bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of Ion-Implanted SiO2 Properties Applicable to Laser Processing
Authors: Teng T. C. , Shiau Y. , Chen Y. S. , Skinner C. , Peng J. D. , Palkuti L. J. 
Published: March 2011

ABSTRACTThe use of an antireflection oxide film applicable to laser annealing process has been investigated. The optical properties of the antireflection oxide film are changed by ion implantation although the antireflection characteristics are similar to calculations based on nominal optical constants. Implantation annealing can be achieved at powers lower than predicted by calculations. Using the antireflection(AR) technique, n+-p junction diodes were fabricated. Reverse bias junction leakage is around 10-9 A/cm2 , comparable to those annealed thermally. Short channel MOS devices were also fabricated and indicated much better resistance to the short channel effect than those thermally annealed.
Laser Epitaxy Over Buried Layers
Authors: Weeks S. P. , Celler G. K. , Leamy H. J. 
Published: March 2011

ABSTRACTThe redistribution of antimony impurity atoms implanted in (111) and (100) substrates was studied as a function of the power density of Q-switched YAG laser radiation (λ = 0.53μm) used to recrystallize 4700Å films of amorphous silicon vapor deposited over blanket and patterned Sb buried layer structures. Results for fully crystallized layers show impurity profiles ranging from a sharp interface displaced outward slightly relative to the as-grown interface, to complete redistribution of antimony into the deposited layer. Studies of patterned buried layer structures indicate that epitaxial crystallization can be achieved on (111) and (100) substrates without serious damage to the surface topography necessary for subsequent mask alignment.
Pulsed Laser Recrystallization of Polysilicon: Analysis Via A Novel Sem Technique
Authors: Shah Rajiv R. , Crosthwait D. Lloyd 
Published: March 2011

ABSTRACTLarge crystals of silicon were obtained via pulsed laser annealing of thinfilms of fine grain CVD polycrystalline silicon. These films were analyzed using a novel technique that provides rapid feedback of crystallographic and defect information. The technique uses very shallow angle metallurgical sections in conjunction with chemical decoration and scanning electron microscopy and results in excellent depth resolution (<10 nm) across large spatial distances (>100 μm). The technique was used to reveal conversion of very large areas (≈ 1 mm 2) of polysilicon films deposited on silicon into single crystal film, albeit with point defects, without requiring the melt depth to reach the polysilicon/silicon interface. A gradual transition from single crystal to increasingly polycrystalline material was observed going from top to bottom of the initially uniform polycrystalline film depending on the pulse energy used. Polysilicon on top of an oxide layer, on the other hand, transforms into large (≈ 10 μm) single crystals with grain boundaries penetrating the entire polysilicon film thickness. These experimental results shed new light on two very important questions: (1) Is laser annealing entirely an epitaxial process or is it strongly influenced by the thermal properties of the underlying substrate, and (2) Whether substantial regrowth of polysilicon requires equilibrium thermodynamics.
Silicide Formation using Laser and Electron Beams
Authors: Sigmon T. W. 
Published: March 2011

ABSTRACTThe reaction of thin metal films with single crystal or amorphous silicon to form silicide compounds has been successfully undertaken using both scanned-cw and pulsed beam processing. Similar to the case for beam annealing of ion-implanted semiconductors, both the basic mechanisms and the experimental results are found to depend on whether pulsed or scanned beams are used to promote the reactions. For both cases the experimental results are often found to differ sharply from those obtained with standard furnace processing. For the pulsed beam reaction, melting and rapid resolidification occurs in the metal silicon films. The principal result is that the reacted film is frozen in a mixed phase compound which can consist of several silicide compounds including silicon and metal precipitation. Compositions inaccessible by conventional furnace annealing can also be formed by this process. In contrast to the pulsed beam results, scanned-cw beam processing of metal silicon films is found to result in the formation of large area uniform silicide phases with essentially no silicon or metal precipitation. These films are generally found to be homogeneous with well defined silicon/silicide interfaces.
Metastable Alloy Formation in Electron Beam Pulsed Al and Si
Authors: Picraux S. T. , Follstaedt D. M. , Knapp J. A. , Wampler W. R. , Rimini E. 
Published: March 2011

ABSTRACTThe formation of metastable alloys by pulsed electron beam annealing of Al implanted with Sn or Ni and of Si implanted with Sn has been studied by TEM, ion backscattering and channeling. Surface segregation after pulsed melting is observed in Si but not in Al, even though all impurities have similar equilibrium distribution coefficients of∼10-2. This difference is attributed to the higher liquid-solid interface velocity and lower diffusivities in Al. Metastable substitutional solutions more than an order of magnitude above equilibrium solubilities are obtained for Ni and Sn in Al. At Ni concentrations ∼ 5 at.% a highly disordered transformation zone is formed in Al and a new phenomenon in which a polycrystalline layer forms on epitaxially regrown Al is observed.
Oxide Superconductors: A Chemist's View
Authors: Sleight A. W. 
Published: March 2011

ABSTRACTThe brief history of oxide superconductors is presented and discussed in terms of structure, bonding and property interrelationships. The perovskite structure has been very prominent in the history of oxide superconductors, including the recently discovered copper oxide based superconductors. However, an alternate description of the high Tc superconductors in terms of sheets, chains and sticks may be more useful. Although chains and orthorhombic symmetry in RBa2Cu3O7 phases favor high Tc superconductivity, orthorhombic symmetry is not required to have well developed chains and reasonably high Tc (e.g ∼60 K). Furthermore, highly disordered LaBa2Cu3O7 and YBa2Cu3O6.7 phases are not superconducting even though they are weakly orthorhombic. Superconducting RBa2CueO6+x phases are prepared by oxygen intercalation of a semiconducting phase with a low x value; intercalation phases are not normally expected to be thermodynamically stable. A mechanism for superconductivity in oxides is presented based on disproportionation reactions such as 2CuII → CuI + CuIII and 2BiIV → BiIII + Biv.
Effect of GaAs Surface Stoichiometry on The Interface of As-Grown Epitaxial ZnSe/Epitaxial GaAs Heterostructures
Authors: Qiu J. , Gunshor R.L. , Kobayashi M. , Menke D.R. , Qian Q.-D. , Li D. , Otsuka N. 
Published: March 2011

ABSTRACTIn the study reported here, the GaAs surface stoichiometry was systematically varied prior to the nucleation of ZnSe to form epitaxial ZnSe/epitaxial GaAs interfaces. The structures were grown by molecular beam epitaxy and evaluated by several techniques including capacitance-voltage (C-V) measurements. A dramatic reduction of interface state density occurred when the GaAs epilayer was made As deficient. The resulting interface state densities of as-grown structures are comparable to values obtained with (Al,Ga)As/GaAs interfaces.
The Effect of Surface Layers in Epitaxial N-Type Hg1−xCdxTe
Authors: Parat K.K. , Taskar N.R. , Bhat I.B. , Ghandhi S.K. 
Published: March 2011

ABSTRACTThe presence of low mobility surface electrons on n-Hg1−1CdxTe is generally not apparent in the temperature dependence of the Hall Coefficient (RH) or the Hall mobility (µH) of the layer. However, its influence is clearly seen in the magnetic field (B-field) dependence of RH. The B-field dependence of RH can be analyzed to extract the bulk and surface carrier concentrations and their respective mobilities.This diagnostic technique has been used for evaluating epitaxial Hg1−xCdxTe layers grown by organometallic vapor phase epitaxy (OMVPE), which have been converted to n-type by annealing in Hg overpressure. In addition, the effect of anodic sulfide passivation on the B-field dependence of Hall coefficient is also outlined.
Vapour Pressure Measurements on Organotellurium Precursors for Movpe
Authors: Hails J.E. , Irvine S.J.C. , Mullin J.B. 
Published: March 2011

ABSTRACTBefore an organometallic compound can be used as an MOVPE precursor, certain basic properties need to be known and one of the most important of these is vapour pressure. A technique for the measurement of vapour pressures using an MOVPE system designed for precursor assessment is described. Results on the assessment of di-is-propyl-telluride, di-n-propyl-telluride, di-allyl-telluride, methyl-allyl-telluride and di-t-butyl-telluride are presented.
MBE Growth and Characterization of Small Band Gap HgTe-HgCdTe Superlattices.
Authors: Lansari Y. , Yang Z. , Hwang S. , Cook J.W. , Schetzina J.F. 
Published: March 2011

ABSTRACTA series of modulation-doped small-band-gap HgTe-Hg1−xCdxTe superlattices (SLs) have been grown by photoassisted MBE. N-type or p-type conductivity was obtained in the modulation-doped samples by incorporating either In or As dopant atoms in the barrier layers, respectively. The electrical and optical properties that these new multilayered quantum well structures display will be discussed.
On The Field Fmisiicn Fwom HgTe-CdTe Superlarrices with Graded Struijctures Under Magnetic Quantization
Authors: Ghatak Kamakhya P. , Biswas Sambjij N 
Published: March 2011

ABSTRACTIn this paper, we studied the magneto-field emission from HgTe/Cdre superlattices with graded structure and compared the same with the bulk specimens of the constituent materials. It is found that the field emitted current density increases both with electron concentration and magnetic field in an oscillatory manner. The field emission in HgTe/CdTe SLi is greater than that of the same from constituent materials the theoretical results are in agreement with the experimental observation as reported elsewhere.
Tem Study of Defects In CdTe/CdMnTe Superlattices on (100) InSb
Authors: Diamond S.J. , Steeds J.W. , Ashenford D. , Lunn B. 
Published: March 2011

ABSTRACTCdTe/Cd1−xMnx Te superlattices with well/barrier thicknesses ranging from 20Å to 300Å were examined via plan and cross section TEM in analytical instruments capable of EDX and CL. Misfit dislocations, inclined dislocations and stacking faults were observed with a net density of around 109cm−2.It was observed that the dislocations originated near the substrate/epilayer interface and that stacking faults appeared preferrentially on the pair of {111}B (tellurium terminated) planes in the growth direction rather than on the {111}A planes.It is suggested that this is due to a difference in mobility between a and P dislocations originating at or near the substrate.
Ga and In Autodoping of Cdt, MnxTe Epitaxial Layers Grown on GaAs and InSb Substrates
Authors: Dubowski J.J. , Wrobel J.M. , Rolfe S. , Jackman J.A. , Mazur J.H. , Noadw J. 
Published: March 2011

ABSTRACTA study of Ga and In outdiffusion into Cd1−xMnxTe (0≥ x ≥ .70) epitaxial layers grown on (111)GaAs and (001)lnSb was carried out. The layers were grown by pulsed laser evaporation and epitaxy on substrates held at temperatures below 310 °C. The structural quality of the layers was examined using x-ray diffraction and transmission electron microscopy. A tendency toward precipitation of Ga at the near surface region of (11 1)CdMnTe grown on (11 1)GaAs, usually less than 300 nm wide, has been observed with secondary ion mass spectroscopy. Similar results were observed for the migration behaviour of In in (001)CdTe grown on (001)InSb. The ion imaging revealed that both In and Ga accumulate near the surface at localized spots, up to about 10 pm in diameter. The concentration of the spots is in the range of 104 - 106 cm−2. The Ga- and In-rich channels sometimes extend over the whole sample. Annealing at temperatures as low as 400 °C for 2 h significantly increases the concentration of the Ga spots and the average concentration of Ga in the films to above 1016 cm−3. Low-temperature photoluminescence data obtained for annealed samples do not indicate any structural deterioration typical for heavily doped Bridgman grown samples. A sharp neutral-donor bound-exciton transition (D°,X) is observed for samples with 0 < x < .10.
Ion-Implantation Getiering of Impurities in CdTe
Authors: Jin M. H. , James K. M. , Jones C. E. , Merz J. L. 
Published: March 2011

ABSTRACTThis is the first reported use of ion-implantation damage gettering of impurities in CdTe to provide high-quality substrates for the epitaxial growth of appropriate binary or ternary compounds, or for related applications. We describe the results of photoluminescence (PL) measurements performed on samples of Bridgeman-grown CdTe to study both the annealing behavior and gettering effects in this material. From the PL results, it was found that impurity gettering occurs at temperatures at which liquid phase epitaxy take place (∼500°C) so that these two fabrication procedures are compatible. It was also found that the optimum anneal time at this temperature is four hours.
3d Transition Metals in II-VI Semiconductors
Authors: Heiman D. , Dahl M. , Wang X. , Wolff P.A. , Becla P. , Petrou A. , Mycielski A. 
Published: March 2011

ABSTRACTThe magnetic and electronic properties of some I-VI semiconductors with 3d transition metals other than Mn are presented. For example, the nonzero orbital moment in Fe2+ leads to more complex electronic energy levels than for Mnt ions. In (CdFe)Se, inelastic light scattering experiments demonstrate that the ground state is nonmagnetic (Van Vleck ion), and directly measures the energy spacing between the three lowest levels. For Sc2+ ions the donor level lies above the bottom of the conduction band in the Cd-based materials.
Magnetization Study of Fe-Based II-VI Diluted Magnetic Semiconductors
Authors: De Jonge W.J.M. , Swagten H.J.M. , Twardowski A. 
Published: March 2011

ABSTRACTThe high field magnetization for Fe based Diluted Magnetic Semiconductors has been calculated. It is shown that the low temperature magnetization displays characteristic steps, related to the nearest neighbour exchange interaction JNN, provided that JNN exceeds a critical value.
Characterization of Interfaces in SiC Particulate-Reinforced Al Alloys by AEM
Authors: Robertson Brian W. , Holm Chandra , Lin Yang-Pi , Corbin Stephen F. J. , Wilkinson David S. 
Published: March 2011

AbstractAs a preliminary step to detailed study of the interfaces in SiC particulatereinforced Al alloys, a number of methods of sample preparation have been explored; the resultant artefacts on the thinned foils observed in transmission electron microscopes are discussed and improvements to the preparation procedures are suggested. Initial observations of the microstructure of two alloys differing significantly in their matrix silicon content are presented.
The Influence of Annealing on the Behaviour of Epoxy-Glass Interphases
Authors: Schröder U. , Marzi T. , Heß M. , Kosfeld R. 
Published: March 2011

AbstractDynamic-mechanical measurements were used to study the properties of the interphase in glass fibre reinforced epoxy resins. The immobilisation of the polymer chains in the interphase is determined by the curing system, the annealing process, and the surface treatment of the glass fibres.
Interface Properties for Ceramic Composites from a Single-Fiber Pull-Out Test
Authors: Butler Elizabeth P. , Fuller Edwin R. , Chan Helen M. 
Published: March 2011

AbstractAn experimental approach has been developed using a single-fiber pullout test to measure intrinsic interface properties for ceramic composites. The properties are determined from a pull-out, force-displacement curve, which is directly related to reinforcement toughening via fiber/matrix debonding and frictional pull-out. They were evaluated for a model composite system of continuous SiC fibers with various surface treatments in a borosilicate glass matrix. For the processing conditions used, the interface fracture toughness and the interface frictional shear resistance were found to be 1.0 ± 0.5 J/m2 and 3.3 ± 0.6 MPa, respectively, for as-received fibers. Experiments conducted with long embedded fiber lengths allowed the shear resistance to be deconvolved into an interface friction coefficient of 0.05 ± 0.01 and an initial fiber-clamping pressure of 65 ± 6 MPa. Nitric acidwashed fibers gave an increased interface toughness of 3.6 ± 0.1 J/m2 and friction coefficient of 0.08 ± 0.02, but nearly the same initial clamping pressure, 72 ± 12 MPa. Calculations of the clamping pressure from the fiber/matrix thermal expansion mismatch and from stress birefringence measurements in the glass were in general agreement with this value.
The Role of Crystallization of an Intergranular Glassy Phase in Determining Grain Boundary Residual Stresses in Debased Aluminas
Authors: Padture Nitin P. , Chan Helen M. , Lawn Brian R. , Readey Michael J. 
Published: March 2011

AbstractThe influence of microstructure on the crack resistance (R-curve) behavior of a commercial debased alumina containing large amounts of glassy phase (28 vol %) has been studied using the Indentation-Strength test. The effect of two microstructural variables, viz. grain size and the nature of the intergranular second phase (glassy or crystalline) has been evaluated. Crystallization of the intergranular glass was carried out in order to generate residual stresses at the grain boundaries, which have been shown to enhance R-curve behavior in ceramic materials. Enhancement of the R-curve behavior was observed with the increase in grain size. However, no effect of the nature of the intergranular second phase on the R-curve behavior, in small and large grain materials, was observed. The results from characterization of these materials using various analytical techniques is presented, together with possible explanations for the observed effects.
The Production of Modulus Gradients at Interfaces
Authors: Garton Andrew , Haldankar Gautam , Shockey Edward 
Published: March 2011

AbstractWe have developed a range of “antiplasticizing” additives for epoxy and polyimide resins which can increase the modulus of the cured polymers by > 40%, increase their tensile and shear strengths, modify their fracture behavior, and decrease their water uptake. These additives may be used alone or in conjunction with rubber modifiers. The optimum additive formulations are complex mixtures, but we describe here two relatively pure model systems. The epoxy additive is the reaction product of 4-hydroxyacetanilide (HAA) and vinylcyclohexene dioxide (VCD), while the polyimide additive is the reaction product of epoxyphenoxypropane (EPP) and HAA. These additives are mixed with the epoxy resin and curing agent (or polyamic acid solution in the case of polyimides), before curing, and the mixture is then cured in the conventional fashion. We describe here some physical properties of the modified epoxies and polyimides and their use in adhesive formulations. These materials offer the potential for constructing modulus gradients at interfaces through their use as primers, so as to allow testing of the many hypotheses concerning desirable interphase properties. Some initial experiments in this area are described.
Correlation Between Fibre Surface Energetics and Fibre-Matrix Adhesion in Carbon Fibre Reinforced Peek Composite
Authors: Hodge D J , Middlemiss B A , Peacock J A 
Published: March 2011

AbstractSurface energies of carbon fibres at different levels at surface treatment have been determined by a wetting force technique and related to fibre-matrix adhesion in carbon fibre reinforced PEEK composite. The effect of oxidative surface treatment on the surface free energy is detailed, along with the changes in surface oxygen and nitrogen content, as determined by X-ray photoelectron spectroscopy (XPS). The work of adhesion has been calculated for the carbon fibres and thermoplastic, which correlate well with experimental determination of interfacial strength. The technique can therefore be used to predict adhesion levels in fibre reinforced composites.
Effect of Surface Oxygen on Adhesion of Carbon Fiber Reinforced Composites
Authors: Yip P. W. , Lin S. S. 
Published: March 2011

AbstractFive carbon fibers from different precursors were surface treated by various chemical reagents for the elucidation of the mechanism involved in interfacial adhesion. SEM, ESCA and SAM techniques were used to characterize morphology as well as surface constituents of the treated fibers. The transverse tensile strengths of the composites made from the treated fibers and epoxy resin were also obtained. The result indicated that the interlocking mechanism by surface roughness seemed to play a major role in the fiber-epoxy adhesion.
Interlaminar Fracture in Carbon Fiber/Thermoplastic Composites
Authors: Hinkley J. A. , Bascom W. D. , Allred R. E. 
Published: March 2011

AbstractThe surfaces of commercial carbon fibers are generally chemically cleaned or oxidized and then coated with an oligomeric sizing to optimize their adhesion to epoxy matrix resins. Evidence from fractography, from embedded fiber testing and from fracture energies suggests that these standard treatments are relatively ineffective for thermoplastic matrices. This evidence is reviewed and model thermoplastic composites (polyphenylene oxide/high strain carbon fibers) are used to demonstrate how differences in adhesion can lead to a two-fold change in interlaminar fracture toughness.The potential for improved adhesion via plasma modification of fiber surfaces is discussed. Finally, a surprising case of fiber-catalyzed resin degradation is described.
A New Theory for the Debonding of Discontinuous Fibers in an Elastic Matrix
Authors: Leung Christopher K. Y. , Li Victor C. 
Published: March 2011

AbstractThe mechanical properties of fiber composites are strongly influenced by the debonding of fibers. When an embedded fiber is loaded from one end, debonding can occur at both the loaded end and the embedded end. Existing theories neglect the possibility of debonding from the embedded end and are thus limited in applications to cases with low fiber volume fraction, low fiber modulus, high interfacial strength/interfacial friction ratio or short fiber length. A new twoway fiber debonding theory, which can extend the validity of one-way debonding theories to all general cases, has recently been developed. In this paper, the physical reason for the occurrence of two-way debonding is discussed. The limit of validity for one-way debonding theories is considered. One-way and two-way debonding theories are then compared with respect to the prediction of composite behaviour. The determination of interfacial parameters from the fiber pull-out test will also be described.
Solid State Bonding of Si3N4 and Ni
Authors: Wang Jian-Yih , Hsu Shu-En , Suga Tadatomo , Ishida Yoichi 
Published: March 2011

AbstractSolid state bonding of Si3N4 and Ni is considered to be a simple ceramic/metal diffusion bonding as the case of Al2O3/Nb. There are two kinds of bonding interfaces observed by transmission electron microscope(TEM). In addition to the directly bonded interface, an amorphous-like phase was found in some regions of the Si3N4/Ni interface. It is responsible for the degradation of bonding strength. In view of the experimental results, the existence of the amorphous-like phase in bonding interface results from the formation of SiO2 and accumulation of Al2O3 and Y2O3, which were used as sinterfng binders of Si3N4, via intergranular diffusion during the bonding process.