-2 orders of magnitude and suggests that unintentional carrier passivation occurring during cool down after epitaxial growth may play a role in determining the apparent doping efficiency in these materials.
Deep Level Structure of Semi-Insulating Movpe Gaas Grown by Controlled Oxygen Incorporation
Authors: Huang J. W. , Kuech T. F. 
Published: March 2011

AbstractSemi-insulating oxygen-doped GaAs layers have been grown by low pressure metalorganic vapor phase epitaxy (MOVPE) using aluminum-oxygen bonding based precursor diethyl aluminum ethoxide (DEALO). Resistivities of more than 2x109 Ω-cm at 294 K have been achieved. Deep level structure responsible for the high resistivity was investigated by deep level transient spectroscopy (DLTS) using DEALO and disilane co-doped GaAs p+-n homojunction. Multiple deep level peaks were observed, and the relative peak heights were found to vary with the dopant concentrations. Major deep levels were electron traps with ionization energy between 0.75 and 0.95 eV below conduction band edge minimum. An activation energy of 0.81 eV was deduced from temperature-dependent resistivity measurement, and should be closely related to the major0.75 eV peak in DLTS spectra.