bluuebunny/crossref_metadata_2025_split huggingface dataset:
Compositional Ordering in GalnP for Heterostructure Formation
Authors: Stringfellow G. B. , Su L. C. , Murata H. , Chun Y. S. , Ho I. H. , Hsu T. C. , Hosokawa Y. 
Published: April 2011

AbstractCompositional ordering is observed in essentially all IIIN semiconductor alloys. The mechanism leading to the specific ordered structures formed is only now beginning to be understood. It is intimately related to the atomic-scale physical processes occurring on the surface during epitaxial growth, specifically surface reconstruction and the attachment of atoms at steps. This paper will emphasize the use of surface analytic techniques to better understand the ordering processes during organometallic vapor phase epitaxial growth of GalnP. Surface photo absorption has been used to determine, for the first time, that the surface reconstruction is (2×4)-like during growth of GalnP with Cu-Pt ordering. By increasing the growth temperature and/or decreasing the V/Ill ratio the concentration of phosphorus dimers characteristic of the (2×4) structure is observed to decrease in tandem with a decrease in the degree of order measured in the epitaxial layers. This suggests that formation of the (2×4) reconstruction is necessary for formation of the Cu-Pt ordered structure.Atomic force microscopy was used to examine the step structure. For exactly (001)-oriented substrates, growth at low V/Ill ratios produces islands surrounded by single monolayer steps. Increasing the V/Ill ratio leads to the formation of bilayer steps approximately 6 Å high. A similar change in the structure of steps is observed in the vicinal regions for substrates misoriented to produce [110] steps. This phenomenon is interpreted in terms of the stabilization, at high V/Ill ratios, of the (2×2) reconstruction on the (111)B regions of the bilayer steps. This may also have an effect on formation of the Cu-Pt ordered structure.By changing the substrate temperature or the input partial pressure of the phosphorus precursor, the degree of order and, hence, the bandgap energy of GalnP, can be modulated during growth. This has allowed the production of a variety of single and double heterostructures. The heterostructures produced by changing the temperature from 740 to 620°C and from 620 to 520°C are abrupt. The heterostructures formed by changing the phosphine flow rate are not. The ordered structure in the lower layer persists into the upper layer. This may be an indication of the importance of the step structure.
Structural Characterization of Composition-Modulated ZnSel-xTex Epitaxial Films
Authors: Ahrenkiel S. P. , Bode M. H. , Al-Jassim M. M. , Luo H. , Xin S. H. , Furdyna J. K. 
Published: April 2011

AbstractWe examine the microstructure of short-period (14–31 Å) composition modulations in epitaxial ZnSel-xTex (x@0.5) films grown by molecular-beam epitaxy (MBE) on vicinal (001) GaAs. Transmission electron microscope (TEM) images of cross-sections reveal highly-periodic contrast along the growth direction throughout the full thicknesses of the films (over 2 μm) that corresponds to a nearly sinusoidal variation between Se- and Te-rich compositions. Growth of ZnSe1-xTex at 285°C on substrates tilted 4° toward [1111 maximizes the strength and regularity of the modulation. Using dynamical electron-diffraction simulations, we estimate a modulation amplitude of r@0.184(7) in a sample showing strong modulation. We assume a small amplitude of strain modulation to fit the experimental data.
The Formation of Radiative Defects at GaAs/GaInP Interface
Authors: Uchida Kazuo , Arai Takayuki , Matsumoto Koh 
Published: April 2011

AbstractWe report the optical characteristics of 100 A˚ thick GaAs/Ga0.521n0.48P single quantum wells grown by Metal Organic Vapor Phase Epitaxy. We have confirmed from the 77 K photoluminescence (PL) that an optimum growth sequence is necessary to achieve the emission from the well (1.52 eV), otherwise only the deep emission band (1.46 eV) is observed. From the time-resolved photoluminescence and temperature dependent PL measurements, we assign that this 1.46 eV deep emission is a recombination of electron-hole pair in a vacancy-related defect which is spatially distributed at the imperfect GaAs/Ga 0.521n0.48P interface.
Mechanisms of Thin Film Ti And Co Silicide Phase Formation on Deep-Sub-Micron Geometries and Their Implications and Applications To 0.18 °m CMOS and Beyond
Authors: Kittl J. A. , Hong Q. Z. , Rodder M. 
Published: April 2011

AbstractWe studied the kinetics of the high resistivity to low resistivity phase transformation for Ti and Co silicides on deep-sub-micron geometries. Fundamental differences between the growth characteristics for Co and Ti result in different scaling behavior. While the the TiSi2 C54 phase grows by a random nucleation and growth process from the polymorphic TiSi2 C49 phase, CoSi 2 grows by a diffusion limited process from CoSi. A strong linewidth and C49 grain size dependence for the TiSi2 C49 to C54 transformation can be related to low nucleation density. A Johnson-Mehl-Avrami analysis was performed for the TiSi2 C49 to C54 transformation obtaining the distribution of Avrami exponents and transformation times for individual 0.26 μm lines, showing that all lines transformed with similar one-dimensional growth characteristics. We found a strong dependence of the half-transformation times on film thickness and linewidth. While activation energies depend strongly on film thickness, ranging from 4.2 to 5 eV for films 64 to 28 nm thick, they are insensitive to linewidth indicating a different nature for the effect of linewidth and thickness. We also found a reduction of agglomeration temperatures with decreasing linewidth or film thickness resulting on a narrower process window for deep-submicron devices. A small linewidth dependence was measured for CoSi to CoSi2 transformation rates, with activation energies of 2 to 2.2 eV for 0.27 μm and wider lines. Both Co and Ti selfaligned silicide processes were implemented successfully into a 0.18 μm technology.
Mesostructured Zirconium Oxide
Authors: Liu P. , Reddy J. S. , Adnot A. , Sayari A. 
Published: April 2011

AbstractThe supramolecular templating technique was used to synthesize both hexagonal (Hx- ZrO2) and lamellar (L-ZrO2) phases of zirconium oxide. Under the conditions used in this work, the use of long chain primary amines and quaternary ammonium surfactants resulted in the exclusive formation of lamellar and hexagonal phases, respectively. The use of long chain cetyldimethylamine afforded a mixture of a hexagonal and a lamellar phases. Effects of synthesis parameters such as the ZrO2/surfactant ratio, ZrO2/water ratio, the nature of surfactant, the crystallization temperature and time on the formation of mesostructured ZrO2 were also studied. Addition of 1,3,5-trimethylbenzene (TMB) as a swelling agent led, in the presence of cetyltrimethylammonium bromide, to the formation of a lamellar phase rather than to pore enlargement. These materials were characterized by XRD, FTIR, XPS and EDX techniques. Regardless of their structure, the as-synthesized materials collapsed upon calcination. Treatment with monobasic potassium phosphate followed by calcination at 350 °C led to the formation of a stable porous Zr–P oxide with a surface area as high as 540 m2/g.
Porous Silica Doping by Ion Bombardment
Authors: Cerofolini G. F. , Meda L. , Anselmino A. , Ranghino G. 
Published: April 2011

AbstractA new approach to porous-silica doping is via ion bombardment and exposure of thedamaged structure to a controlled atmosphere. As a case study, SiO2 samples, bombarded with Ar2+ in a CO2 ambient and suitably processed, underwent an infrared spectroscopic investigation. The resulting data could be interpreted by assuming the addition of CO2 to the SiO2 skeleton at the diradical silicon defects produced by the bombardment. This addition takes place first via the formation of a carboxylate group, which evolves after heattreatment to an ester-like center, and eventually to a carboxilic acid after exposure to water vapour. Ab initio molecular-dynamics simulations of the interaction between CO2 and a silicon diradical are consistent with the above picture and suggest also the existence of anintermediate, in which tetrahedral carbon is bonded to the two silicon atoms and to two oxygen atoms.
Microporous Crosslinked Elastomers
Authors: Hedrick J. L. , Srinivasan S. , Miller R. D. , Shih D. Y. , Liao Y.-H. , Hilborn J. G. , Plummer C. J. G. , Martina A. Della 
Published: April 2011

AbstractElastomeric connectors have been developed for a wide variety of interconnection and test applications which include module-to-board, board-to-board interconnections, high density module, board and LCD testings, as well as chip/wafer testing and burn-in to produce known-good-die. The density, compliance, thickness, pattern and size of these structures can be tailored to meet the requirements of each application. The fabrication processes involve wire bonding and polymer encapsulation. To achieve high compliance with low contact force, alternative means of generating highly compliant elastomers has been developed. This approach involves the incorporation of voids, where the reduction in the compressive force is simply achieved by replacing a portion of the polymer with air. Two approaches of generating porous elastomers are described along with the details of the porosity and mechanical properties.
A Review of the Aqueous Chemistry of the Zirconium - Water System to 200°C
Authors: Adair James.H. , Krarup Henrik G. , Venigalla Sridhar , Tsukada Takayuki 
Published: April 2011

AbstractThe aqueous chemistry of the Zr-H2O system is reviewed. It is shown that the thermodynamically stable solid phase for the Zr-H2O system at 25°C is the monoclinic phase. After a review of the chemistry of the pure material in water, a summary of the solution equilibria of the Zr-H2O system is presented followed by a discussion of the aqueous phase stability of the monoclinic and tetragonal phases of the pure ZrO2 system. Last, a discussion of the phase stability of the complex metal oxides, particularly the Y2O3-containing TZP in aqueous solution will be reviewed. It will be shown that the phase stability for the complex metal oxide-zirconia systems may be best understood as corrosion with the alloying agent (e.g., Y2O3) subject to leaching from a zirconia-rich interface.
Ion Exchange Properties of Novel Hydrous Metal Oxide Materials
Authors: Gardner T. J. , McLaughlin L. I. 
Published: April 2011

AbstractHydrous metal oxide (HMO) materials are inorganic ion exchangers which have many desirable characteristics for catalyst support applications, including high cation exchange capacity, anion exchange capability, high surface area, ease of adjustment of acidity and basicity, bulk or thin film preparation, and similar chemistry for preparation of various transition metal oxides. Cation exchange capacity is engineered into these materials through the uniform incorporation of alkali cations via manipulation of alkoxide chemistry. Specific examples of the effects of Na stoichiometry and the addition of SiO2 to hydrous titanium oxide (HTO) on ion exchange behavior will be given. Acid titration and cationic metal precursor complex exchange will be used to characterize the ion exchange behavior of these novel materials.
A Glass Durability Model Based on Understanding Glass Chemistry and Structural Configurations of the Glass Constituents
Authors: Feng Xiangdong , Metzger Todd B. 
Published: April 2011

AbstractAn improved structural bond strength (SBS) model has been developed to quantify the correlation between glass compositions and their chemical durabilities. The SBS model assumes that the strengths of the bonds between cations and oxygens and the structural roles of the individual elements in the glass are the predominant factors controlling the composition dependence of the chemical durability of glasses. The structural roles of oxides in glass are classified as network formers, network breakers, and intermediates. The structural roles of the oxides depend on glass composition and the redox state of oxides. A12O3, ZrO2, Fe2O3, and B2O2 are assigned as network formers only when there are sufficient alkalis to bind with these oxides. CaO can also improve durability by sharing non-bridging oxygen with alkalis, relieving Si0 2 from alkalis. The binding order to alkalis is AI2O3>ZrO2>Fe2O 2>B2O2>CaO>SiO2. The percolation phenomenon in glass is also taken into account. The concentration of network formers has to reach a critical value for a glass to become durable; durable glasses are sufficient in network formers and have a complete network structure; poor durability glasses are deficient in network formers and the network is incomplete and discontinuous. The SBS model is capable of correlating the 7-day product consistency test durability of 42 low-level waste glasses with their composition with an R2 of 0.87, which is better than 0.81 obtained with an eight-coefficient empirical first-order mixture model on the same data set.
In Situ Infrared Study of Chemical Nature of Si Surface in Etching Solution and Water
Authors: Niwano Michio , Miura Taka-Aki , Kimura Yasuo , Tajima Ryo 
Published: April 2011

AbstractThe chemical nature of Si(100) and (111) surfaces during immersion in dilute hydrofluoric acid (HF) solution and water was investigated “in-situ” and in real time using infrared absorption spectroscopy in the multiple internal reflection geometry. We demonstrate that in dilute HF solution, Si surfaces are not perfectly terminated by hydrogen, but are covered in part with hydrogen-associated Si fluorides, such as SiH2(SiF). We find that the hydrogen coverage of the surface during storage in dilute HF solution depends on the HF concentration of the solution. It is shown that rinsing in water following HF treatment leads to complete hydrogen termination of the surface. We also show that hydrogen exchange reaction occurs on the hydrogen-terminated Si surface during storage in water.
X-Ray Texture Analysis of Oriented PZT Thin Films
Authors: Peterson C. R. , Medendorp N. W. , Slamovich E. B. , Bowman K. J. 
Published: April 2011

AbstractPZT thin films with the composition Pb(Zr0.6Ti0 4)O3 were processed via metallo-organic decomposition (MOD) with {111} and {100} orientations. Ferroelectric measurements showed that the {111} and {100} oriented films had remanent polarizations of 19.5 μC/cm2 and 16 μC/cm2, respectively. Both x-ray pole figure analysis and the Harris texture index were used to quantify the degree of {100}, {110}, and {111} orientation in each film, with reasonable agreement between the two methods. The {100} oriented thin film was determined to be 582 times random for the Harris technique versus 522 times random for pole figure analysis, while the {111} oriented film was 41 times random for the Harris technique and 81 times random for pole figure analysis. The axisymmetric texture of the films allow 2-D pole figure analysis to provide a quantitative characterization of film texture.
Effect of Rapid Thermal Processing on the Crystallization Properties of PbTiO3 Ferroelectric Thin Film
Authors: Zhu Jianguo , Chen Meng , Peng Wenbing , Lan Fahua , Sviridov E.V. , Iao Dingquan 
Published: April 2011

AbstractThe fabrication methods of ferroelectric (FE) thin films have received special attention in recent years because of the needs of FE thin films integrated with semiconductor devices. Rapid thermal processing (RTP) has developed in fabrication of FE thin films because it can reduce processing temperature and time duration, and it also improves the properties of FE thin films compatible with semiconductor devices. The thin film samples used were prepared by a multi-ion-beam reactive cosputtering system (MIBRECS) at room temperature. The samples were then subjected to a post-deposition annealing in a RTP system. It was found that PbTiO3 (PT) thin film could grow on amorphous or polycrystal interfacial layer and the PT thin films annealed by RTP showed the prefered [110] and [100] textures. The effect of interfacial layer on the crystallization and microstructure of the films was also discussed.
Micromechanics of Deformation and Fracture in Low Symmetry Layered Materials
Authors: Kad Bimal K. , Dao Ming , Asaro Robert J. 
Published: April 2011

AbstractDeformation microstructures in γ-TiAl + α2Ti3Al based low symmetry layered materials, with fully lamellar (FL) microstructures, have been simulated using micro-mechanical methods. In this particular effort we embed the specific contributions of scale and temperature dependent plastic anisotropies of individual colonies of Poly Synthetically Twinned (PST) lamellar TiAl and demonstrate their effect on overall defonnation and fracture response.
Coherency Strain and High Strength at High Temperature
Authors: Brenchley M. E. , Dunstan D. J. , Kidd P. , Kelly A. 
Published: April 2011

AbstractWe propose an athermal strengthening mechanism for high-temperature structural materials in which large coherency strains are built in to a layered structure in order to prevent dislocation mulitplication mechanism from functioning. A practical model system is provided by semiconductor strained-layer superlattices of InGaAs grown on InP. We report results from highresolution X-ray diffraction and from direct tensile testing which provide evidence for athermal strengthening. A discussion of methods of micro-mechanical testing is also included.
Effects of Mechanical Properties of Metal Films on The Adhesion Strength of Cr/Polyimide Interfaces
Authors: Choi Jin Won , Oh Tae Sung 
Published: April 2011

AbstractEffects of mechanical properties of Cu/Cr metal films on the peel strength of Cr/PI interfaces have been studied. Cr and Cu thin films were successively sputter-deposited on in-situ RF plasma-treated polyimides, and 20 μm-thick Cu was electroplated. With increasing the yield strength of Cu/Cr films from 156 MPa to 325 MPa, peel strength of Cr/PMDA-ODA and Cr/BPDA-PDA were lowered from 75 g/mam to 57 g/mm and from 69 g/mm to 20 g/mm, respectively. With identical Cu/Cr metal films, lower peel strength was obtained on Cr/BPDA-PDA interfaces, compared to the values of Cr/PMDA-ODA. Peel strength was also decreased more pronouncedly on Cr/BPDA-PDA with increasing the yield strength of Cu/Cr metal films. With T/H (80°C/94% R.H.) exposure, however, peel strength was lowered much more pronouncedly on Cr/PMDA-ODA than on Cr/BPDA-PDA, especially for specimens with Cu/Cr metal films of lower yield strength.
Inaccuracies in Sneddon's Solution for Elastic Indentation by a Rigid Cone and their Implications for Nanoindentation Data Analysis
Authors: Bolshakov A. , Pharr G. M. 
Published: April 2011

AbstractMethods currently used for analyzing nanoindentation load-displacement data to determine a material's hardness and elastic modulus are based on Sneddon's solution for the indentation of an elastic half-space by a rigid axisymmetric indenter. Although this solution is widely used, no attempts have been made to determine how well it works for conditions of finite deformation, as is the case in most nanoindentation experiments with sharp indenters. Analytical and finite element results are presented which show that corrections to Sneddon's solution are needed if it is to be accurately applied to the case of deformation by a rigid cone. Failure to make the corrections results in an underestimation of the load and contact stiffness and an overestimation of the elastic modulus, with the magnitude of the errors depending on the angle of the indenter and Poisson's ratio of the half-space. For a rigid conical indenter with a half-included tip angle of 70.3°, i.e., the angle giving the same area-to-depth ratio as the Berkovich indenter used commonly in nanoindentation experiments, the underestimation of the load and contact stiffness and overestimation of the elastic modulus may be as large as 13%. It is shown that a simple first order correction can be achieved by redefining the effective angle of the indenter in terms of the elastic constants. Implications for the interpretation of nanoindentation data are discussed.
Nano Scale Creep and the Role of Defects
Authors: Asif S. A. Syed , Pethica J. B. 
Published: April 2011

AbstractThe modulating force method in nanoindentation gives a direct measure of contact stiffness, and being insensitive to drift, allows the accurate observation of creep in small indents to be carried out over long time periods. We present results for a range of metals at room temperature. Strain rate indices similar to those for macroscopic creep are found. Reverse creep occurs for step unloading greater than about half the starting load. For electropolished tungsten, we find quite different behaviour before and after the sudden pop-in. Afterwards, creep is as in other metals, but beforehand, it is essentially zero. The slight changes of stiffness observed at the very smallest loads are due to diffusion of adsorbed surface films into the contact zone. Our results show that the dislocations nucleated and multiplied at pop-in provide the mechanism of creep.
Nonlinear Acoustic Response in thin Oxide Layers on Fused Silica
Authors: Ottermann C. R. , Fassbender S. U. , Arnold W. , Bange K. 
Published: April 2011

AbstractNonlinear mechanical properties of layered systems of Ta2O5 and TiO2 films deposited on fused silica by reactive evaporation (RE), reactive ion plating (IP) and spin coating (SC) are investigated by means of an ultrasonic technique. The coatings with thickness of 100 nm possess differences in density and crystal structure, due to the different deposition conditions. The nonlinear acoustic response of the film/substrate systems depends on film material. Differences are observed in respect to film density as obtained by the alternate deposition methods. The origin of the differences in nonlinear acoustic response of the samples is discussed. The results are correlated to adhesion properties of the films determined by a scratch-test method.
Measurement of Low-k Polymerimetal Interfacial Toughness Using 4-point Bending Method
Authors: Ma Qing , Pan Chuanbin , Fujimoto Harry , Triplett Baylor , Coon Peter , Chiang Chien 
Published: April 2011

AbstractFour-point bending method offers significant advantages over more traditional techniques in measuring adhesion properties of thin polymer films. The former utilizes sandwich structure beams where the polymer film and the interface of interest are placed at the center of two elastic bulks. Such confined geometry closely resembles applications where polymer films are used as dielectric layers in IC interconnect technology. In this work, the bonding between a poly(arylene ether) (PAE) based polymer film and an Al film was studied. Ti layers of several different thickness were used as adhesion promoter. The sandwich samples were made by bonding bulk wafers using an epoxy. Fracture energies were seen to increase with the thickness of the Ti layer. Effects of heat treatment were also studied.