bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of as Overpressure on Mn-Induced Layer Disordering in AlGaAs-GaAs Superlattices: An Investigation of the Mn Diffusion Mechanism
Authors: Wu C. H. , Maun J. I. , Hseh K. C. 
Published: March 2011

ABSTRACTData are presented showing the effect of As overpressure on the diffusion of Mn into an AlGaAs-GaAs superlattice (SL) using MnAs as the diffusion source. Arsenic overpressure has been shown to play a significant role in both impurity-induced layer disordering (IILD) and the microstructure of the Mn-diffused samples. The degree to which layer disordering occurs decreases as As overpressure increases. Furthermore, dislocation loops are observed for the diffusion of Mn under Ga-rich conditions at prolonged diffusion times. Both results, in addition to the effect of As overpressure on the Mn diffusion profile, indicate that Mn diffusion into GaAs or GaAs-AlGaAs heterostructures takes place by an interstitial-substitutional mechanism involving column III vacancies under As-rich conditions and a “kick-out” mechanism involving column III interstitials under Ga-rich conditions.
Heteropolytype Growth of Beta Silicon Carbide on Alpha Silicon Carbide by Low Pressure Chemical Vapor Deposition at 1150 C
Authors: Irvine K. J. , Spencer M. G. , Dmitriev V. A. 
Published: March 2011

ABSTRACTWe report on the low temperature growth of heteropolytype junctions of 3C-SiC on 6H-SiC by low pressure chemical vapor deposition. In this work we have observed the epitaxial layers to be single crystal below a critical thickness limit which depends on growth temperature. Films thicker than this limit are polycrystalline. At 1150 C we have found the critical thickness to be approximately 2500 angstroms.
An Overview of Plasma Processing
Authors: Szekely Julian 
Published: March 2011

ABSTRACTAn overview is presented of the plasma processing of materials. The principal components of this overview include the definition and classification of plasmas of interest in materials processing, the methods of plasma generation and the basic engineering principles that govern plasma phenomena. Here emphasis is placed on both plasma theory and on the experimental verification of the models. This is followed by a brief description of principal plasma applications, including thermal plasmas used in melting, refining, plasma deposition and plasma synthesis and low pressure plasmas used in synthesis and in the processing of electronic materials.The review is concluded by a brief discussion of future prospects for plasma technology, where the main developments envisioned are in the area of improved coatings, the processing of electronic materials, melting and refining of refractory metals and superalloys and finally the possibility of more widespread use for plasma systems in extractive metallurgy.
Heat Transfer Analysis of the Plasma Sintering Process
Authors: Pfender E. , Lee Y.C. 
Published: March 2011

ABSTRACTIn the process of r.f. plasma sintering of Al2O3 at reduced pressure, a number of puzzling observations have been reported. They include higher heating rates and higher maximum temperature of a sample at increased propagation velocities of the sample through the plasma and a sudden temperature drop of approximately 700°C if the sample motion in the plasma is stopped. An analysis of the sintering process indicates that the change of che surface area and of the catalytic properties of the sample surface during sintering seem to be responsible for these observations. The change from an initially negatively charged co an essentially non-charged surface causes a drastic decrease of the heat transfer from the plasma to the sample. A simulation of the plasma sintering process based on a r.f. argon plasma provides a semi-quancicative explanation of all the observed phenomena.
Multiple Arc Discharges for Metallurgical Reduction or Metal Melting
Authors: Harry J.E. , Knight R. 
Published: March 2011

ABSTRACTMultiple arc discharges enable more than one arc to be operated in close proximity supplied from the same supply. This enables reduced individual electrode current to be used. Multiple electrodes may be used in d.c. arc furnaces and d.c. plasma furnaces for melting, liquid-phase smelting and particulate phase processes. Non-consumable multiple electrodes may be used to replace graphite electrodes in arc furnaces. Other applications include high temperature gas heating and in flight plasma reactions.
Plasma Arc Carbide Coatings on Titanium
Authors: Shull R. D. , Boyer P. A. , Ives L. K. , Bhansali K. J. 
Published: March 2011

ABSTRACTThe plasma transferred arc (PTA) process has been traditionally used to deposit wear resistant coatings on iron base alloy substrates, but has not been employed to coat lightweight alloys due to processing problems. In the current study, use of the PTA process to deposit TiC, WC, and Cr3C2 coatings on titanium substrates has been explored. The resistance of these coatings to dry abrasive wear has been measured and compared to that of the base metal. The variation in wear resistance of these coatings is discussed in terms of the carbide particle size and the microstructure of the deposit. A comparison is also made to coatings prepared by a laser surface melting and carbide particle injection process.
Modelling of Plasma Processes
Authors: Boulos Maher I. 
Published: March 2011

ABSTRACTA review is made of some of the mathematical modelling work carried out over the last few years with the objective of computing the flow and temperature fields for different thermal plasma systems. Typical results are given for d.c. plasma jets, transfered and non-transfered arc plasma reactors and for inductively coupled plasma torches. This is followed by a brief discussion of the important problem of plasma-particle heat transfer.
Electrical and Optical Properties of Yb, Er doped GaAs
Authors: Benyattou T. , Seghier D. , Brémond G. , Moneger S. , Kalboussi A. , Marrakchi G. , Guillot G. , Lhomer C. , Lambert B. , Toudic Y. , Le Corre A. 
Published: March 2011

ABSTRACTIn this paper we report results from electrical and optical measurements carried out on GaAs:Yb, Er.For GaAs:Yb electrical experiments such as photoconductivity (PC) and Photo Induced Current Transient Spectroscopy (PICTS) show that there is a level at 0.65eV related to Yb. This explains why no Yb3+ photoluminescence (PL) emission is detected, the recombination energy of the trapped excitons is too low (≈ 0.6eV) to excite the Yb3+ internal transition(≈ 1.24eV). We also present results on Er doped GaAs materials. From PL experiments we deduce an estimate of 10−19cm2 for the stimulated emission cross section. By PICTS and PC, we have evidenced a trap at 0.67eV related to Er ions in GaAs. And we think that in this case, the rare earth ions are excited via formation of bound excitons.
Luminescence of TM3+ in Gallium Arsenide Grown by Metal-Organic Vapor Phase Epitaxy
Authors: DÖrnen Achim , Pressel Klaus , Hiller Christoph , Haase Dieter , Weber JÜrgen , Scholz Ferdinand 
Published: March 2011

ABSTRACTWe investigate the excitation mechanism of the characteristic 4f luminescence 3H5 →3H6 of Tm3+ in GaAs by photoluminescence excitation spectroscopy. This luminescence transition is also used to study the incorporation of thulium into the GaAs lattice by angular dependent Zeeman spectroscopy.
Correlation of the Location in Crystal Lattice and Optical Activity of the Yb Impurity in 111-V Compounds
Authors: Kozanecki Adrian 
Published: March 2011

ABSTRACTRutherford backscattering (RBS) and channeling measurements have been applied to study lattice location of the Yb atoms implanted into III-V compounds. It has been found that the Yb atoms locate in the lattice positions only in InP and its alloys with Ga and As, while in gallium compounds the substitutional fraction of Yb atoms could not be detected. The intra- 4f-shell luminescence of the Yb3+ ions in different crystalline matrices have been studied. It has been shown that the ability of efficient excitation of the atomic-like luminescence of Yb3+ ions is associated with their substitutiontl location in the lattice. The intracentre emission from substitutionally located Yb3+ ions may serve as a probe of the local alloy disorder in GaInP and InPAs crystals.
Praseodymium Dioxide Doping of In1−xGaxAsyP1−y Epilayer Grown with Liquid Phase Epitaxy
Authors: Hjelt Kari T. , Sopanen Markku A. , Lipsanen Harri K. , Tuomi Turkka O. , HasenÖhrl Stanislav 
Published: March 2011

ABSTRACTPraseodymium dioxide (PrO2) -doped In0.69Ga0.31As0.67P0.33 layers are grown on semiinsulating In P substrates with liquid-phase epitaxy. The PrO2 doping of the growth solution varies from 0 to 0.32 wt %. The quaternary In0.69Ga0.31As0.67P0.33 layer composition determined with two-crystal X-ray diffraction and photoreflectance is found to be independent of the PrO2 concentration in the melt. The photoluminescence spectra measured at 12 K show both exciton and donor-acceptor peaks, the magnitudes of which depend on the PrO2 doping. The carrier concentration of the n-type quaternary layer decreases and the mobility increases with increasing PrO2 concentration and reaches the values of 8.3.1015 cm−3 and 7300 cm2/Vs, respectively, at about 0.1 wt% at 77 K. The experiments show that PrO2 has an impurity gettering effect in the growth process.
Eu and Yb Excitation Mechanisms in ZnS, CaS, SrS and InP
Authors: Godlewski M. , Światek K. , Monemar B. 
Published: March 2011

ABSTRACTThe role of the excitonic excitation mechanism of the rare earth (RE) intra-shell emission is discussed. Two cases are analyzed. For Yb ion in InP 4f-4f emission of Yb3+ is induced by energy transfer from bound exciton state to the RE core state. For Eu in CaS and SrS RE emission is induced by carrier trapping directly to the excited state of Eu2+ ion. Also in this case the intermediate excitonic state may participate in RE excitation, as suggested by some experimental results.
Electronic Structure of Si Doped by Rare-Earth Yb3+
Authors: Ren Shang Yuan , Dow John D. 
Published: March 2011

ABSTRACTThe electronic structure of Yb3+-doped Si is elucidated in terms of level repulsion between the Si vacancy's deep levels (and spectral density) and the Yb3+ levels, both for bulk Si and for small clusters. The 2F5/2 level of Yb3+ splits into a Γ8 level and a Γ6 level, with the Γ6 repelled most, by the nearby Γ6 (A1) level of the Si vacancy. The level-repulsion is either upwards or downwards in energy, depending on whether the Al-like vacancy level lies below or above this Yb3+ level. The 2F7/2 Yb 3+ level is split into Γ6, Γ7, and Γ8 sub-levels, all moving downwards in energy, with Γ6 moving most, again due to strong level repulsion from the nearby Al-like vacancy level, while the more-distant, higher-energy T2-like (Γ7 and Γ8) vacancy level produces a weaker repulsion. In small clusters, the Si-vacancy's wavefunctions and deep level energies are sensitive to cluster-size, and changes in them alter the level repulsion experienced by the Yb 3+ levels, even though the 4f electrons are localized.
Simple Model for Rare-Earth Impurities in the Compound Semiconductors
Authors: Ilyin Nicolas P. , Masterov Vadim F. 
Published: March 2011

ABSTRACTA model of the ground state for a rare-earth element in a binary semiconductor is suggested and illustrated for ytterbium in InP. It is shown that the charge state of Yb3+ with 4f13 shell is more stable than the state of Yb2+ with f 14 shell.
Growth of Er Doped si Films by Electron Cyclotron Resonance Plasma Enhanced Chemical Vapor Deposition
Authors: Rogers Jim L. , Varhue Walter J. , Adams Edward 
Published: March 2011

ABSTRACTThin Si films doped with Er have been grown at low temperature by plasma enhanced chemical vapor deposition. The Er gas source is a sublimed organo-metallic compound fed into the process chamber. High doping concentrations without precipitation are possible because of the low deposition temperatures. The process relies on the beneficial effects of low energy ion bombardment to reduce the growth temperature. The ions as well as reactive chemical species are produced by an electron cyclotron resonance (ECR) plasma stream source. A hydrogen plasma stream is used to perform an in-situ pre-deposition clean to remove oxide from the Si surface. Film crystallinity and impurity concentration are determined by Rutherford backscattering spectrometry.
Monocrystal Dislocationless Si :Ge, Grown from The Melt With Gd Impurity.
Authors: V.V. Borschensky , D.I. Brinkevich , V.V. Petrov , V.S. Prosolovch 
Published: March 2011

ABSTRACTThe properties of Si grown from the melt having impurities of germanium and gadolinium have been studied by IR-absorption and Hall effect methods.It was stated that Ge and Gd are effective getters for technological impurities of oxygen and carbon in silicon melt. It has been shown that the combined doping by rare earth and isovalent impurities allows to increase the thermostability of dislocationless monocrystals of silicon.
Epitaxial Layers Si:(Sn,Yb) Produced by The Crystallization From The Melt-Solution On The Basis Of Sn.
Authors: Brinkevich D.I. , Kazuchits N.M. , Petrov V.V. 
Published: March 2011

ABSTRACTEpitaxial layers (EL) Si:Sn doped with Yb in the process of liquid phase epitaxy were studied by optical microscopy and photoluminescence (PL) methods.At low concentration of lanthanoid (0,01 < Nyb < 0,1 weight %) the good planarity of the interface and high quality of the surface are detected. At NYb > 0,1 weight % microirregularities are presented.In EL Si:(Sn, Yb) irradiated by 4,5 MeV-electrons the suppression of the generation of radiaton defects, responsible for G- and C-lines of PL, has been found. This effect has been explainedwithin the score of the model takeng into the consideration gettering propering ofYb in reference to the impurities of 0 and 0 as deformation fields, attributed to the presence of Sn atoms.
Microstructure Based Modelling of Stress Migration and Electromigration Induced Failure Distributions
Authors: Børgesen P. , Korhonen K. A. , Brown D. D. , Li C.-Y. 
Published: March 2011

AbstractStress and current induced degradation of the interconnects may well define the ultimate limits on device density and total on-chip power in microelectronic circuits. The two damage mechanisms are found to be mutually interdependent in a fashion determined by the line microstructure, as well as by design features such as W-studs and refractory metal back up layers. We have developed a comprehensive model for the synergistic effects of stress migration and electromigration, taking such factors into account. The present work reviews the modelling of the statistical failure distributions, with emphasis on the temperature and current density dependencies, for the case of ‘near-bamboo’ submicron lines.
Observation and Modelling of Electromigration-Induced Void growth in Al-Based Interconnects
Authors: Kraft O. , Bader S. , Sanchez J.E. , Arzt E. 
Published: March 2011

AbstractAccelerated electromigation tests on unpassivated, pure aluminum interconnects were performed. The failure mechanisms were observed by interrupting the tests and exanming the conductor lines using an SEM. Because the metal thin film was subjected to a so-called laser reflow process before patterning, grain boundaries were visible in the SEM as thermal grooves. Voids were observed to move along the line and to grow in a transgranular manner, and a characteristic asymmetric void shape was identified which seems to be related to the failure mechanism. It is argued that substantial progress in modelling and understanding of electromigration failure can be made by consideration of such void shape effects.
Analysis of Stresses at Singular Points of Patterned Structures
Authors: Chouaf A. , Loppin O. , Ignat M. , Terriez J.M. 
Published: March 2011

AbstractAn iterative method describing the stress state at the vicinity of singularity point is presented here. This approach is based on concepts of rupture mechanics, uses classical solutions from finite element calculations and concerns plane problems. Through this approach, the stress state at the vicinity of several types of singular points in a patterned structure were analysed. The obtained results can be discussed according to failure mecanisms.
X-RAY Determination and Analysis of Residual Stresses in Uniform Films and Patterned Lines of Tungsten
Authors: Maniguet L , Ignat M. , Dupeux M. , Bacmann J.J. , Normandon Ph. 
Published: March 2011

AbstractThe determination by X-ray diffraction of the elastic strain tensors and the corresponding stress tensors in uniform films and patterned lines of tungsten was used to investigate the effect of line width. The stresses were found to increase with increasing line width. These experimental results are discussed with respect to the values obtained from a model using a distributed force in the line. The results of the calculations are in agreement with the X-ray measurements. The edge effects appear to be significant for tungsten lines.
Empirical Modeling of Electromigration Early Resistance Changes
Authors: Niehof J. , de Graaff H.C. , Verwey J.F. 
Published: March 2011

AbstractAn empirical model for electromigration-induced early resistance changes is given. The basis olthe model are two coupled partial differential equations, one for vacancies, and one for mobile atoms. These equations are then solved numerically. For model verification purposes model calculations are compared with experimentally obtained resistance change curves.
Comparison Between I/F Noise, High-Resolution Resistometric, and Lifetime Electromigration Studies of AL and AL(SI)
Authors: Kraayeveld J.R. , Verbruggen A.H. , Radelaar S. 
Published: March 2011

AbstractTo compare the results obtained by 1/f noise, high-resolution resistance and electromigration lifetime measurements, the effect of annealing at 400 °C in forming gas of Al and AI(Si) thin films has been studied. All samples of a given composition have been fabricated simultaneously. Upon annealing, the 1/f noise measured at room temperature decreases by a factor of two whereas the lifetime increases by a factor 3 to 6. The activation energies derived from the 1/f noise and the high-resolution resistance measurements during and after stressing with a DC current are closely correlated and compare well to values reported for lifetime measurements. Comparing the data of the different experiments suggest that the lifetime experiments predominantly probe the presence of weak spots in the films whereas the noise measurements respond more to local disorder.
Theory of Microstructure Evolution in Heterogeneous Materials
Authors: Pantelides Sokrates T. 
Published: March 2011

AbstractThis paper summarizes the main ingredients of a general theory for a quantitative description of dynamical processes in heterogeneous materials under stresses, thermal cycling, or current. The theory is derived analytically from the atomic scale using the principles of quantum mechanics and statistical mechanics, without any empirical postulates. The equations describe the cross-coupled phenomena of stress-induced diffusion, diffusion-induced stress, electromigration, void growth, dislocation climb, and slip. The laws of continuum mechanics are recovered as a subset of the general equations. All constitutive relations can be constructed by a general and systematic procedure.
Theoretical Studies of Electromigration in Polycrystalline Metal Stripes
Authors: Maroudas Dimitris , Pantelides Sokrates T. 
Published: March 2011

AbstractA systematic analysis is presented of the mesoscopic mechanisms that govern the structural evolution of polycrystalline conductors under the action of applied electric fields. A recently derived set of general dynamical mesoscopic equations is specialized to study the behavior of microstructural building blocks. Scaling analysis is presented for the dynamics of the corresponding transport and micromechanical processes associated with a wide range of time scales. Results of numerical simulations are presented for vacancy migration along grain boundaries, evolution of current-induced stresses, surface diffusion, and void stability and growth. The calculated dependence of characteristic times on current density is discussed.
The Microstructural Nature of Electromigration and Mechanical Stress Voids in Integratedcircuit Interconnect
Authors: Rose Jamie H. , Spooner Terry 
Published: March 2011

AbstractIt is well known that stress and electromigration induced voiding is of major concern for integrated circuit interconnect reliability. However, there has been little systematiccharacterization of void morphology and crystallography in ever more technologically important narrow, “near-bamboo” conducting lines. Prior reports indicate thatvoids are typically wedge or slit shaped, with failure often associated with slit voids.Void face habit plane is most often reported to be {111}. Wedge and slit void morphology and crystallography have been studied in comb/serpentine and parallel line array test structures. In virtually all cases, void faces are {111} oriented. In contrast to earlier studies, intragranular wedge stress voids have been observed. All electromigration opens were due to slit voids; these were typically intragranular, in contradiction to current theories of void formation, and likely are mechanical fractures. Under accelerated test conditions, non-grain boundary diffusion paths appear to operate at distances of tens of micrometers. Relative displacement between wedge voids and attached grain boundaries occurs where a wedge face lies on a near common {111} plane for the two grains. It is suggested that slit voids are intragranular under both stress and electromigration conditions and likely associated with local interconnect depassivation. Based solely on appearance and crystallography, no void can uniquely be identified as due to stress alone or electromigration alone.
Characterization of the Degradation Processes in SiO2-Si Structure by Means of Electrolyte-Insulating-Semiconductor Systems
Authors: Bota S.A. , Morante J.R. , Baraban A.P. , Bulavinov V.V. , Konorov P.P. 
Published: March 2011

AbstractA non destructive method to characterize the properties of SiO2 films in SiO2-Si structures and analyze their variations under different external actions is presented and discussed. The method is based on the properties of the Electrolyte-SiO2 contact under polarization which allows us to study the SiO2 film in different injection conditions, in a hole injection zone, in a predominant electron injection zone, and finally, in a region of electron heating as a result of the electric field action before to reach the oxide breakdown. Moreover, using this method, higher electric field values than in the metal-SiO2-Si system can be applied.The characterization of hole traps, electron traps and defect precursors states in SiO2 films are carried out as well as their evolution and influence on the SiO2-Si structure degradation and electrical behaviour. Results measured on SiO2-Si structures obtained from different technological processes and submitted to different treatments are reported in order to discuss the possibilities of this method as a power tool to assess the stability and quality of insulating layer on semiconductors.
Mechanical Stability of Passivation Films Deposited on Aluminium Substrates
Authors: Scafidi P. , Ignat M. , Dupeux M. 
Published: March 2011

AbstractThe damage of films of two different passivation materials deposited on aluminium substrates was investigated. These systems were subjected to uniaxial stretch in an in situ tensile testing device adapted to a scanning electron microscope. Successive stages of crack development were observed: the failure is first in the film, then at the interface. The presence of a thermally grown aluminium oxide interlayer delays the decohesion process. The substrate surface roughness weakens the systems. The evolution of the crack density with the longitudinal strain was analysed and then fitted with a model based on a Weibull distribution function.