bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurement of Viscoelastic Stress Relief in Patterned Silicon-on-Insulator Composite Structures With Raman Spectroscopy
Authors: Létavic T. J. , Maby E. W. , Gutmann R. J. , Petruzzello J. 
Published: March 2011

ABSTRACTRaman spectroscopy has been utilized to measure room-temperature residual strain in the active device layer of laser-recrystallized silicon-on-insulator (SOI) composite structures. The SOI composite structures were fabricated on synthetic fused-silica substrates, and the composites contained a phosphosilicate glass (PSG) layer to provide high-temperature stress relief. Conventional masking and etching techniques were used to selectively pattern the polycrys-talline silicon layer into isolated square islands prior to recrystallization. The biaxial in-plane stress in recrystallized films was calculated from the measured strain-induced first-order Stokes Raman wavenumber shifts, and the results indicate that 200- μm-square recrystallized silicon islands have significantly lower in-plane stress values than continuous recrystallized silicon films. These measurements provide a preliminary confirmation of the dependence of the time constant for viscoelastic stress relief on the in-plane pattern dimension.
Eigenstresses in Anisotropic Films
Authors: Auricchio Ferdinando , Ferrari Mauro 
Published: March 2011

ABSTRACTA closed-form solution for a macroscopically homogeneous, fully anisotropie layer subject to non-uniform through-thickness eigenstrain is presented, and employed in determining the three-dimensional deformation and stress states of a thermally loaded ceramic film with microstructure-induced macroscopic anisotropy. The resultant stress field is compared with those that could be deduced by experimental determination of the curvature and the classical structural theories.
Tribological Properties of Superhard PVD Coatings
Authors: Knotek O. , Löffler F. 
Published: March 2011

AbstractIn order to advance the development of extremely hard coatings, new homogeneous and metastable films were prepared by magnetron sputter ion plating (MSIP) and arc ion plating (AIP) in the DC. or RF. mode.In the present study coatings in the systems Ti-B-C-N, Si-C-N and amorphous carbon coatings (ADLC) were investigated and compared with other hard coatings. Multicomponent layers of different compositions and structures were deposited by varying the reactive gases methane (CH4) and nitrogen (N2) and the dominant process parameters (e. g. C/V-characteristic of the cathode, substrate bias).X-ray diffraction studies of the Ti-B-C-N coatings revealed either an amorphous structure or crystallization in a hexagonal lattice. The ADLC and Si-C-N coatings were always amorphous. Electron microprobe analysis and auger electron spectroscopy were used to determine the coating compositions.The tribological properties were determined by a ball on disc tribometer (e.g. friction coefficent), a pin on disc tribometer and a special abrasive wear test.
Metal Reinforced Diamond Composite Films
Authors: Tsai C. , Nelson J. , Gerberich W. , Heberlein J. , Pfender E. 
Published: March 2011

ABSTRACTA three-step process for producing a composite diamond film is presented. Plasma deposited diamonds are reinforced by an electroplated metal binder and the diamonds regrown to produce a continuous, strongly adhered diamond film on molybdenum and tungsten substrates. Microscratching and pin-on-disk testing indicate that the composite films are more adherent than plasma deposited diamonds alone.
The Indentation Properties of Amorphous Boron Coatings Synthesized by Plasma-Enhanced CVD
Authors: Cooper C. V. , Shuskus A. J. 
Published: March 2011

ABSTRACTAmorphous boron coatings, ranging in thickness from 4 to 15 μm, have been synthesized via plasma-enhanced chemical vapor deposition using an rf plasma coil having serpentine rather than helical geometry for inductive coupling of the plasma. The power input to the rf coil has been established at five discrete levels ranging from 50 to 200 W during deposition from diborane onto Ti-6Al-4V substrates at 450°C. Deposition rates have been found to depend significantly on coil input power, reach in a saturation level of 15 μm/h at 100 W and higher but decreasing markedly with lower coil power levels. The amorphous nature of the coatings has been confirmed by selected area electron diffraction of extracted particles. Vickers and ultralow-load indentation experiments have been performed on boron coatings in cross-sectional and plan orientations, respectively. The ultralow-load hardnesses of the coatings deposited at all power levels exhibited relative independence from deposition power and ranged from 11.5 to 14.6 GPa. Vickers indentation in cross section produced hardnesses which were significantly greater than those using ultralow loading and an inconsistent dependence on deposition power.
Characterisation of Pointed Indentation Fracture of Thin Silica Films on a Ductile Substrate.
Authors: Samandi M. , Bell T. J. , Swain M. V. 
Published: March 2011

ABSTRACTObservations are presented of the indentation of amorphous silica films of different thickness on mild steel substrates. The films were prepared by sol—gel dip coating and sintering at 500° C. Indentation of the films with a Berkovich indenter using an ultra micro—indentation hardness system (UMIS) revealed a critical load for the fracture of the thin films. The variation of the fracture load was characterised by a Weibull analysis that gave a mean fracture load and a Weibull modulus. The latter was found to be nearly independent of film thickness whereas the former varied with the square of the thickness.
In Situ Study of Isothermal Strain Relaxation in Si-Ge Heteroepitaxial Films Using Substrate Curvature Measurements
Authors: Gillard Véronique T. , Noble David B. , Nix William D. 
Published: March 2011

ABSTRACTUnderstanding die kinetics and mechanisms of strain relaxation in Si-Ge heteroepitaxial films is pertinent to several device applications. In this paper we present a method for determining the evolution of the mobile dislocation density with time during the course of strain relaxation taking place in an isothermal annealing experiment.Wafer curvature measurements using a laser scanning technique are used to determine the elastic strain after growth in films of variable thickness and to follow the strain relaxation during isothermal annealing experiments. By coupling the strain relaxation measurements with previous TEM measurements of dislocation velocities in this system, the mobile threading dislocation density and its evolution with time are determined.
The Critical Thickness of Layers Subject to Anisotropic Misfit.
Authors: Beanland Richard 
Published: March 2011

ABSTRACTIt is well known that it becomes energetically favourable for misfit dislocations to be introduced into strained epitaxial layers above a certain ‘critical’ layer thickness, hc. To date, theoretical calculations of hc have only been made for cases of isotropie misfit - i.e. cases where the misfit is the same for every direction in the interface. Using a new formulation of the Frank-Bilby equation and the concept of coherency dislocations, it is now possible to treat cases of anisotropie misfit, such as silicon on sapphire (SOS). The method used to obtain the critical thickness is described, and values of hc and equilibrium dislocation density are given for various materials systems.
Strain Shift Coefficients for Phonons in Si-Ge Heterostructures
Authors: Baribeau J.-M. , Lockwood D. J. 
Published: March 2011

ABSTRACTStrain shift coefficient measurements for longitudinal optical phonons in molecular beam epitaxy grown metastable pseudomorphic Si1−xGex layers on (100) Si (0 < x < 0.35) and Ge (0.80 < x < 1) are reported. Strain in partially relaxed annealed specimens was obtained by double-crystal x-ray diffractometry and the corresponding strain phonon shift was measured by Raman scattering spectroscopy. For epilayers grown on Si it was found that the epilayer Si-Si phonon frequency varies linearly with strain. The magnitude of the strain shift coefficient b however showed a small composition dependence varying from b ≈ -700 cm-1 at x = 0 to b ≈ -950 cm-1 at x = 0.35, corresponding to a stress factor τ = 0.40 + 0.57x: + 0.13x2 cm-1/kbar. For the Ge-Ge vibration mode in epilayers grown on Ge, b decreased from ∼-425 cm-1 at x = 1 to ∼-500 cm-1 at x = 0.8, corresponding to a stress factor τ ≈ 0.52 – 0.14x - 0.08x2 cm-1/kbar.
Structure and Mechanical Properties of Fe/Zr Multilayers.
Authors: Vlassak Joost J. , Nakayama Takenori , Konno Toyohiko J. , Nix William D. 
Published: March 2011

ABSTRACTIron zirconium multilayer films have been prepared by sputter deposition and studied using x-ray diffraction, high-resolution transmission electron microscopy and Nanoindenter techniques. The composition-modulation wavelength was varied between 0.8 and 92 nm. For modulation wavelengths greater than 4 nm the multilayers are crystalline with amorphous interfaces; for smaller wavelengths the samples are entirely amorphous. It was not possible to obtain layered structures with wavelengths smaller than 0.8 nm.Both the hardness and the elastic modulus were measured as a function of composition-modulation wavelength by means of continuous indentation testing. The elastic modulus shows some variation with wavelength; the average value being 131 GPa. The hardness increases sharply when the modulation wavelength decreases below 4 nm. We attribute this increase to die crystalline to amorphous transition that occurs in these films at this wavelength.
Zero Creep Measurements of the Interfacial Free Energy of Ag/Ni Multilayers
Authors: Josell D. , Spaepen F. 
Published: March 2011

ABSTRACTThe free energy γAgNi associated with an interface between layers of silver and nickel has been experimentally determined. Creep tests were conducted on multilayer thin films to determine the load at which the length of the film neither shrank nor stretched. The interfacial free energy was obtained from this zero creep load and microstructural data using a specific model for the grain boundary diffusional creep in multilayers.
Strain Analysis in PbTe/PbMnTe Superlattices by X-Ray Diffraction
Authors: Koppensteiner E. P. , Krenn H. , Frank N. , Bauer G. 
Published: March 2011

ABSTRACTThe strain tensor components of the PbTe and PbMnTe constituent layers of three superlattices grown on (111) oriented BaF2 substrates are determined from an X-ray analysis. Symmetric (222) and asymmetric (426), (224), (244) Bragg reflections were analysed and a generalization of the Hornstra-Bartels model is used, assuming that the SL (superlattice) can be simulated accordingly. Since in the multilayers also the satellites of the symmetric and asymmetric reflections have been considered the strain tensor components were determined with an accuracy of 1.5×10-4. Consequently the Mn-content of the PbMnTe layers could be determined with an accuracy of ± 0.03%.
Tensile Stress-Strain Properties of a-C:H (Diamond-Like Carbon) thin Films
Authors: Garrett Paul D. , Daniels Brian K. 
Published: March 2011

ABSTRACTFundamental mechanical properties of a-C:H (amorphous or “diamond-like” carbon, DLC) thin film coatings have been investigated. Coatings were deposited by a methane-argon RF plasma on polycarbonate films. Tensile stress-strain behavior of the coated polymer was studied using an extensometer to monitor strain. The differences in moduli between uncoated and coated samples were used to calculate apparent coating moduli, which varied from 1 GPA to 82 GPa. The mode of failure was observed via in-situ optical microscopy during deformation. Intrinsic bond strength of the coating/substrate interface was estimated from crack spacings in the deformed coating.
Electromigration in Aluminum Based Interconnects of VLSI-Microcircuits, with and without Preceding Stress-Migration Damage
Authors: Korhonen M. A. , Børgesen P. , Li Che-Yu 
Published: March 2011

ABSTRACTIn the narrow, confined metal interconnects used in the chip level, electromigration flux is resisted by the evolution of mechanical stresses in the interconnects. Recently there has been a growing concern on the effects of preceding stress-migration on the subsequent electromigration damage. We present here an electromigration model, which is able to address the effects of stress-migration and mechanical stresses on electromigration lifetime.
Effect of Hydrogen on Thin Cu/Ti and Cu Films
Authors: Apblett Christopher A. , Ficalora Peter J. 
Published: March 2011

ABSTRACTThin films of Cu and Cu on Ti were prepared by sputtering films onto SiO2 substrates. The films were annealed at temperatures between 350 and 400°C in vacuum and hydrogen ambiente. The stress was measured in-situ during the anneals. The stress in vacuum initially was compressive, then became tensile and remained so. The stress in hydrogen started in compression and remained so throughout the anneal. The origin of these stresses is explained as a result of compound formation. In vacuum anneals, TiCu forms during the compressive stage with an activation energy of 1.7 eV, then TiCu3 forms during the tensile stage with an activation energy of 2.5 eV. In hydrogen, a single compound, TiH2, forms under the Cu with an activation energy of 0.93 eV.Studies on the Cu films indicate that hydrogen reduces the incremental stress formed in the films during annealing. A possible explanation is presented for the stress change in that hydrogen has been shown to assist in annealing dislocations. Experimental evidence of an instantaneous change in the stress state upon the introduction of a new ambient is also presented.
Ceramics as Engineering Materials: Structure-Property-Processing
Authors: Kent Bowen H. 
Published: March 2011

ABSTRACTCeramic materials are currently being used in many applications and account for about $26 B of the U.S. economy in low value-added products (glass, refactories, cement, whitewares, etc.) and nearly $4 B of high value-added components (chip carriers, waveguides, capacitors, cutting tools, etc.). There are many new applications of ceramics in high technology engineering systems which will result in significant growth of the ceramics business if the materials research triad Structure-Property-PROCESSING moves from the laboratory to the manufacturing plant. Each component can be classified by function (e.g., thermal, mechanical, electromagnetic, optical, biological, and nuclear); configuration (e.g., film, monolith, composite, porous, and single crystal); or processing route (e.g., powder processing, glass forming, and crystal growth). The opportunities are greatest for those components which have a well established processing science base or an unique fabrication method.Thirty years of research have shown that the critical physical/chemical properties are strongly related to the structure on one or more levels: few angstroms - crystal structure and phases; 10–100 Å - boundary or grain boundary layers or phases; 1 μm - microstructure (grain size, porosity, interpenetrating phases, etc.); and macro-structure including joining, shape and dimensional tolerances. The major focus of this overview relates to issues of reliability and reproducibility in processing polycrystalline ceramics and the relationship between processing and the control of the structure and properties. Examples considered are those of high value-added components where design and functionality justify improved material characteristics.
UV Photoemission Study of Defect States in Polyethylene Films
Authors: Pong W. , Brandt D. , Sato A. , Imaino W. , Farrow M. 
Published: March 2011

ABSTRACTPhotoemission from evaporated Polyethylene films was measured in the spectral region between 6 and 11 eV. A significant increase in photoemission yield was observed after the films were exposed to O2 and to air containing ozone and ions from a diffuse glow discharge at reduced pressures. The enhancement can be attributed to oxygen and ozone reacting with the defects in the evaporated polyethylene films, which are unsaturated carbon double bonds in the polyethylene chain. For the ozonized polymer films deposited on gold substrates, the photoelectron spectra show a relatively high density of occupied states at 6.8 ± 0.3 eV below the vacuum level of the polymer and a photoemission threshold of 3.8 ± 0.3 eV. The implication of the results to contact charging of polyethylene is discussed.
The Effect of Ionizing Radiation on Nickel-Doped MgO.
Authors: Boldú J. L. , Muñoz P. E. , Tsang K. L. , Abraham M. M. , Chen Y. 
Published: March 2011

ABSTRACTDefect and impurity valence changes induced by γ irradiation of nickel- doped MgO crystals are studied using magnetic resonance and optical techniques.
Photoplasticity in HgCdte
Authors: Galligan J. M. , Pellegrino J. , Manzur T. 
Published: March 2011

ABSTRACTA time delay has been observed in HgCdTe in the photoplastic response of these crystals. Both the magnitude of the time delay and the total change in stress, Δσ, are dependent on the wavelength of the light. These observations provide a basis for establishing that the photoplastic process is a dynamic one, in contrast to prior treatments of the problem as a static process. Solution of the kinetics associated with this time delay allow us to show the dynamical character of photoplasticity.
Dynamic Consolidation of Ceramic Powders: Practicalities, Problems, and Prospects
Authors: Gourdin William H. 
Published: March 2011

ABSTRACTI present an assessment of the technological potential ofshock wave consolidationof ceramic powders as a technique for producing well-bonded, uniform, crack-free monoliths. Current compaction methods are briefly reviewed and the characteristics of the consolidated material are presented. The shock and release histories experienced by powder compacts in simple compaction assemblies are complex and I conclude that such simple assemblies are unlikely to yield structurally sound bodies. Control of the stress history over the entire loading cycle is necessary if the tensile stresses which develop during release are to be reduced to acceptable levels. Such exacting control is difficult to achieve, and becomes increasingly difficult as the peak stresses are increased. The powder must therefore be sufficiently plastic at moderate stresses to permit densification and bonding of the compact without destruction of the compact during release. Not all ceramic powders will satisfy this criterion. Local microstructural modification, including interfacial melting, is limited by the fine particle sizes and large surface areas of many ceramic powders. Production of cohesive, crack-free bodies thus depends upon a complex interplay between shock history, material properties, and powder characteristics which is poorly understood. I conclude that the technology of dynamic consolidation of ceramic powders will be difficult to develop and will have limited applications.
Fast Diffusion of Iron in Single Crystal Rutile and Iron Doped Rutile
Authors: Sasaki J. , Peterson N. L. , De Jonghe L. C. 
Published: March 2011

ABSTRACTTracerdiffusioncoefficients of Fe, DFe*in single crystals of rutile and of 0 –2.0% Fe doped rutile were measured. The oxygen pressure dependence of DFe* in pure rutile showed complicated behavior. The values of DFe* may consist of contributions from Fe2+ions diffusing by an interstitial mechanism and from Fe3+ions diffusing by an interstitialcy mechanism in cooperation with tetravalent titanium interstitial ions, Tii. The value of DFe* in Fe doped rutile attains a saturation value when the Fe content reaches about 0.1%, D*Fedecreases drastically when the Fe content exceeds about 0.35%. Complex impedance measurements ofelectrical conductivityindicate the existence of ionic conduction for Fe doped rutile containing less than 0.35% of Fe. The small ionic conductivity relative to the values of D*Fesuggests that only a small fraction of the iron ions are highly mobile. Above 0.35% Fe, the observed drastic decrease in D*Femay result from the formation of a shear structure In highly doped rutile.
Recent Advances in Solid-State Laser Materials
Authors: Moulton Peter F. 
Published: March 2011

ABSTRACTAfter some years of relatively little activity, the field of solid-state lasers has again become an important research area. Laser operation has been demonstrated in new combinations of laser-active ions and host crystals to provide wavelength-tunable output and the promise of greatly improved efficiency. This paper will discuss several currently interesting classes of laser materials: divalent-transition-metal-doped, rutile- and perovskite-structured fluoride crystals such as Co:MgF2 and V:KMgF3 , Ti3+-doped materials including Ti:A12O3 and a variety of large-lattice-size garnet crystals doped with Cr3+ and/or Nd3+.
On the Role of Schottky Disorder on the Stability and Structure of (100) Twist Grain Boundaries in Nio
Authors: Wolf D. 
Published: March 2011

ABSTRACTRecent calculations on (100) coincidence-site lattice (CSL) twist boundaries in the NaCl structure have shown that without point defects these boundaries are only marginally stable. Following an earlier suggestion that point defects are the likely source for the considerable stability of these boundaries observed experimentally for Mgo and NiO, Tasker and Duffy have shown recently that the creation of a Schottky pair can, indeed, stabilize a (100) twist boundary in NiO. In this article a variety of configurations in which one or more Schottky pairs have been created in the perfect CSL or anti-CSL unit cell are investigated. It is concluded that many metastable structures may exist which differ mainly with respect to their different interfacial mass densities and the relative translation of the two halves of the bicrystal.
Characterisation of Thin Lattice Mismatched Heteroepitaxial Layers by XRD
Authors: Halliwell Mary A. G. 
Published: March 2011

ABSTRACTMany advanced III - V devices require highly strained heteroepitaxial layers less than 25 nm in thickness, with tight specifications on both the layer thickness and composition. In many cases the layers required are close to the critical thickness.The growth conditions for these thin layers are often extrapolated from established conditions for thicker layers. This method can result in layers which have the incorrect thickness and composition because of the transients which occur as growth commences. To minimise this problem it is desirable to establish growth conditions for layers which are as close to device requirements as possible. X-ray diffraction is capable of measuring layer thicknesses and compositions non-destructively. The minimum measurable layer thickness is usually within a small factor (typically 0.5 to 5 times) of device requirements.A single x-ray rocking curve is required to determine the thickness and composition of an unrelaxed (strained) layer. At least two rocking curves are required when relaxation is present. This paper discusses the appropriate choice of measurement conditions for a given sample.
Dynamical X-Ray Diffraction Studies of Interfacial Strain in Superlattices Grown by Molecular Beam Epitaxy
Authors: Vandenberg J. M. , Chu S. N. G. , Hamm R. A. , Panish M. B. , Ritter D. , Mancrander A. T. 
Published: March 2011

ABSTRACTDynamical X-ray diffraction studies have been carried out for lattice-matched InGaAs/InP superlattices grown by modified molecular beam epitaxy (MBE) techniques. The (400) X-ray satellite pattern, which is predominantly affected by the strain modulation, was analyzed. The strain and thickness of the actual layers including the presence of strained interfacial regions were determined.