bluuebunny/crossref_metadata_2025_split huggingface dataset:
CoSi and CoSi2 Phase Formation on Bulk and Soi Si Substrates
Authors: Hsia S. L. , Tan T. Y. , Smith P. L. , Mcguire G. E. 
Published: September 2012

ABSTRACTWe have studied the CoSi and CoSi2 phase formation sequence in (001) bulk and SOI Si wafers, using Co/Ti bimetallic layers as source materials which are suitable for growing epitaxial CoSi2 films on (001) Si. In bulk Si, co-formation of polycrystalline CoSi and epitaxial CoSi2 phases at T>500°C have been observed. These phases form respectively at the metal and Si sides of the film. For very long times and/or at high temperatures, only epitaxial CoSi2 is observed, e.g., for samples annealed at 560°C for 30 min or at 900°C for 10 s. When using (001) SOI Si with inexhaustible Co supply, only polycrystalline CoSi has been formed for a 900°C 10 s annealing, which is in contrast to the bulk Si results. This phenomenon is understood on the basis of Gibbs free energy reduction in forming the two phases. In the CoSi2 formation temperature range, Gibbs free energy release in forming CoSi2 is only ∼10% more than that of forming CoSi. Consequently, after all Si atoms have been consumed, the formation of CoSi becomes energetically more favorable, since the free energy reduction due to formation of 2x mole of CoSi is much larger than that due to formation of lx mole of CoSi2, where x is the SOI Si mole number.
Silicidation Mechanism of Co/(Refractory-Metal) Bilayer and Epitaxial Growth of CoSi2 on Si(100) Substrate
Authors: Byun Jeong S. , Kim Woo S. , Choi Min S. , Cho Ho J. , Klm Hyeong J. 
Published: September 2012

ABSTRACTThe structures of CoSi2 formed from the bilayer of Co/(refractory metal) have been investigated. For a layer reversal and epitaxial growth of CoSi2 on Si substrate, the silicidation temperature of interposed refractory metal should be higher than that of Co and the oxidation potential of the refractory should also be negatively higher than that of Si to remove the native oxide on Si substrate. The main role of the refractory metal layer in the epitaxial growth of CoSi2 is to limit the Co diffusion to Si substrate, controlling the Co-Si reaction rate. Thus Co atoms are able to locate their stable positions with the lowest energy in CoSi2 lattice.
Microstructure Analysis of Agglomerated Epitaxial Columns of Si/PtSi/Si(111) Double Heterostructure
Authors: Park Kyung-Ho , Kumagai Y. , Hasegawa F. 
Published: September 2012

ABSTRACTMicro structures and interface structures of epitaxially grown PtSi and over-capping Si films on Si(111) substrates prepared by MBE were studied by RHEED, HREM, SEM and XRD. An epitaxially grown Si layer on the PtSi layer, which was fabricated by coevaporation of Pt and Si with the stoichiometric ratio (Pt/Si=l/1), was obtained as a Si(111)/PtSi(010)/Si(111) double heterostructure at the substrate temperature of 400°C. On the other hand, it was found that the PtSi layer transformed into epitaxial columns and/or walls when a Si over-capping layer was grown on the PtSi layer at a substrate temperature of 600°C or higher. These columns and/or walls were surrounded by a Si matrix which showed epitaxial relations to the Si substrate with stacking faults.
Arsenic Diffusion and Segregation Behavior at the Interface of Epitaxial CoSi2 Film and Si Substrate
Authors: Hsia S. L. , Tan T. Y. , Smith P. L. , Mcguire G. E. 
Published: September 2012

ABSTRACTArsenic diffusion and segregation properties at the interface of the epitaxial CoSi2 and Si substrate have been studied. Samples have been prepared using Co-Ti bimetallic source materials and two types of (001) Si substrates: n+ (doped by As to ∼2}1019 cm−3) and p. For the n+ Si cases, the lower limit of the CoSi2 film formation temperature is increased by ∼200°C to ∼700°C. SIMS results showed As segregation into Si. For epitaxial CoSi2 film formation at 900°C, the As concentration has increased by a factor of ∼2 within a distance of ∼30nm from the interface, while the incorporated As in the film is ∼30-50 times less than that in Si. For p-type Si substrate cases, the epitaxial CoSi2 film was first grown and followed by As+ implantation (into the film) and drive-in processes. It is observed that As was segregated to the CoSi2-Si interface and diffused into Si. This is in qualitative agreement with our results obtained from the n+ substrate experiments and the results of other authors involving the use of polycrystalline CoSi2 films. In the present cases, all implanted As were conserved at a drive in-temperature of 1000°C for up to 100 s. This is in contrast to the polycrystalline CoSi2 film results which involve a substantial As loss to the film free surfaces. The physical reasons of this difference have been discussed.
Kinetics of Ni Silicides Synthesis with Excimer Laser Pulses Studied by TRR
Authors: Černý R. , PŘkryl P. , El-Kader K.M.A. , Engst P. , KubÁt P. , ChÁb V. 
Published: September 2012

ABSTRACTTime resolved reflectivity curves (TRR) in combination with non-equilibrium thermal model are used to estimate the temperature interval of chemical reactions in the systems Ni-Si (100) and Ni-SiO2-Si (100) for a ∼ 500 nm thick Ni layer depending on the pulse energy density ranging from 0.5 J/cm 2 to 1.0 J/cm2. Numerical simulations are performed to calculate the temperature field within the system and to analyze the reactivity of the system.
Application of Novel Epitaxy Techniques to the Growth of CrSi2
Authors: Fathauer R.W. , George T. , Jones E.W. , Pike W.T. , Short K.T. , Vasquez R.P. , White Alice E. , Wilkens B.J. 
Published: September 2012

ABSTRACTCrSi2 is of technological interest because it is a silicon-based semiconductor with a small band gap. Due to the lack of success with conventional molecular beam epitaxy of CrSi2 on Si, growth on mesotaxy-produced template layers and allotaxy have been attempted. After removal of the Si capping layer, epitaxy of additional CrSi2 on template layers formed by mesotaxy was found to be possible. However, single-crystal continuous films were not obtained, due at least in part to the presence of a network of cracks in the starting template. Allotaxy of CrSi2 was found to allow the formation of large grains of CrSi2 embedded in a single-crystal Si matrix, but coalescence of these grains into a continuous layer was not achieved.
Optical Properties of Semiconducting Silicides
Authors: Lange H. , Henrion W. , Jahne E. , Giehler M. , GÜnther O. , Schumann J. 
Published: September 2012

ABSTRACTThe optical properties of polycrystalline layers of CrSi2, MnSi1.73, β-FeSi2, and Ir3Si5 prepared by single layer and codeposition methods on different substrates are measured over the spectral range from the infrared to 24 eV. The spectral features in the interband region are attributed to transitions between Si p-metal d bonding and antibonding states mediated by energy dependent matrix elements. The IR spectra of CrSi2 and β-FeSi2, exhibiting six phonon modes, are simulated by an oscillator model.
Point-Contact-Spectroscopy of VSi2, Nbsi2 and Tasi2
Authors: Gottlieb U. , Balkashin O.P. , Jansen A.G.M. , Laborde O. , Madar R. 
Published: September 2012

ABSTRACTWe present point-contact-spectroscopy measurements on VSi2, NbSi2 and TaSi2 high quality single crystals. These three compounds crystallise in the same hexagonal structure (structure C40, space group P6222) and they are isoelectronic. Phonon spectra deduced by this technique are in good agreement with phonon parameters previously obtained from resistivity and low temperature specific heat measured on the same samples.
A Titanium Salicide Process Suitable for Submicron CMOS Applications
Authors: Blair C. , Demirlioglu E. , Yoon E. , Pierce J. 
Published: September 2012

ABSTRACTThis paper reports a titanium salicide process capable of fabricating low resistance salicide (<5 ohms/sq.) on narrow polysilicon leads (line widths less than 0.35 μm) which are heavily doped with arsenic and boron. The process utilizes conventional processing but avoids excessive vertical scaling of the titanium silicide film. The process has been demonstrated on a 0.35 μm CMOS technology and results show that a process window exists which is suitable for technologies of 0.35 μm and below. The most serious scaling issue for titanium salicide appears to be the silicide film thickness.
Electrical Characterisation of Epitaxial (100) CoSi2/Si Contacts Obtained Using a Ti/Co Bilayer
Authors: Lauwers A. , Vercaemst A. , Van Hove M. , Larsen K. Kyllesbech , Verbeeck R. , Van Meirhaeghe R. , Maex K. , Van Rossum M. 
Published: September 2012

ABSTRACTIn this paper the electrical properties of epitaxial CoSi2 on Si obtained by solid-state reaction of a Ti/Co bimetallic layer are investigated. Low temperature resistivity, magnetoresistance and Hall data are presented. The CoSi2ISi Schottky diodes are characterised by current - voltage and capacitance - voltage measurements at temperatures varying between - 100°C and 60°C.
Epitaxial Semiconducting and Metallic Iron Silicides
Authors: Von KÄNel H. , Kafader U. , Sutter P. , Onda N. , Sirringhaus H. , MÜller E. , Kroll U. , Schwarz C. , Goncalves—conto S. 
Published: September 2012

ABSTRACTWe discuss the properties of semiconducting iron silicides, grown epitaxially on Si(001) and Si(111) by molecular beam epitaxy. The growth on Si (111) involves phase transitions from epitaxially stabilized metallic phases, leading to larger epitaxial β-FeSi2 grains than most other deposition procedures. The structural and electric properties of β-FeSi2/Si(001) are improved considerably for growth temperatures above 650 °C. Hall mobilities of p—conducting films reach values up to 600 cm2/Vsec at 100 K, at carrier densities below 1017 cm−3. Despite of the high majority carrier mobility and low carrier density, the photoelectric response of p-β-FeSi2/n-Si(001) diodes does not yield any significant contribution from the silicide, however, in accordance with the expected band structure diagram.
Nature of Environmentally Assisted Fractures in Polycrystals
Authors: GoluboviĆ Leonardo , Peredera Anatoli 
Published: September 2012

AbstractEnvironmentally assisted fracture is in practice one of the most important fracture modes. It is especially dramatic in polycrystalline super-alloys, which are believed to be embrittled by oxygen diffusing along their grain boundaries. We used a large scale atomistic Monte-Carlo simulation to study phenomena of the environmentally assisted fracture nucleation in solids with grain boundaries exposed to an oxygen atmosphere. We find nucleation of inter-granular microcavities in a region which is well in front of the oxidized zone of the sample, apparently due to inhomogeneous stresses induced by the presence of oxide particles. This effect increases with decreasing oxidation rate since then the oxidation front becomes fuzzier and inhomogeneous stresses stronger. These findings compare well with the experimental data on super-alloys which indicate that the environmental embrittlement effects are strong for slower oxidation rates, whereas at higher oxidation rates the embrittlement may be suppressed.
Computer Simulation of Bending Plastic Deformation and Creation of Dislocations in Copper Thin Films
Authors: Tsukahara H. , Niwa Y. , Takayama T. , Doyama Masao 
Published: September 2012

AbstractA small single crystal of copper with a notch has been bent by use of the molecular dynamics method. The bend axis was [110]. Dislocations were created near the tip of the notch and moved on (111) slip plane. Pulling a copper single crystal, half dislocations were created in such a way that the bending was compensated.
Dendritic Growth in Terrestrial and Microgravity Conditions
Authors: Glicksman M.E. , Koss M.B. , Bushnell L.T. , Lacombe J.C. , Winsa E.A. 
Published: September 2012

AbstractDendritic growth is the most ubiquitous form of crystal growth encountered when metals and alloys solidify under low thermal gradients. The growth of thermal dendrites in pure melts is generally acknowledged to be controlled by the diffusive transport of latent heat from the moving crystal-melt interface into its supercooled melt. However, this formulation is incomplete, and the physics of an additional selection rule, coupled to the transport solution, is necessary to predict uniquely the dendrite tip velocity and radius of curvature as a function of the supercooling. Unfortunately, experimental confirmation or evidence is ambiguous, because dendritic growth can be severely complicated by buoyancy induced convection. Recent experiments performed in the microgravity environment of the space shuttle Columbia (STS-62) quantitatively show that convection alters tip velocities and radii of curvature of succinonitrile (SCN) dendrites. In addition, these data can be used to evaluate how well the Ivantsov diffusion solution, coupled to a scaling constant, matches the dendritic growth data under microgravity conditions.
Rupture of Random Fuse Networks: Ductile to Brittle Crossover
Authors: Angulo Rafael F. , Medina Ernesto 
Published: September 2012

AbstractWe study the rupture process of Random Fuse Networks (RFN's) with quenched disorder in the microscopic threshold voltages. If lattices are driven to breakdown in one blow by an externally applied voltage the RFN's are shown to be equivalent to the toughest percolation backbone. Critical path analysis holds exactly in this case for all disorder distributions. For gradual rupture, it is shown that the existence of a lower cutoff in the disorder distributions entails a crossover from ductile to brittle behavior. The crossover length is a function of microscopic disorder and diverges in the limit of infinite disorder.
Fracture Characteristics of Iron-Copper Sintered Compacts
Authors: Tabeshfar Kamran 
Published: September 2012

AbstractA study of fatigue cracking in iron-copper compacts was carried out to compare and analyse the performance of four different types of commercially used iron powders. The compacts were all sintered at above the iron copper peritectic temperature to facilitate liquid phase sintering. Results showed that the powder with a high specific surface had inferior fatigue properties, especially at high stress levels. The other powders, however, had very similar fatigue properties, except that at low stresses the grade with the large average particle diameter resulted in significantly longer fatigue lives. The differences in performance were discussed in terms of the microstructure of the compacts and the powder characteristics.
Dynamic Scaling in Electrochemical Deposition
Authors: Iwasaki Hiroshi , Iwamoto Atsushi , Sudoh Koichi , Yoshinobu Tatsuo 
Published: September 2012

AbstractStatic and dynamic scaling behavior in copper electrochemical deposition in the stable growth condition (non-bulk fractal growth) was studied by atomic force microscopy and numerical simulation. We found two distinct scaling regimes with roughness exponent α of 0.6 and 0.87α0.05 corresponding to the concentrations of the “brightener” organic additive higher and lower than 1 mℓ/ℓ, respectively. The rms surface width of the whole measured area of the surfaces in the former regime was smaller than that in the latter regime. For the latter rougher surface, we observed dynamic scaling behavior for longer length scales as well as the stationary scaling behavior for shorter length scales: surface width did not further increase with linear size of the area for longer length scales than a characteristic correlation length and increased as a power of deposition time with the dynamic exponent β of 0.45. The sum of α + (α/β) was larger than the value expected for KPZ local growth, 2. This was understood that in electrochemical deposition there is enhancement of growth at protrusions owing to non-local Laplacian field effect. The smoother (α =0.6) and the rougher (0.87) surfaces were reproduced by numerical solutions of KPZ + (the growth term proportional to height) for the shorter and the longer growth times, respectively. Bifurcation of the surface morphology is understood as a result of decrease of weight of the additional term owing to increase of the additive.
Pulsed Electrodeposition of Tree-Like Copper Aggregates
Authors: HuttEl Y. , Chassaing E. , Rosso M. , Sapoval B. 
Published: September 2012

AbstractUsing pulsating current technique, we have been able to grow self-sustained, tree-like copper aggregates with a length of a few mm. The size of these aggregates allowed us to perform impedance and scanning electron microscope analysis. The morphology of the aggregates is found to be more compact than for deposits obtained in fixed-current dc conditions. However, their structure is still very irregular, and depends on the parameters characterizing the pulse sequence.
Fractal Structure of A Porous Cross-Linked Polymer Resin and Dynamical Behavior of Adsorbed Solvents
Authors: Korb J.-P. , Chachaty C. 
Published: September 2012

AbstractThe fractal distribution of pore sizes in a poly-4-vinylpyridine resin cross-linked by diamagnetic (Cd2+) or paramagnetic (VO2+, Cu2+) divalent metallic ions has been characterized by small-angle-X-ray scattering, nuclear paramagnetic relaxation and proton-pulsed-field gradient. These complementary techniques show a continuity in the fractal distribution of pore sizes through the same surface fractal dimension, Df = 2.6, over four orders of magnitude between 3 nm to 50 μm. Electron spin resonance yields a direct estimate of the overall fraction of solvent into the adsorption shell of the cross-linked polymer network as well as the dynamics and local viscosity of the solvent in this disordered material.
Diffusion-Limited Aggregation as Branched Growth
Authors: Halsey Thomas C. 
Published: September 2012

AbstractI present a first-principles theory of diffusion-limited aggregation in two dimensions. A renormalized mean-field approximation gives the form of the unstable manifold for branch competition, following the method of Halsey and Leibig [Phys. Rev. A 46, 7793 (1992)]. This leads to a result for the cluster dimensionality, D ≍ 1.66, which is close to numerically obtained values. Quenched and annealed multifractal dimensions can also be computed in this theory; the multifractal dimension τ(3) = D, in agreement with a proposed “electro- static” scaling law.
New Scaling for AC Properties of Percolating Composite Materials
Authors: Brouers F. , Sarychev A.K. 
Published: September 2012

AbstractIn real conductor-insulator composites one observes a sharp change of the dc resistivity and a large increase of the low frequency dielectric constant at the percolation threshold Pc. However in many cases the a.c. data do not follow the scaling behaviour predicted by the percolation theory. To account for these discrepancies, we have proposed an alternative model which incorporates quantum tunnelling into the percolation theory. This models leads to a new “tunnelling” scaling law for the complex conductivity which gives rise for concentration below Pc to an exponential variation of the d.c. conductivity with concentration and a dispersion of the ac complex conductivity with non universal exponents. This new scaling law depends on two new exponents and reduces to the usual one for metal concentration well above Pc:. We apply this more general scaling to discuss the relation between the film morphology and the low frequency dispersion in granular metallic composites.
Scalar Transport by Diffusion and Random Advection
Authors: Araujo Mariela 
Published: September 2012

AbstractThe transport of a scalar by jump-type random advection and diffusion is described by a mean field formulation in terms of a Langevin equation for the fluctuations of the scalar. It is shown how the distribution of the scalar fluctuations is sensistive to the relative strength of advection versus diffusion, and the details of the advection process.
Damping and Spatial Distribution of Percolation Fractons
Authors: Russ S. , Sapoval B. 
Published: September 2012

AbstractThe damping of the vibrations of very irregular discretized systems embedded in a viscous fluid is studied in the particular case of the vibrations of percolation clusters. We develop a formal description for the “regularity” of a vibrational mode. This permits us to measure numerically how the local fluctuations in the vibration amplitude contribute to the viscous damping. The fact that the regularity is found to be larger than that of a single localized state on a linear chain is indicative of the very structure of the percolation cluster made of blobs and red bonds.
Fem Based Simulation of Percolation Features of Disordered Heterogeneous Media Elastic Properties
Authors: Timan S.A. , Oshmian V.G. 
Published: September 2012

AbstractThe mechanical properties of the 2D elastic rigid-nonrigid disordered system in dependence on the concentrations of the rigid phase are studied. The system is constructed on the basis of the square lattice and finite element method (FEM) approximation. The elasticity threshold of the FE system and the critical exponents are detemined by the phenomenological renormalization (PR) of the Monte Carlo data.
Scaling of Transport Properties of Reservoir Material at Low Saturations of a Wetting Phase
Authors: Araujo Y. Carolina , Toledo Pedro G. , Gonzalez Hada Y. 
Published: September 2012

AbstractTransport properties of natural porous media have been observed to obey scaling laws in the wetting phase saturation. Previous work relates power-law behavior at low wetting phase saturations, i.e., at high capillary pressures, to the thin-film physics of the wetting phase and the fractal character of the pore space of porous media. Here, we present recent combined porousplate capillary pressure and electrical conductivity data of Berea sandstone at low saturations that lend support to the scaling laws. Power law is interpreted in terms of the exponent m in the relation of surface forces and film thickness and the fractal dimension D of the interface between pore space and solid matrix. Simple determination of D from capillary pressure and m from electrical conductivity data can be used to rapidly determine wetting phase relative permeability and capillary dispersion coefficient at low wetting phase saturations.
Film Growth: Control of Surface Morphology from Monodisperse Nanoparticles Through Fractals to Flat Epitaxial Heterostructures
Authors: Williams R. Stanley , Tong William M. , Ngo Tue T. 
Published: September 2012

AbstractThe study of the morphology of surfaces produced by vapor deposition began over 125 years ago with Lord Kelvin. Since then, many researchers have addressed this topic from very different theoretical viewpoints, including thermodynamics, kinetics, fractal geometry, and numerical simulations. Only recently, however, have scanning probe microscopes become available to measure the three dimensional topography of a deposited film, which provided the quantitative experimental data necessary to test the different models of film growth. The concept of scaling provides a good first description of the morphology of vapor deposited films of all types, but for heteroepitaxial films, scaling is only approximately valid. The competition between the surface roughening caused by island nucleation and growth versus the smoothening actions of surface diffusion and desorption can lead to the formation of correlated structures on a surface with a dominant spatial frequency. By rational control of the film growth conditions, one can produce a surface covered by a low density of nearly monodisperse nanoparticles, an essentially fractal surface, or a planar film surface.
Roughening by Ion Bombardment: A Stochastic Continuum Equation
Authors: Cuerno R. , Barabasi A.-L. 
Published: September 2012

AbstractIn the context of linear cascade theory, we derive a stochastic nonlinear equation to describe the evolution and scaling properties of surfaces eroded by ion bombardment. The coefficients appearing in the equation are calculated explicitly in terms of the physical parameters characterizing the sputtering process. We find that transitions may take place between various scaling behaviors when experimental parameters such as the angle of incidence of the incoming ions or their average penetration depth, are varied.