bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microstructure of Buried Thin Etch Stop Films Formed by Nitrogen Implantation into Silicon
Authors: Romano-Rodriguez A. , El-Hassani A. , Perez-Rodriguez A. , Samitier J. , Morante J.R. , Esteve J. , Acero M.C. 
Published: March 2011

ABSTRACTThe microstructure of buried layers obtained by medium to high dose nitrogen ion implantation in silicon for etch-stop applications is investigated as a function of the implantation conditions (dose and temperature). Samples are analyzed by TEM, SIMS, FTIR and XPS measurements. The correlation between the data from the different techniques allows to characterize the different layers in the structure, determining the phases induced during the process, the crystalline nature of the layers and the presence of structural defects. The obtained data show the gettering of nitrogen after annealing in both a buried layer around the implantation peak and in the surface region. The nitrogen concentration in these regions and the formation and nature of silicon nitride precipitates show strong dependences with the implantation dose and temperature.
Continuum Modeling of Stress-Driven Surface Diffusion in Strained Elastic Materials
Authors: Freund L. B. , Beltz G.E. , Jonsdottir F. 
Published: March 2011

ABSTRACTThe free energy of a deformable crystal is assumed to consist of elastic strain energy and surface energy, and the chemical potential for surface diffusion at constant temperature is obtained under this assumption. The result is applied in considering the phenomena of instability of a flat surface in a stressed material under fluctuations in surface shape, and the development of surface roughness due to the proximity of misfit dislocations to the free surface of the material.
A Misfit Dislocation Blocking Mechanism in Continuous InGaAs Layers Grown on Patterned GaAs
Authors: Patrick Watson G. , Ast Dieter G. , Anderson Timothy J. , Pathangey Balu 
Published: March 2011

ABSTRACTPrevious work showed that misfit dislocations were blocked at trench walls in a unique way in InGaAs strained layers grown on GaAs that was patterned and etched to form a series of mesas separated by trenches. A model is developed to explain the behavior of misfit dislocations in this material. The energy cost of extending the threading dislocation segment, which accompanies a misfit dislocation during glide, can impede the motion of these defects if the trench walls are steep enough.
Stress Dependence of the Velocity of Threading Dislocation Segments in Si - Ge Heteroepggaxial Films.
Authors: Gillard Veronique T. , Noble David B. , Nix William D. 
Published: March 2011

ABSTRACTThis paper presents data for threading dislocation velocities measured in Si-Ge heteroepitaxial thin films during in situ HVTEM annealing experiments. These data are compared to three models which were previously developed to describe the kink mode of dislocation motion. Two of these models, Hirth and Lothe [1] and Seeger-Schiller [2], are based on the discrete narrow kink representation. The other, developed by Büttiker and Landauer [3], is based on the macroscopic bulge model representation of the dislocation line. It is found that both the narrow kink models underestimate dislocation velocities in the stress range of the experiments and that a good representation of the data can be obtained by using the macroscopic bulge model in the dislocation length-dependent regime.
The Effect of Cold-Working on the Crystallization Temperature of Thin-Film Shape Memory Effect TiNi.
Authors: Madsen John S. , Jardine A. Peter 
Published: March 2011

ABSTRACTThe minimum temperature for the crystallization of amorphous TiNi on substrates is of interest in developing thin-film SME material while minimizing chemical interactions with the substrate. Using 20 micron thick free standing TiNi material annealed in a vacuum furnace, X-Ray diffraction of the thin-films indicated that the crystallization occured within 20 minutes at 510°C, 490°C and 480°C. At 450°C, crystallization kinetics were significantly slower, and the foils were fulling crystallized after annealing for 7.5 hrs. To further lower the crystallization temperature, cold working of the foil by rolling was introduced and full crystallization was observed after 7.5 hours annealing at 400°C in a cold-worked foil. Cold working and annealing at 400°C and 350°C for 7.5 hrs did not observably promote lower crystallization temperatures.
Strain-Induced Reconstruction of Impurity States in PbTe(Ga) Films
Authors: Akimov Boris A. , Ryabova Ludmila I. , Slynko Evgeniy I. 
Published: March 2011

ABSTRACTn-type PbTe(Ga) films were grown by the laser deposition and the hot wall techniques on BaF2 substrates in <111> orientation. Doping results in the appearance of a high-ohmic state with nearly intrinsic free carrier concentration at low temperatures and activation character of conductivity at T∼300 K. Persistent photoconductivity has been observed at T < 100 K. In the hot wall-grown layers a new effect of bistability during the cooling-heating-cooling cycles has been found. On the first stage of the cycle a rapid decrease of resistivity (∼3 orders of magnitude) is observed at To∼50 K. The value of To changes by ± 15 K depending on the cooling rate. After a brief heating up to 80 K the subsequent cooling results in the high-ohmic state of the layer at the low temperatures. This state seems to be unstable. Relaxation to the low ohmic state can be accelerated by the application of electric field. The effect may be understood in terms of bistability of the Ga impurity charge state under the action of strain between the film and the substrate during the cooling-down process.
Structure Development in Polyimide Films
Authors: Coburn John C. , Pottiger Michael T. , Pryde Coralie A. 
Published: March 2011

ABSTRACTThe influence of processing conditions on the structure and properties in spin coated polyimide films prepared from flexible, semi-rigid and rigid chemistries was investigated. While the relationship between processing, structure and properties is different for each chemistry, some general trends were observed. Curing above the glass transition in the flexible polyimide BTDA//ODA/MPD, that is incapable of crystallizing and has very little in-plane orientation, has virtually no effect on the structure or properties compared to curing below the glass transition. Curing at temperatures above the glass transition in cry stall izable stiff polyimides such as BPDA//PPD and PMDA//ODA results in an increase in birefringence, in-plane CTE and biaxial stress. In BPDA//PPD, the increase in birefringence is attributed to an increase in polarizability and possibly, an increase in the overall in-plane alignment of the imide ring as evidenced by IR analysis. The increase in in-plane CTE is attributed to a loss in chain axis orientation caused by relaxation effects. The increase in stress is attributed to the increase in the in-plane CTE and also from shrinkage forces arising from crystallization. Rapid heating during cure in the flexible amorphous BTDA//ODA/MPD has essentially no effect on structure or properties compared to slow heating. In the semi-crystalline polyimides, rapid heating during cure leads to higher levels of crystallinity and significantly higher stresses. The increase in stresses is attributed to a loss in chain axis orientation in the plane of the film and shrinkage forces arising from additional crystallization. The directional dependence of the coefficient of thermal expansion, an important functional property, is extremely sensitive to molecular anisotropy. BTDA//ODA/MPD, which is almost isotropic, has an out-of-plane CTE that is approximately 20 percent higher than the in-plane CTE. In contrast, the out-of-plane CTE for the most anisotropic polyimide in this study, BPDA//PPD, is 25 times larger than the in-plane CTE. This sensitivity of the CTE to molecular orientation must be taken into account when modeling stress in, or designing, electronic devices.
Microindentation on Gelatin Films with a Spherical Indenter -- A Viscoelastic Analysis
Authors: Ni Beta Y. , Bisson Gary R. , Tsou Andy H. 
Published: March 2011

ABSTRACTA finite element model was employed to analyze the microindentation test with a spherical indenter on gelatin films. The deficiency of using elastic-plastic constitutive law to describe indentation response of gelatin film was recognized and a viscoelastic model was proposed for the first time to analyze indentation experiments on polymeric materials. Based on viscoelastic analysis, it was found that gelatin is nonlinear viscoelastic. In addition, modulus in the thickness direction of a gelatin film was determined to be 2.5–2.9 GPa as compared with its tensile modulus of 4.6 GPa in the transverse direction.
Growth Mechanism, Local Stresses, and Young's Moduli of Micro-Deformation Zones in Glassy Polymers Films by AFM
Authors: Yang A.C.-M. , Kunz M.S. , Wu T.W. 
Published: March 2011

ABSTRACTBy studying the topography of crazes and shear deformation zones in polymer films with the Atomic Force Microscope (AFM), it was found that crazes and shear deformation zones grew by a micro-necking process. This discovery indicates that when a glassy polymer undergoes local deformations, the material drawn into the deformation zones continues to be deformed until a much later time than that previously understood. Details of the craze micro-necking mechanism and its important implications will be discussed. Based on the necking mechanics, it was shown that craze initiation and growth can be examined using a modified Considere construction, and the stress distribution within a micro-deformation zone was investigated by assuming the Bridgman's theory. The results of the stress analysis are in excellent agreement with the breakdown behavior of crazes observed experimentally. The Young's moduli of the crazed and sheared polymers within the tiny deformation zones were also measured using a simple new AFM technique. Evidence of strain softening was clearly observed in that both the Young's moduli of crazes and shear deformation zones were very low compared to that in the bulk.
Studies of Sputter Deposited CU1-XTAX Alloys
Authors: Wang Hong , Zaluzec M. J. , Liu Y. , Mazumder J. , Rigsbee J. M. 
Published: March 2011

ABSTRACTCopper-refractory metal composites/alloys are of interest for aerospace and related applications requiring good thermal conductivity and high strength at elevated temperatures[1]. These materials, due to generally very low mutual solubilities, may allow high strength microstructures to be developed which are stable at temperatures exceeding those suitable for precipitation strengthened alloys. Phase stability and mechanical property characteristics of bulk fabricated Cu-refractory metal composites were recently reviewed[2-3]. This paper reports the results of structure-property studies of a series of Cu1–xTax alloys created by RF sputter deposition. It will be shown that nanoscale face-centered-cubic and body-centered-cubic Ta particles form in the Cu matrix and that these Ta particles are very resistant to coarsening at temperatures up to 900ºC. Nanoindentation studies of these alloys reveal that their strengths are also essentially unaffected by exposure to 900ºC for times up to 100 hours.
Mechanical Testing in Electroless Ni Modified TiN Coating
Authors: Duh J. G. , Doong J. C. , Huang C. T. 
Published: March 2011

ABSTRACTTiN films are prepared by reactive rf magnetron sputtering on carbon steel substrates which are widely applied as structural materials. The electroless Ni-P plating is introduced as an interlayer in the surface modification of TiN coating. The electroless Ni-P deposit crystallizes during rf sputtering due to the elevated sputtering temperature and thus a TiN/Ni3P/Fe coating assembly is formed.The employment of electroless Ni-P deposit results in an increase in the surface microhardness and adhesion strength. The surface hardness as high as 2266HK1 close to the hardness of bulk TiN can be achieved in the Ni3P interlayer modified TiN coating. With respect to the wear-resistance, the adhesion of the TiN coating plays an important role for the sliding wear-resistance and the interlayer Ni3P acts as a hard , barrier instead of the soft carbon steel substrate.
Stress, Mechanical Properties and Composition Measurements in Sputtered Thick Alumina Films
Authors: Ross C. A. , Barrese J. J. 
Published: March 2011

ABSTRACTThick r.f.-sputtered alumina is used as an overcoat material in microelectronic applications. The stress in the material is compressive and its magnitude is influenced by the sputtering conditions including the power, gas pressure and r.f. substrate bias. These parameters also affect the deposition rate, stoichiometry and sputter gas (argon) content of the material and its etch rate in hydroxide solutions. Nanoindentation measurements of the elastic modulus and hardness are presented for alumina sputtered under different bias conditions and show that the zero bias material appears to be harder and suffer than material deposited at -100V bias.
Micromechanical Characterization of Dielectric Thin Films
Authors: Grow James M. 
Published: March 2011

ABSTRACTA nanoindenter has been used to obtain Young's modulus and hardness data for a variety of dielectric thin films including silicon carbide, boron nitride, silicon carbonitride, and silicon oxide. These films, were synthesized by low pressure and plasma enhanced chemical vapor deposition, and had a thickness from 0.25 to a few microns. For the BN films, the modulus and hardness of the films decreased significantly as the deposition temperature increased while the reverse was true for the SiC films. In both cases, these changes were related to variations in the compositions of the deposits due to the onset of different reactions as the temperature is increased. Silicon carbonitride films oxidized slowly when synthesized at temperatures below 200º C and the Young's modulus of these films increased at higher deposition temperatures. For silicon dioxide, there was little change in the composition of the films over the deposition temperature range investigated (375–475º C), thus correspondingly, small variations in the micromechanical properties of the material. However, moisture and hydrogen removal caused by an anneal at 800º C resulted in an significant increase in the modulus and hardness of these films.
Adhesion in Metal-Ceramic Systems
Authors: Venkataraman Shankar K. , Gerberich William W. , Kohlstedt David L. 
Published: March 2011

ABSTRACTThe adhesion of Pt thin films to NiO substrates has been studied using the continuous microscratch technique. Films of Pt ranging from 65 to 1080 nm in thickness were sputter deposited onto single crystals of NiO. Continuous microscratch experiments were performed by driving a conical diamond indenter, with a nominal radius of 5 μm, simultaneously into and across the film until a load drop was observed indicating that the film had delaminated. The practical work of adhesion was calculated using a theoretical model developed for metal-ceramic systems. The practical work of adhesion increases from 0.03 to 4.7 J/m2 as the film thickness increases from 65 to 1080 nm. The practical work of adhesion includes the true work of adhesion — the energy to produce two new surfaces — and terms involving the plastic deformation of the film and substrate. Extrapolation of the practical work of adhesion versus film thickness data to zero thickness yields a first order estimate of the true work of adhesion. The true work of adhesion for the as-sputtered Pt/NiO system is determined to be 0.025 J/m2, a value of the same order as the Van der Waal’s energy.
Effect of Heat Treatment on Adhesion in the Cr/Al2O3 System
Authors: Viswanathan Sriram , Kohlstedt David L. 
Published: March 2011

ABSTRACTContinuous microscratch experiments have been carried out to investigate the effect of various heat treatments on adhesion in the Cr/Al2O3 system. After samples were prepared by vapor depositing 0.32 µm thick Cr films on (1102) surfaces of single crystal sapphire substrates, they were annealed at different temperatures at controlled oxygen partial pressures. In the subsequent continuous microscratch tests, a conical diamond indenter with a 1 µm tip radius was driven simultaneously into and across the sample until a load drop occurred. Optical and scanning electron microscopy observations demonstrate that a portion of the Cr film delaminated from the Al2O3 substrate at that point. The interfacial strain energy release rate was calculated from the load at failure combined with the size and geometry of the delaminated region. The work of adhesion was found to decrease dramatically on annealing in an H2-Ar mixture at 250°C.
Interface Structure and Adhesion of Sputtered Ti-Ni Layers on Silicon
Authors: Kondo Ichiharu , Yoneyama Takao , Kinbara Akira 
Published: March 2011

ABSTRACTInterface structure and adhesion between a Si substrate after an Ar ion bombardment pretreatment and Ni(100–1500 nm)/Ti(250 nm) double layers prepared in a dc magnetron sputtering apparatus have been investigated.Two extra layers were generated between the Ti layer and the Si substrate in as-deposited condition. One was an amorphous Si (a-Si) layer(∼ 2 nm) formed on the single crystal Si substrate surface which contains Ar atoms. Another is an amorphous Ti-Si (a-Ti · Si) mixed layer( ∼ 3 nm) on the a-Si layer. A peeling test with an adhesive tape showed that the peeling occurred at the interface between the a-Si and the a-Ti · Si. Ar atoms appeared to be distributed at the interface and the direct contact of the a-Ti · Si layer with the Si substrate seems to be prevented.After preparing the film and subjecting it to heat treatment at 623 K for 30 min, the adhesion decreased by the accumulation of Ar atoms at the interface. At 723 K for 30 min treatment, however, the adhesion increased probably because of Ar atoms diffusion. It is considered that the Ar atoms incorporated at the interface plays an important role on adhesion of the layer.
Phenomenological Explanation of Elastic Anomalies in Superlattices
Authors: Grimsditch M. , Fullerton Eric E. , Schuller Ivan K. 
Published: March 2011

ABSTRACTThe experimental fact that measured elastic and structural properties of superlattices are strongly correlated can be understood on the basis of a simple model based on the packing of hard spheres. The model is consistent with features of many models that have been proposed to explain the supermodulus effect, but contrary to previous explanations, it allows predictions for a given pair of constituents to be made. For an arbitrary pair of elements, it predicts the existence or non-existence of an elastic anomaly, and a rough estimate of its magnitude.
Residual Stress and Microstructure of CU/W Multilayers
Authors: Goudeau Ph. , Badawi K.F. , Naudon A. , Durand N. 
Published: March 2011

ABSTRACTWe have determined residual stresses and the layer microstructure in as-prepared Cu/W multilayers of different periods ranging from 5.2 to 20 nm by both X-ray diffraction and the curvature radius method. The magnitude of the principal in-plane stress is large in the W layers (around - 6 GPa) and small in the Cu layers (-0.5 - + 0.5 GPa). The stress state is independent of the multilayer period. Under the compressive stress, the W cubic unit cell becomes monoclinic-like. The stress-free lattice parameter is found higher than the bulk one.We also studied the stress relaxation and the layer microstructure modification in W layers induced by Kr ion irradiation., the relaxation is almost achieved after only low fluence irradiations and the decrease of the stress-free lattice parameter in W layers observed for higher fluences is attributed to the formation of a sursaturated solid solution W(Cu).
Thin Film Stress in Metal/Ceramic Microlaminates
Authors: Inturi R. B. , Barnard J. A. , Chinmulgund M. , Jarratt J. D. 
Published: March 2011

ABSTRACTAl/SiC multilayer microlaminates grown by sequential deposition of sputtered Al and SiC layers were used as a model system to study stress and mechanical properties of metal-matrix composites. The average stress in as-deposited and annealed microlaminates was determined as a function of laminate geometry. Film stress tends to approach constant values for increasing Al layer thickness, large numbers of bilayers, and high layer densities. Microlaminates with thin Al and SiC layers showed purely elastic deformation in σ -T tests to 400ºC. Even though the total measured film stress in a microlaminate geometry exhibited deviations from a simple rule of mixtures, the rate of change of stress with temperature in a microlaminate in the elastic region equals the sum of the slopes obtained separately from each of the individual layers.
Crack-Dislocation Modeling of Ductile-To-Brittle Transitions in Multilayered Materials
Authors: Anderson Peter M. , Li Canhao 
Published: March 2011

ABSTRACTUsing elastic fields of dislocations in a layered material, a simple form of a periodic potential is proposed to account for the fluctuation in dislocation line energy with position in a multilayer. This potential is incorporated into a fracture analysis which uses a Rice-Thomson criterion for dislocation emission [1] and a corresponding local stress intensity factor condition for cleavage extension. The analysis is rate-dependent, in that the velocity of a nucleated dislocation is proportional to the energetic force on that dislocation. Predictions of dislocation patterns in the vicinity of a crack parallel to the interface, as well as initial R-curve behavior, are discussed as a function of loading rate, layer thickness, and elastic properties of a two-component multilayer.
Studying Structure of Metallic Superlattices by "Symmetric" and "Asymmetric" X-rAY Diffraction
Authors: Gladyszewski G. , Goudeau Ph. , Badawi K.F. , Naudon A. 
Published: March 2011

ABSTRACT"Symmetric" and "asymmetric" x-ray diffraction measurements are proposed as a tool for quantitative and complete determination of the superlattice structure. A general procedure which takes into account the atomic structure of the sublayers as well as structural disorder are presented. The "asymmetric" geometry using the "sin2psi" method is particularly emphasized.
Molecular Dynamics Modeling of the Mechanical Behavior of Metallic Multilayers
Authors: Belak James , Boercker David B. 
Published: March 2011

ABSTRACTConstant-stress molecular dynamics simulations are used to study the mechanical properties of equal concentration Cu-Ni (111) metallic multilayers of repeat lengths 0.4–5.0 nm. Uniaxial stress is applied along the close-packed [110] and perpendicular to the close-packed [112] directions within the (111) plane. The observed elastic modulus does not display a super-modulus effect as observed in experimental bulge tests for the biaxial modulus. However, both the average interlayer spacing and the out-of-plane Poisson ratio display anomalous effects for multilayer repeat lengths below about two nanometers.
Using the Rule of Mixtures to Examine the Hardness of Cu/Cu-Zr Multilayers
Authors: Weihs T.P. , Barbee T.W. , Wall M.A. 
Published: March 2011

ABSTRACTCu/Cu-Zr multilayer foils were fabricated and indented to determine the degree to which multilayer hardness is enhanced by increasing the volume fraction of the harder phase. Using sputter deposition and thermal processing a series of foils was fabricated in which the thicknesses of the Cu layers remained fixed while the thicknesses of the alternate Cu-Zr layers varied. These samples were then indented both parallel and normal to their layering. In general, hardness increased as the volume fraction of the harder Cu-Zr phase rose. When the films were loaded parallel to their layering, the measured hardnesses were higher and the dependencies on volume fraction of the Cu-Zr phase were stronger than when the films were loaded normal to their layering. These results agree with predictions based on isostress and isostrain theories. The relationships between hardness and volume fraction are used to compare the hardnesses of the Cu-Zr phases: amorphous Cu-Zr, Cu51Zr14 and Cu9Zr2, and to show that the hardness of the textured, as-deposited Zr layers is highly anisotropic .