bluuebunny/crossref_metadata_2025 huggingface dataset:
Crystallographic Relationships between FCC and BCC Crystals: A Study Using EBSD Techniques
Authors: He You Liang , Godet Stéphane , Jacques Pascal J. , Jonas John J.
Published: March 2009

The mechanisms governing the formation of transformation textures during the austenite-to-ferrite transformation are the subject of major debate. In this study, two extreme cases were examined: those of undeformed and deformed austenite. The first involves the transformation of austenite into Widmanstätten ferrite under "equilibrium" conditions in the Gibeon iron-nickel meteorite. This meteorite passed through the transformation at the rate of a few degrees per million years. Such cooling rates cannot of course be reached under laboratory conditions. The second concerns the transformation of hot rolled austenite after a quench into the bainite temperature range. These two behaviors were investigated by means of optical microscopy and electron backscatter diffraction (EBSD) techniques. The orientations of both the parent and product phases were measured and the orientation relationships are represented in Rodrigues-Frank (R-F) space. From the orientation of a particular FCC crystal, the crystallographic orientations of the product BCC crystals can be predicted according to the Bain, Kurdjumov-Sachs (K-S) and Nishiyama- Wassermann (N-W) correspondence relationships. Comparison of the predicted and measured orientations reveals that the Bain rotation is never observed; the K-S and N-W relationships are both observed and there is a continuous distribution of orientations between the exact K-S and N-W positions. The formation of preferred orientations under non-equilibrium conditions is scrutinized. These results are compared to recent models accounting for variant selection.
On the Use of Texture Analysis and Orientation Stereology to Investigate Polycrystalline Materials
Authors: Wagner Francis , Humbert Michel , Philippe M.J. , Esling Claude
Published: March 2009

This paper focus on the use of orientation stereology to understand polycrystalline materials behavior. First some cautions or limits by using this approach are considered. Examples related to phase transformation, plastic deformation or crack propagation are then presented.
Local Orientation Gradient and Recrystallization of Deformed Copper
Authors: Field David P. , Nowell Matthew M. , Trivedi P. , Wright Stuart I. , Lillo T.M.
Published: March 2009

The texture and grain boundary structure of recrystallized materials is dependent upon the character of the deformed matrix, and the selective nucleation and growth of crystallites from the deformation structure. Proper description of the deformed matrix includes not only local crystallite lattice orientation, but also dislocation content and gradients in structural features that contribute to the heterogeneity of the nucleation and growth processes. In-situ recrystallization experiments were performed on pure copper deformed by equal channel angular extrusion, and characterization of the structure on the surface of bulk specimens was accomplished using the EBSD technique. The character of the structure where nucleation preferentially occurs is presumed to be in heavily deformed regions as nuclei were first observed in such microstructures. Grain growth is observed to
be heavily dependent upon twinning processes.
Deformation Textures in FCC Metals Subjected to Frictional and to Abrasive Wear
Authors: Schwarzer Robert A.
Published: March 2009

The surface texture in fcc metals has been investigated after wear tests in a dry-running pin-on-disk test machine and after metallographic surface grinding. X-ray pole figures have been measured at a low angle of incidence of the primary beam, using an area detector for recording the diffraction patterns. SAD pole figures have been acquired on cross sections on-line in the TEM for examining the gradient of texture and microstructure beneath the surface. The XRD and SAD pole figures have been evaluated by ODF calculation. Wear and abrasion textures are distinctly different both for copper and bronze as well as for brass.
The Effect of Texture on the Serrated Flow in Peak-Aged 2090 Al-Li Alloy
Authors: Shen Yin Zhong , Oh Kyu Hwan , Lee Dong Nyung
Published: March 2009

Tensile specimens cut from the surface layer to the center layer of a 12.7 mm thick 2090 Al-Li alloy plate were solution treated at 550°C for 30 min and subsequently peak-aged at 190°C for 18 h. They were tensile tested along the rolling direction at 25°C at various strain rates. The solution-treated specimens gave rise to serrated flows at a strain rate of 2×10-4 s-1. On the other hand, for the peak-aged alloy, the surface-layer and subsurface-layer specimens underwent complex, serrated flows (fine and coarse types superimposed each other), whereas the center-layer and near-center-layer specimens were devoid of serrated flows. The textures of the surface-layer and subsurface-layer specimens were approximated by the {001}<110> orientation, while those of the center-layer and near-center-layer specimens were approximated by the {011}<211> orientation. The different flow behaviors were discussed based on the crystallographic textures, microstructures and the strain rates.
Texture in Hot Extruded, Hot Rolled and Laser Welded Magnesium Base Alloys
Authors: Schwarzer Robert A.
Published: March 2009

In this work the textures of MgAl9Zn1, MgAl6Zn1, MgAl3Zn1 and MgAl2Mn alloys have been studied, using individual grain orientation measurement (“ACOM”) in the SEM. Hot extruded billets, unidirectional, reverse and cross-rolled sheet metals as well as laser welding seams have been investigated. In the shaft of a partial extrudate through a circular die orifice, a <0001> ring fiber texture has formed which continuously changes into a spiral fiber texture in the bottom neck. The unidirectional and the reverse hot rolled MgAl2Mn specimens show an R type <0001> texture with a small asymmetrical split whereby the basal poles are tilted by about ±12° from the sheet normal direction to the rolling direction. In the hot cross rolled specimens, the basal poles are slightly spread both in the first and second rolling directions. Texture in the laser welding seams is weak and distinctly different from that of the sheet material. There is almost no heat affected zone at the margins of the welding seams.
Effect of Cooling Condition after Warm Rolling on the Development of Microstructure and Texture in an ELC Steel
Authors: Haldar Arunansu , Ray R.K. , Khan A.J.
Published: March 2009

The microstructure and texture development in an extra low carbon steel during warm rolling (~ 80%) in a single pass at four different temperatures and at two different cooling conditions were studied. The g fibre texture develops at lower warm rolling temperatures (500 °C and 600 °C) and a very weak a fibre develops at higher rolling temperatures (700 °C and 800 °C). Very little or no difference in microstructure and texture development was observed under two cooling conditions at four rolling temperatures. No significant effect of cooling rates could be found at higher temperatures of rolling due to very fast static recrystallisation after rolling which also caused the weakening of texture. On the other hand deformation bands produced at low temperatures rolling helped in forming strong g fibre textures.
Pure Ni Single Crystal of Cube Orientation Deformed by Equal Channel Angular Extrusion
Authors: Goran D. , Fundenberger Jean-Jacques , Suwas Satyam , Bouzy Emmanuel , Tóth László S. , Skrotzki Werner , Grosdidier Thierry
Published: March 2009

Texture and microstructure were investigated after 1 pass equal channel angular extrusion (ECAE) of a single crystal cube oriented Ni billet. Neutron and X-ray diffraction were used to determine global and local textures, respectively. To investigate the fine scale microstructural features EBSD was used. Substantial variations in texture and microstructure resulting from different efficiencies in the shearing process were locally recorded through the billet height.
Texture Evolution in FCC Metals during Equal Channel Angular Extrusion (ECAE) as a Function of Stacking Fault Energy
Authors: Suwas Satyam , Tóth László S. , Fundenberger Jean-Jacques , Grosdidier Thierry , Skrotzki Werner
Published: March 2009

FCC metals with different stacking fault energy (SFE), namely Al, Cu and Ag have been investigated for the evolution of crystallographic texture during ECAE deformation using Route A. Different materials with different SFE result in their characteristic textures. The results have been analysed on the basis of microstructural features and related established concepts on texture evolution in FCC metals during other deformation modes.
Texture Evolution in Commercially Pure Al during Equal Channel Angular Extrusion (ECAE) as a Function of Processing Routes
Authors: Suwas Satyam , Tóth László S. , Fundenberger Jean-Jacques , Eberhardt André
Published: March 2009

FCC metals with different stacking fault energy (SFE), namely Al, Cu and Ag have been investigated for the evolution of crystallographic texture during ECAE deformation using Route A. Different materials with different SFE result in their characteristic textures. The results have been analysed on the basis of microstructural features and related established concepts on texture evolution in FCC metals during other deformation modes.
Quantifying Domain Textures in Lead Zirconate Titanate Using 022:202 and 220 Diffraction Peaks
Authors: Key Thomas , Jones Jacob L. , Shelley William F. , Bowman Keith J.
Published: March 2009

Determination of the domain textures in many lead zirconate titanate (PZT) piezoelectrics can be complicated by the presence of second phases, internal strains and small differences in lattice parameters for the commonly used 002 and 200:020 peaks. The domain texture is influenced by the applied polarization necessary for these materials to demonstrate piezoelectricity. In this paper we explore the use of 022:202 and 220 peaks for evaluating the domain textures and helping resolve the complexities of texture analysis in the presence of multiple phases. The two materials explored in this paper include a nominally single phase tetragonal PZT material and a mixed phase tetragonal-monoclinic lead magnesium niobate (PMN)-PZT alloy.
Effects of Dielectric Roughness on Texture of Both PVD Seed Layers and EP Copper
Authors: Kozaczek Kris J. , Murray C.E. , Rodbell K.P.
Published: March 2009

The ability to control the crystallographic orientation of both the seed layer and the electroplated copper grains is important in obtaining highly reliable Cu interconnects for ultra-large scale integration (ULSI) circuitry. One of the factors controlling film texture is the roughness of the deposition surface. In this paper the effects of dielectric roughness on the crystallographic texture of physical vapor deposited (PVD) copper seed layers and, subsequently, on the texture of electroplated (EP) copper have been investigated. Six relevant interlevel dielectric materials were examined: tetraethyloorthosilicate (TEOS), borophosphosilicate glass (BPSG), silane oxide, silicon nitride, SiLKTM (from the Dow Chemical Corporation), and polysilicon were deposited on 200 mm (001) Si wafers. The RMS surface roughness of these dielectric layers, measured by AFM, ranged from 0.32 nm to 20.51 nm. Texture was analyzed on a dedicated x-ray diffractometer equipped with a two dimensional detector collecting incomplete pole figures with a 1.0 degree resolution in pole figure space. The orientation distribution functions (ODF) were calculated using the arbitrary defined cells method and the volume fractions of major fiber texture components were derived from the ODF. The predominant texture components of the PVD and EP copper were (111) and (511) fiber. It was found that the volume fraction of (111) fiber decreased as the dielectric surface roughness increased. One exception was with the SiLKTM dielectric, which produced significantly weaker texture than other dielectrics with similar surface roughness. The copper films deposited on polysilicon, which possessed the roughest deposition surface of all the dielectric films had a random
texture. Finally, a mixture of strong (111) and (511) fiber textures of EP copper was achieved on dielectric underlayers with smoother surfaces. The results demonstrate that the deposition surface roughness plays an important role in establishing the texture in overlying PVD and EP Cu films. The texture of PVD and EP copper may serve as a useful indicator of the underlayer roughness.
Micro-Diffraction Studies of the Evolution of Textures in CVD-Grown Diamond Films
Authors: te Nijenhuis J. , Fransen M.J. , Vasterink J.H.A.
Published: March 2009

In this study a detailed analysis is given of the development of preferred orientations of polycrystalline diamond films, deposited from the gas phase using the combustion-flame assisted chemical vapor deposition technique, as a function of the amount of intentionally added nitrogen. The preferred orientations are studied using X-ray diffraction and are compared with the morphological changes of the sample surfaces. The role of nitrogen in the deposition process is discussed. Low amounts of nitrogen enhance the growth rate and lead from a randomly oriented layer successively to {011} and {001} fiber textures. Higher amounts of nitrogen deteriorate the growth; no preferred orientation is visible anymore.
Texture Analysis of Poly(vinyl Chloride) Foils
Authors: Kalvoda Ladislav , Dlouhá Maja , Vratislav Stanislav , Lukáš R. , Gilbert Marianne
Published: March 2009

The crystallographic textures of the free-standing diamond films which were synthesized by the chemical vapor deposition (CVD) using a CH4/H2/Ar gas mixtures have been investigated. Texture components of the diamond films are analyzed with pole figures and orientation distribution function (ODF). The surface morphology of the diamond films grown at different substrate temperatures as well as different gas concentrations is observed with scanning electron microscopy.(SEM). The experimental results indicate that the intensity of {110} fibre texture becomes much higher with the increase of the substrate temperature. It is considered that the higher multiplicity of <110> crystallographic direction in diamond octahedron leads to the higher appearance possibility of {110} fibre texture and the final texture components of the diamond films depend upon the CVD deposition parameters.
Textures of Ferroelectric BLT Films for Semiconductor Memories by Electron Backscatter Diffraction and Piezo-Response Force Microscope
Authors: Yang B. , Park No Jin , Kim Sung Jin , Hong Suk Kyoung
Published: March 2009

Issues of ferroelectric high-density memories (>64Mb) indispensable for upcoming ubiquitous era have been on the cell integration less than 0.1um2 and reliabilities. Thus nanoscale control of microstructures of ferroelectric films with large switching polarization has been one of the issues to obtain the uniform electrical properties for realization of high-density memories. In this study the grain orientations and distributions of BT-based films by spin-on coatings were examined
by EBSD (electron backscatter diffraction) technique. Ferroelectric domain characteristics by PFM (piezo-response force microscope) were also performed to study the dependence of reliabilities on the grain orientations and distributions. It is believed that understandings of the nucleation and growth mechanisms of the a- or b-axis oriented films during the thermal processes such as RTA and furnace annealing affecting on grain orientation and uniformity could be possible based on this experimental results.
In Situ Texture Analysis Using Hard X-Rays
Authors: Brokmeier Heinz Günter , Yi Sang Bong , Park No Jin , Homeyer Jens
Published: March 2009

Due to the high penetration power, the high photon flux and the excellent brilliance high energetic synchrotron radiations are a phantastic tool particular in fast experimentation. Therefore in-situ measurements under applied load or at various temperatures have been carried out to investigate the texture influence on the deformation of magnesium and aluminium. An upgraded loading device with a power up to 20 kN was installed at the hard wiggler beamline BW5. Magnesium samples with different initial textures show the strong influence on this texture on the activation of different glide systems and on the activation of twins. First experiments to study the phase transition in titanium were performed, which demonstrate the strong orientation correlation between the α- and the β-phase.
Self-Organization and Dynamic Characteristics Study of Nanostructured Liquid Crystal Compounds
Authors: Kamanina Natalie V. , Zubtsova Yu.A. , Shulev V.A. , Mikhailova M.M. , Denisyuk A.I. , Butyanov S.V. , Murashov S.V. , Sapurina I.Yu.
Published: March 2009

Fullerene-doped liquid crystal compounds have been considered as new nanostructured materials with promising photosensitivity and speed parameters. Self-organization in liquid crystal mesophase based on charge-transfer complexes between an organic donor and fullerene has been investigated. The switch-on time of 50 μs has been obtained. The results are discussed from the viewpoint of increasing the system polarizability and a possible transition from the nematic phase to the smectic one, which is caused by a complex formation.
Microstructure and Mechanical Properties of Spark Plasma Sintered ZrO2-Al2O3-TiC0.5N0.5 Nanocomposites
Authors: Vanmeensel Kim , Sastry K.Y. , Hennicke J. , Anné Guy , Jiang Dongtao , Laptev A.I. , Vleugels Jef , Van der Biest Omer
Published: March 2009

Future materials for wear resistant components require a combination of excellent mechanical properties such as hardness and toughness, short processing times and good electrical conductivity to facilitate shaping by electro discharge machining (EDM). In this work, the hardness and fracture toughness of t-ZrO2 based electro conductive composites was optimised, while short processing times below 20 minutes using spark plasma sintering were sufficient to obtain near fully dense materials. The influence of powder processing technique using TiC0.5N0.5 as the starting powder and yttria as a stabiliser on the mechanical properties of ZrO2-TiC0.5N0.5-Al2O3 based composites was investigated. Fully dense Y-TZP based composites possessed an excellent toughness of 9.2 MPa.m1/2 and an increased Vickers hardness of 1397 kg/mm².
Precipitation of Nickel Hydroxides from Nickel Dodecylsulphate
Authors: Coudun C. , Hochepied Jean-François
Published: March 2009

Classical precipitation techniques applied to a nickel di-dodecylsulphate Ni(DS)2 precursor were developed. In the range of concentrations studied this precursor forms direct micelles in water. In pH-controlled double jet precipitation with soda at 60°C, the pure a, poorly crystallised bbc and well crystallised b phases are successively obtained by pH shifts from 8 to 11, whereas the platelet morphology remains similar. In the same conditions, classical salts never lead to a phase and the particle size and morphology is pH dependent. Hydroxide precipitation by ammonia decomplexation, via heating at 60°C, Ni(DS)2 leads to well-calibrated stacks of b- Ni(OH)2 nanopancakes (300 nm in diameter and 200 nm stacking length) whereas classical salts lead to micrometric particles characterised by thin interconnected walls.
Hybrid HAp-Maleic Anhydride Copolymer Nanocomposites Obtained by In Situ Functionalisation
Authors: Piticescu Roxana M. , Chitanu Gabrielle Charlotte , Albulescu Mihaela , Giurginca Maria , Popescu Madalina Laura , Łojkowski Witold
Published: March 2009

The aim of the work is to establish if maleic anhydride copolymer acts as a grain growth modulator and/or as a biocompatible functionalisation agent for hydroxyapatite. Experimental work was developed in three directions: nanocomposites synthesis, nanocomposites characterization and citotoxicity tests on nanocomposites. Maleic anhydride copolymer – HAp nanocomposites were prepared by in situ functionalisation in hydrothermal conditions and were characterized by chemical quantitative analysis, XRD, FT-IR, SEM, specific surface area and picnometric densities. Chemical bonding between the copolymer carboxyl groups and calcium ions of HAp induced a peak of 1577 cm-1 on the FT-IR analysis. Following the evolution of this characteristic peak with the hydrothermal synthesis conditions (different temperatures and pressures) and corroborates the results with XRD and SEM analysis it was pointed out the copolymer grain growth modulator behaviour. Citotoxicity studies in vitro on mice fibroblast cultures were performed. The results proved the biocompatibility of new hybrid –polymer nanocomposites.
X-Rays at the SIAM Photon Source
Authors: Apiwatwaja R. , Chunjarean S. , Hass K. , Hoyes G. , Kaewprasert C. , Klysubun P. , Klysubun W. , Pairsuwan W. , Rugmai S. , Rujirawat Saroj , Sanguansak N. , Songsiriritthigul P. , Wiedemann H.
Published: March 2009

In this note, we describe the upgrade effort to convert the SIAM Photon source into an Xray synchrotron radiation facility with photon energies up to some 15 keV. This conversion of SIAM Photon into a third generation light source can be achieved through an increase of the electron beam energy and the addition of recently available superconducting wavelength shifter and multipole wiggler magnets. A gradual retrofit of vacuum chambers aiming at a reduction of electron beam instabilities as well as a modification of the focusing structure are expected to greatly increase the brightness of the photon beam. These upgrades will be implemented gradually over a few years to minimize the interruption of ongoing experimental activities. As an ultimate upgrade, a study has been started which shows the feasibility to implement a 2 GeV storage ring replacing the present ring in the same foot print. This new ring is configured to provide double the number of insertion device photon beam lines.
Anti-Corrosion Properties of Nitrogen and Oxygen Plasma-Implanted Nickel-Titanium Shape Memory Alloy
Authors: Ho J.P.Y. , Poon R.W.Y. , Xie Y.T. , Ha P.C.T. , Chu Paul K.
Published: March 2009

Nickel-titanium shape memory alloys (NiTi) have potential applications as orthopedic implants but out-diffusion of harmful Ni from the NiTi substrate during prolonged use inside a human body is a serious issue and the problem must be solved before the materials can be more widely used in orthopedics. In this work, we produce TiN and TiOx barrier layers by plasma immersion ion implantation (PIII) and study the effects of different working voltages (20kV, 30kV, and 40kV). The corrosion resistance of the plasma-treated materials is found to be much improved and the optimal processing windows are described in this paper.
Effect of Oxygen Precipitates on the Surface-Precipitation of Nickel on Cz-Silicon Wafers
Authors: Nakamura Kozo , Tomioka Junsuke
Published: March 2009

This paper presents a model for the analysis of the surface nucleation and growth of Ni silicide on silicon wafers contaminated by Ni. The model can additionally be used to characterize the gettering reaction of Ni induced by oxygen precipitates. We also discuss the relation between the surface precipitation of Ni silicide and the gettering ability of oxygen precipitate. The surface precipitation of Ni silicide depends on the total surface area of oxide precipitates. When the total surface area of the oxide precipitates exceeds the critical value, the surface precipitation is rapidly suppressed. Our model can explain the phenomenon of the gettering threshold in the following manner. 1) The gettering of Ni by oxygen precipitates is a reaction-limited process at the interface between oxygen precipitate and silicon, as Sueoka proposed. 2) The residual Ni concentration in this reaction-limited gettering process continuously decreases as the total surface area of the oxide precipitates increases. 3) The surface precipitation of Ni silicide is rapidly suppressed when the residual Ni concentration falls below the critical concentration. Our calculation results correspond well with the experimental results.
Microscopic Mechanisms of Cobalt Disilicide Nucleation in Silicon
Authors: Borodin V.A. , Ruault M.O. , Ganchenkova Mariya G. , Fortuna F.
Published: March 2009

The paper presents the results of experimental in-situ observations of cobalt disilicide nucleation in Co+ implanted silicon and ab initio simulations of energies of small cobalt and cobaltvacancy clusters. Based on these results, microscopic nucleation mechanisms of different types of CoSi2 precipitates are discussed.
Effect of Hydrogenation on Defect Reactions in Silicon Particle Detectors
Authors: Makarenko L.F. , Korshunov F.P. , Lastovski S.B. , Lastovskii Stanislav B. , Kazuchits N.M. , Rusetsky M.S. , Fretwurst Eckhart , Lindström G. , Moll Michael , Pintilie Ioana , Zamiatin N.I.
Published: March 2009

The influence of preliminary treatment in hydrogen plasma on elimination of radiation defects and formation of thermal donors has been studied in detector structures made of standard and oxygenated float zone silicon has been studied. A new type of thermal donors has been found in as-treated diodes. These thermal donors are unstable and can be eliminated by heat-treatment at 200-250°C. After irradiation with 3.5 MeV electrons the detectors had been annealed at temperatures of 50-350 °C. It has been found that preliminary hydrogenation at 300 °C leads to disappearance of main vacancy-type radiation defects at lower annealing temperatures. The annealing of hydrogenated and irradiated crystals is accompanied by hydrogen redistribution and formation of hydrogen-related donors. Preliminary irradiation influences on both these processes.
Quantum-Chemical Simulation of Silicon Grain Boundaries Contaminated by Oxygen and Carbon
Authors: Saad Anis M. , Pushkarchuk Alex L. , Mazanik A.V. , Fedotov A.K. , Kuten S.A.
Published: March 2009

Transformation of the “core” atomic structure and electronic states of the tilt Σ5 θ = 37° [001]/(130) grain boundary in poly-Si due to incorporation of carbon atoms into the oxygencontaining complexes is studied using MM and MO LCAO methods. Different numbers n = 1 ÷ 4 of C-atoms were introduced into the 5-fold interstitial positions in the initial O-containing complexes built-up from SiO3 and SiO4 configurations at the GB “core”. Incorporation of C-atoms into SiO3 and SiO4 complexes leads to the formation of Si-O-C-Si chains and shifting of the donorlike levels generated by SiO3 and SiO4 configurations to the bottom of the conduction band with an increase in the number of the incorporated C-atoms.
On the Electrical Activity of Misfit and Threading Dislocations in p-n Junctions Fabricated in Thin Strain-Relaxed Buffer Layers
Authors: Simoen Eddy , Eneman G. , Shamuilia Sheron , Simons V. , Gaubas Eugenijus , Delhougne R. , Loo R. , De Meyer K. , Claeys Cor
Published: March 2009

The electrical activity of threading dislocations (TDs), occurring in a thin SiGe Strain Relaxed Buffer (SRB) layer has been investigated by a number of techniques and its impact on the reverse current of p-n junction diodes has been evaluated. It is shown that besides the density of TD, there are at least two other parameters playing an important role. The distance with respect to the metallurgical junction of the 5 nm C-rich layer, used for the strain relaxation and the dopant type in the well region also affect the leakage current. This complex behaviour is further reflected in the Emission Microscopy (EMMI) images, showing different breakdown sites for p+/n or n+/p junctions. Results will be presented whereby one of these parameters is varied, while the others are kept constant, in order to arrive at some idea of the relative importance of the different factors.
Structure Determination of Clusters Formed in Ultra-Low Energy High-Dose Implanted Silicon
Authors: Cherkashin N. , Hÿtch Martin J. , Cristiano Fuccio , Claverie A.
Published: March 2009

In this work, we present a detailed structural characterization of the defects formed after 0.5 keV B+ implantation into Si to a dose of 1x1015 ions/cm2 and annealed at 650°C and 750°C during different times up to 160 s. The clusters were characterized by making use of Weak Beam and High Resolution Transmission Electron Microscopy (HRTEM) imaging. They are found to be platelets of several nanometer size with (001) habit plane. Conventional TEM procedure based on defect contrast behavior was applied to determine the directions of their Burger’s vectors. Geometric Phase Analysis of HRTEM images was used to measure the displacement field around these objects and, thus, to unambiguously determine their Burger’s vectors. Finally five types of dislocation loops lying on (001) plane are marked out: with ] 001 [1/3 ≅ b and b ∝ [1 0 1], [-1 0 1], [0 1 1], [0 -1 1].
Passivation of Ge Nanocrystals in SiO2
Authors: Jensen Jesper Skov , Leervad Pedersen Tom P. , Pereira Rui , Bomholt Pia , Chevallier Jacques , Hansen Ole , Larsen Arne Nylandsted , Nielsen Brian Bech
Published: March 2009

Nanocrystals have attracted considerable attention in recent years because of their potential applications as a light source in Si technology. From theory Ge nanocrystals are expected to have better luminescence properties than Si nanocrystals. In this study we have compared Ge nanocrystals produced both in PE-CVD deposited and magnetron sputtered SiO2 doped with Ge during deposition to concentrations between 3-9 at.%, followed by high temperature treatment at temperatures between 600 and 1100°C. The nanocrystals were structurally characterized by Rutherford backscattering spectrometry (RBS), transmission electron microscopy (TEM) and electron paramagnetic resonance (EPR). The interface of the nanocrystals was passivated by use of alnealing, while the effect of the passivation was monitored by photoluminescence (PL)
Stress - Dependent Out - Annealing of Defects in Self - Implanted Silicon
Authors: Misiuk Andrzej , Surma Barbara , Bak-Misiuk Jadwiga
Published: March 2009

Effect of hydrostatic pressure (HP) on out – annealing of defects in self – implanted silicon (Si:Si, Si+ doses 5x1016 cm-2 and 1x1017 cm-2, energies 50 keV and 160 keV), treated for 1 – 10 h at up to 1400 K (HT) under HP ≤ 1.4 GPa, has been investigated by photoluminescence, X-ray and related methods.
Applied at 720 – 1270 K enhanced pressure does not affect or affects adversely Si:Si structure while at 1400 K assists in its improvement. HP – dependent transformations in Si:Si at HT are related to effect of HP on diffusion of point defects, such as silicon interstitials and vacancies produced at implantation. Out - annealing of defects in self - implanted silicon is dependent also on spatial position of damaged areas in Si substrate.
Quantum Well Related Conductivity and Deep Traps in SiGe/Si Structures
Authors: Antonova I.V. , Golik L.L. , Kagan M.S. , Polyakov V.I. , Rukavischnikov A.I. , Rossukanyi N.M. , Kolodzey J.
Published: March 2009

Electrical transport and traps in vertical SiGe/Si QW structures of low background doping level are studied in the presented report. Temperature activation of holes from the quantum well was found to determine the vertical current through Si/SiGe/Si structures at T > 160 K. At lower temperatures (T < 130 K), the current mechanism is attributed to a thermally activated tunneling of holes from quantum well. Deep traps are observed in the Si/SiGe/Si structures in high concentration (1011 – 1012 cm-2). Traps are most likely assistance in the current in the vertical Si/SiGe/Si structures as recombination centers near the QW.
Laser Assisted Formation on Nanocrystals in Plasma-Chemical Deposited SiNx Films
Authors: Arzhannikova Sofia A. , Efremov M.D. , Volodin Vladimir A. , Kamaev G.N. , Marin D.V. , Soldatenkov S.A. , Shevchuk V.S. , Kochubei S.A. , Popov A.A. , Minakov Yu. A.
Published: March 2009

The laser assisted formation of silicon nanocrystals in SiNx films deposited on quartz and silicon substrates is studied. The Raman spectroscopy revealed creation of the Si cluster and crystallite after excimer laser treatments. Photoluminescence signal from the samples was detected at room temperatures. I-V and C-V measurements were carried out to examine carries transfer through dielectrics film as well as recharging of electronics states.
Potential and Limitations of Electron Holography in Silicon Research
Authors: Formanek Peter , Kittler Martin
Published: March 2009

We report on electron holography as a promising candidate for diagnostics in silicon technology and research. Electron holography determines the local phase shift of the electron wave passing through a sample. The phase is proportional to the 2D projected electrostatic potential in the sample and thus reveals p-n junctions and, indirectly, doping. We demonstrate detection of submonolayer boron layers in Si and SiGe, measurement of Ge concentration in SiGe and qualitative 2D oxygen mapping in SiO2/Si structures with 0.5 nm resolution, and comparison of doping in two bipolar transistors with different base implant. Resolution and noise limits are discussed.
Infrared Absorption Measurement of Carbon Concentration down to 1x1014/cm3 in CZ Silicon
Authors: Inoue N. , Nakatsu M.
Published: March 2009

Measurement of carbon concentration in CZ silicon by infrared absorption spectroscopy was examined. Noise level was suppressed down to 10-4 in unit of absorbance. Residual differential absorption between the sample and reference was removed by fitting the phonon absorption spectrum to the background absorption spectrum. The effect of narrowing of absorption spectral range was examined. As a result, it was possible to measure the differential carbon concentration down to about 1×1014/cm3. Measurement of commercial wafer was also established.
EBIC Study of Electrical Activity of Stacking Faults in Multicrystalline Sheet Silicon
Authors: Lu Jinggang , Rozgonyi George A. , Rand James , Jonczyk Ralf
Published: March 2009

The electrical activity of stacking faults (SFs) in multicrystalline sheet silicon has been examined by correlating EBIC(electron beam induced current), preferential defect etching, and microwave photo-conductance decay (PCD) lifetime measurements. Following a three hour 1060 0C annealing the interstitial oxygen concentration decreased from 14 to 4.5 x 1017 cm-3, during which time a high density of SFs were generated in the center of individual large grains. Subsequent EBIC contrast variation within individual large grains was correlated with the local SF density revealed by preferential etching. In addition, a more quantitative intra-grain lifetime was obtained from high spatial resolution PCD measurements. It was found that an SF density of 1 to 2 x 106 cm-2 produces a lifetime limitation in sheet silicon which corresponds to a recombination lifetime of ~2 µs.
Measurement of Oi in Heavily Boron Doped Chemical Thinned Silicon by Low Temperature FTIR Spectroscopy
Authors: Zschorsch Markus , Gärtner G. , Möller Hans Joachim , von Ammon Wilfried
Published: March 2009

The content of interstitially solved oxygen (Oi) in heavily boron doped silicon (9- 29 mcm) were measured by low temperature Fourier transform infrared (FTIR) spectroscopy. Therefor an alternative thinning technique for silicon is used: by alkaline potassium hydroxide etching (KOH) prepolished silicon specimens are thinned down to 8 - 60 microns. The optimal end thickness depends on the boron concentration which specifies the free carrier concentration. Specimens with three different boron concentrations (9/19/29 mcm) were examined. The results are compared with gas fusion analysis (GFA) measurements. Furthermore the precipitated oxygen Oi was measured for a RTA process (20s@1250°C) with subsequent growth steps (4h@780°C + 16h@1000°C).
Electrical Characterizations of Hydrogenated 4H-SiC Epitaxial Samples
Authors: Ottaviani Laurent , Barakel Damien , Vervisch Vanessa , Pasquinelli Marcel
Published: March 2009

4H-SiC epitaxial layers were hydrogenated by means of plasma treatment and annealing, aiming at passivating the surface by forming bonds with Si atoms. Ni/SiC Schottky contacts were processed, and investigated by electrical methods (I-V-T, C-V-T, EBIC, DLTS). The annealings were performed at two different temperatures (300°C and 400°C) in H2 ambient. The Inductively Coupled Plasma (ICP) treatment was effected before and after the Schottky contact metallization, and two integrated hydrogen doses were imposed for the same low energy (500 eV/atom). Two deep levels were detected in the gap of the sample hydrogenated at the highest dose before contact deposition, similar to the double defect RD1/2 associated to the vacancy pair VSi-VC. No deep level was found on other plasma-hydrogenated samples, which electrical characteristics are the same than for virgin SiC. A slight improvement of electrical parameters (lowering of ideality factor, increasing of minority carrier diffusion length, better switching behaviour) was only measured on the sample annealed at 400°C.
Calibration Factor for Determination of Interstitial Oxygen Concentration in Germanium by Infrared Absorption
Authors: Litvinov Valentin V. , Svensson Bengt Gunnar , Murin L.I. , Lindström J. Lennart , Markevich Vladimir P.
Published: March 2009

Intensities of infrared absorption due to asymmetric stretching vibrations of interstitial oxygen atoms in Ge crystals enriched with 16O and 18O isotopes have been compared with oxygen concentrations determined by means of secondary ion mass spectrometry (SIMS). For Ge samples with oxygen content less than 5⋅1017 cm-3 a good correlation has been found between the values of oxygen concentration and values of absorption coefficient in maximum of the absorption band at 855.6 cm-1 with a proportionality coefficient CO = 0.95.1017 сm-2. It is argued that kinetics of oxygen-related thermal double donor formation and oxygen loss upon heat-treatments of Ge crystals at 350 оС cannot be described properly with the application of calibration coefficient CO = 5.1016 cm-2, which is widely used for the determination of oxygen concentration in Ge crystals.
SiGe Light-Emitting Diodes and Their Characteristics in the Region of Band-to-Band Transitions
Authors: Emel'yanov A.M. , Sobolev N.A. , Mel'nikova T.M. , Abrosimov Nikolay V.
Published: March 2009

Light-emitting diodes (LEDs) based on single crystal SiGe with the Ge content of 5.2% were fabricated using a planar technology. Their electroluminescence (EL) parameters were studied over a wide range of measured currents (up to 11 A) and temperatures (80 - 300) K. The integrated EL intensity at a fixed current increased approximately two times with temperature increasing from 80 to 200 K and changed insignificantly in the temperature range of 200 – 300 K. The analysis of the EL spectra shows that the recombination involving excitons is the dominant mechanism of radiative recombination at both no-phonon and phonon-assisted transitions in SiGe LEDs not only at low temperature but at room temperature, too. The linear dependence of the integrated EL intensity on the current and the exponential decay of the integrated EL intensity confirm this conclusion. The room temperature internal quantum efficiency of EL in the region of band-to-band transitions is estimated to be 0.5%. A sublinear current dependence of the integrated EL intensity and a fast decay of the integrated EL intensity after the diode turn-off were observed at room temperature and currents > 2.5 A. The effect is associated with the appearance of an additional (Auger) mechanism of non-radiative recombination parallel to Shockley-Read-Hall recombination.
Fine Structure of Dislocation Related PL Bands D1 and D2 in Silicon
Authors: Steinman E.A. , Tereshchenko A.N. , Orlov Valeri I. , Kirscht F.G.
Published: March 2009

The samples of p- and n-doped Fz Si were deformed in 3-point bending mode in the temperature range 800-950°C. The fine structure of dislocation related luminescence in the region of D1 and D2 bands was most pronounced at lowest rate of deformation. The temperature variation of intensity of individual lines did not reveal any thermalization effects. It implies that centers responsible for different individual lines are situated in diverse places. The most narrow lines with maximum positions of 802 meV and 807 meV (D1 band) and 869 meV and 873 meV (D2 band) are rapidly quenched with increase in temperature, while the broader background lines survive at higher temperature. The new line with maximum position at about 882 meV appears in the D2 band with enhanced carbon doping. It was found that at higher P-doping the low energy fine structure lines 802 meV and 869 meV are absent. Besides, the Fz samples with different P doping level from 6×1014 cm-3 to 1.2×1016 cm-3 demonstrate quite a different temperature variation of broad background lines. At lowest level of P-doping they move to low energy side at temperature above 30K, while at P-doping above 1015 cm-3 these lines move to higher energy in the same temperature range. A possible explanation of this observation can be related to distribution of electrons in the cband. It implies that the corresponding electronic transitions occur between the edge of conduction band and deep states.
Evaluation of CVD Diamond Coating Using Back-Reflected Rayleigh Surface Wave
Authors: Kim Young H. , Song Sung Jin , Kwon Sung Duk , Takagi Toshiyuki , Uchimoto Tetsuya , Abe Toshihiko
Published: March 2009

The propagation characteristics of the back-reflected Rayleigh surface wave in chemical vapor deposit (CVD) diamond coated specimens were investigated experimentally using the ultrasonic backward radiation measurement. The deliberated delaminations produced between the coating layer and the substrate decreased Rayleigh surface wave velocity. This initial experimental
result obtained in the present study demonstrates the high potential of the backward radiated ultrasound as a tool for nondestructive evaluation of very thin CVD diamond coating layer.
Calculation of Radiation Beam Field from Phased Array Ultrasonic Transducers Using Expanded Multi-Gaussian Beam Model
Authors: Park Joon Soo , Song Sung Jin , Kim Hak Joon
Published: March 2009

For the reliable application of ultrasonic phased array technique, it is necessary to
understand the characteristics of the radiation beam field from the array transducers quantitatively. Very recently, it has been developed the expanded multi-Gaussian beam model that can calculate the radiation beam field from a single, rectangular transducer with great computational efficiency. In this
paper, this model is adopted to calculate the radiation beam field from array transducers with various time delays to achieve steering and/or focusing. The calculation results are compared to those obtained by well known Rayleigh-Sommerfeld integral that provides the exact solution in order to explore the validity of the expanded multi-Gaussian beam model in this task.
Cleavage Fracture Evaluation Using Local Approach for SA508 Carbon Steel at -60°C
Authors: Chang Yoon Suk , Lee T.R. , Choi Jae Boong , Kim Young Jin , Lee Bong Sang
Published: March 2009

The scatter of measured fracture toughness data and transferability problems for specimens with different crack configurations and loading conditions are major obstacles for integrity assessment of ferritic steels in ductile-brittle transition region. To address these issues, recently, concerns for local approach adopting micro-mechanical damage models are being increased again in connection with a progress of computational technology. In this paper, cleavage fracture evaluation based on Weibull statistics was carried out for SA508 carbon steel. A series of three dimensional finite element analyses as well as corresponding fracture toughness tests were performed for 1T-CT and PCVN specimens at -60°C. Also, failure probability analyses for different configurations and sensitivity analyses for Weibull parameters were conducted. Thereby, promising results have been derived through comparison between measured and estimated fracture toughness data, which can be utilized to make the basis for demonstrating real safety margins of components containing defect.
Preparation and Optical Properties of Thin-Films of Layered Perovskite-Type Hybrid Compounds (CnH2n+1 NH3)2 PbX4
Authors: Shi K.Y. , Guo L.L. , Liu H.X. , Zou L. , Ying S.F.
Published: March 2009

Thin films of organic-inorganic hybrids (CnH2n+1NH3)2PbX4(X=Cl, Br, I; n=4,6,8,10) were prepared by the spin-coating method. The influences of annealing temperature on the crystal structure of the films were analyzed by X-ray diffraction(XRD). The surface morphology of the films were observed using scanning electronic microscope(SEM). The room-temperature UV-Vis absorption spectra of the films were employed to examine the effect on the optical properties of
different elements X (X=Cl,Br,I), and varying n from 4 to 10, respectively. The results showed that a significant red shift of the absorption peak was observed for different X in inorganic layers, and the position of the exciton absorption peaks did not shift obviously with the increasing of the alkyl chain length in organic layers. The results suggested that the exciton absorption arise from electronic transitions within the inorganic layer, rather than from the organic layer.
Fuzzy Hybrid Controller Model for Making Decision to Interpret Any Condition
Authors: Karim M. Shahidul , Mustafa Rashed
Published: March 2009

The constantly increasing performance/price ratio of microcontrollers means electronic system can replace more and more electromechanical ones. In design, the goal is not to just replace the solution but also to improve it by adding new functionalities. The paper presents a model of industrial controller having possibility of the classical programming controller, with added elements of the fuzzy logic. Here fuzzy logic offers a technical control strategy that uses elements of
everyday language. In this application, it is used to design a control strategy that adapts to the need of individual user. It achieves a higher comfort level and reduces energy consumption. Here we have used a fuzzy method which selects the contractions that best meet the specifications, where human knowledge is involved in a decision making process. With a fuzzy-logic software development system, the entire system, which includes conventional code for signal preprocessing
as well as the fuzzy logic system, can be implemented on an industry-standard microcontroller. Using fuzzy logic on such a low-cost platform makes this a possible solution with most AC systems. Each home AC has a sensor that measures room temperature and compares it with the temperature set on the dial. The fuzzy logic controller uses a bimetallic switch and compares the set temperature with room temperature.
Sol-Gel Synthesis and Structure-Property Relations in ZnxCu1-xBi2O4 (0≤ x ≤0.6) Spinels
Authors: Das B.B. , Lathabai D.
Published: March 2009

Studies on ZnxCu1-xBi2O4(0≤ x ≤0.6) spinels (S1-S5: x = 0.0, 0.15, 0.3, 0.45, 0.6) were done using varieties of structure sensitive techniques. The powder X-ray diffraction (XRD) studies shows formation of cubic phase, a=10.6023 Ǻ, space group, Ia3, Z=3 in all the samples. The IR spectral results show the presence of octahedral[CuO6/2] or [BiO6/2] units and Bi-O, Cu-O, and Zn-O bonds in the samples. From the trend g║>g┴>ge(ge=2.0023) obtained from electron paramagnetic resonance(EPR) lineshapes simulation we conclude that the paramagnetic site in these glasses is Cu2+(3d9) which is in a tetragonally elongated octahedron [O1/2-CuO4/2-O1/2] exhibiting Jahn-Teller distortion having D4h symmetry with orbital singlet 3dx 2-y 2(2B1g) as the ground state.