bluuebunny/crossref_metadata_2025_split huggingface dataset:
Laser Assisted Chemical Vapor Deposition of Cu from a New Cu Organometallic Complex
Authors: Han Jaesung , Jensen Klavs F. , Norman John A.T. 
Published: March 2011

AbstractWe describe pyrolytic laser assisted chemical vapor deposition (LCVD) of copper onto silicon using a copper(I) hexafluoroacetylacetonate trimethylvinylsilane organometallic complex with 514.5 nm radiation from an Ar+ laser. Growth rates of 0.4-40 μm/min were obtained and at intermediate laser powers, the Cu lines had a resistivity comparable to that of bulk Cu. The line shape and morphology was strongly dependent upon laser power with volcano shapes appearing at higher powers. The growth was sensitive to the nature of the substrate suggesting that film nucleation was a critical element in the writing process.
Coarsening in Two-Dimensional Soap Froths and the Large-Q Potts Model
Authors: Grest Gary S. , Glaziers James A. , Anderson Michael P. , Holm Elizabeth A. , Srolovitz David J. 
Published: March 2011

ABSTRACTA detailed comparison between the experimental evolution of a two-dimensional soap froth and the large Q state Potts model is presented. The pattern evolution starting from identical initial conditions will be compared as well as a variety of distribution functions and correlations of the two systems. Simulations on different lattices show that the discrete lattice of the Potts model causes deviations from universal domain growth by weakening the vertex angle boundary conditions that form the basis of von Neumann's law. We show that the anisotropy inherent in a discrete lattice simulation, which masks the underlying ‘universal’ grain growth, can be overcome by increasing the range of the interaction between spins or increasing the temperature. Excellent overall agreement between the kinetics, topological distributions and domain size distributions between the low lattice anisotropy Potts-model simulations and the soap froth suggests that the Potts model is useful for studying domain growth in a wide variety of physical systems.
Kinetics of Facet Formation During Growth and Etching of Crystals
Authors: Vlachos D. G. , Schmidt L. D. , Aris R. 
Published: March 2011

ABSTRACTMorphological instabilities of surfaces with respect to faceting in deposition of microelectronic materials and etching of semiconductors and catalysts are of great technological importance. Macroscopic theories fail in predicting correctly the time and size dependence of microstructures observed.We have examined the temporal and spatial evolution of unstable interfaces in zero net flux, growth, and etching of crystals as functions of temperature and degree of irreversibility using the Monte Carlo method. In addition to faceting, thermal or kinetic roughening transitions are also observed under some conditions. We have found that the type of transition and the surface structures depend strongly on the irreversibility of the process and the surface temperature. It is demonstrated that surface diffusion has a profound influence on the transitions and surface morphologies.
Structure of Au-Al2O3 Granular Metal Films
Authors: Abeles B. , Zhang Q. , Hung H. H. , Liang K. S. , Ohtani H. , Behal S. K. , Disko M. M. , Lanford W. A. , Gadenne M. , Gadenne P. 
Published: March 2011

ABSTRACTWe have investigated the structural properties of sputter deposited granular AU-Al2O3 films. The films exhibit an abrupt percolation transition from insulating to metallic behavior at the composition of xc-40 vol.% Au. STM measurements yield images of individual grains and clusters of grains consistent with the TEM images. The surface roughness increases abruptly from 30Å to 50Å as the Au concentration increases from 35 to 45 vol.%. The roughening of the films in the metallic regime is consistent with behavior of the X-ray reflectivity.
Epitaxial Growth and Recovery: an Analytic Approach
Authors: Zangwillt A. , Luset C. N. , Vvedensky D. D. , Wilby M. R. 
Published: March 2011

ABSTRACTMost detailed studies of morphological evolution during epitaxial growth and recovery make use of computer-based simulation techniques. In this paper, we discuss an alternative, analytic approach to this problem which takes explicit account of the atomistically random processes of deposition and surface diffusion. Beginning with a master equation representation of the dynamics of a solid-on-solid model of epitaxial growth, we derive a discrete, stochastic equation of motion for the surface profile. This Langevin equation is appropriate for growth studies. In particular, we are able to provide a microscopic justification for a non-linear continuum equation of motion proposed for this problem by others on the basis of heuristic arguments. During recovery, the deposition flux and its associated shot noise are absent. We analyze this process with a completely deterministic equation of motion obtained by performing a statistical average of the original stochastic equation. Results using the latter compare favorably with full Monte Carlo simulations of the original model for the case of the decay of sinusoidally modulated initial surfaces.
The Evolution of Periodic Step Arrays on Si by Surface Diffusion
Authors: Keeffe Mary E. , Umbach C. C. , Blakely Jack M. 
Published: March 2011

AbstractPeriodic step arrays on Si(001) surfaces have been produced using photolithography, reactive ion etching and vacuum annealing. These have been studied by optical diffraction, low energy electron diffraction(LEED), and scanning tunneling microscopy (STM). The periodically varying step density on these arrays has been examined by STM. For small deviations from (100) along the [110] zone, single atomic steps dominate, while at larger angles biatomic steps are the most common; at intermediate angles the steps are of mixed character and there is some evidence for a range of unstable orientations. Interesting differences in the ratio of the areas of the two types of terrace (2×1) reconstructions are observed for the minima and maxima of the quasi- sinusoidal surfaces; these differences may be due to stresses produced by the step arrays or to differences in the line tensions associated with the two different types of steps on reconstructed Si(001) surfaces. The observations will be compared to the predictions of capillarity theory for isotropie materials. At high temperatures surface diffusion leads to a decay in amplitude of these surface gratings probably by mutual annihilation of atomic steps at the extrema. The overall rate of this process has been followed by monitoring the change in the distribution of intensity in the diffraction pattern from the grating using a He-Ne laser while the sample is annealed in UHV. With some simplifying assumptions, the intensity distribution can be directly related to the grating amplitude. The experiments are being performed for a range of grating spacings (to allow identification of the dominant transport process from scaling laws) and for a range of temperatures. The relationship between the ‘macroscopic’ observations of the shape development and the STM results will be explored.
Molecular Dynamics Studies of Impurity Segregation and Trapping.
Authors: Gilmer G. H. , Roland Christopher , Karunasiri R. P. U. 
Published: March 2011

ABSTRACTThe ability to make highly doped δ-layers in semiconductors depends on the rate of interchange of atoms between layers at the crystal surface. We have simulated molecular beam epitaxy on a silicon (100) surface covered with a monolayer of impurity atoms. The kinetics of impurity segregation to the surface was examined for various growth conditions and segregation energies. We find that segregation is facilitated by appreciable inter-layer diffusion of atoms in the top several layers. The amount of diffusion is much greater during deposition than it is when the beam is off.
Cluster Size Distributions in Different Temperature Regimes: The System Ga on GaAs(001)
Authors: Ren Y. , Zinke-Allmang M. , Feldman L. C. , Van Saarloos W. 
Published: March 2011

ABSTRACTIn this paper we discuss results for the clustering of Ga on GaAs(001). The dominant dynamic process which drives this system toward this three dimensional equilibrium changes from Ostwald ripening at low deposition rates to coalescence at higher deposition rates. The experimental data allow us to test several theoretical predictions for cluster size distributions based on a detailed study of the microscopic processes. These include, at higher deposition rates, the observation of local ripening effects and diffusion limited growth.
Molecular Dynamics Simulation of A Langmuir Monolayer
Authors: Bareman James P. , Klein Michael L. 
Published: March 2011

AbstractMolecular dynamics calculations were carried out for a Langmuir monolayer at high density. A model was employed in which the motions of both the amphiphiles and the water are allowed, enabling investigation of the details of the water-monolayer interaction and the structure of the interface. Results are presented for the density profiles of the water and the amphiphiles and for the distribution ofgauchedefects.
The Many Facets of Interface Motion.
Authors: Cahn John W. 
Published: March 2011

ABSTRACTMany dynamic growth processes are shown to involve changes in more than one of the nine geometric variable that describe the geometry of a planar interface between crystals. Even simple examples illustrating changes in each one of the nine are found to involve some of the others. A generalized concept of crystal-crystal interface motion, using all nine variables, is suggested.
Monte Carlo Simulations of Growth Kinetics and Phase Transitions at Interfaces: Some Recent Results
Authors: Nielaba P. , Binder K. 
Published: March 2011

ABSTRACTIn the first part Monte Carlo studies of the kinetics of multilayer adsorption (without screening) are described. The approach to the jamming coverage in each layer is asymptotically exponential. The jamming coverages approach the infinite-layer limit value according to a power law. In the second part, studies of phase transitions in two dimensional fluids are reviewed. With a combination of Monte Carlo and finite size scaling block analysis techniques, accurate values are obtained for the critical temperatures, coexistence densities and the compressibilities of an adsorbed fluid layer in an NVT ensemble.
Facet Formation on Single Crystal TiO2 Surfaces Studied by Atomic Force Microscopy
Authors: Antonik M. D. , Edwards J. C. , Lad R. J. 
Published: March 2011

ABSTRACTAtomic force microscopy (AFM) and low energy electron diffraction (LEED) have been used to study the faceting behavior on (001) and (100) surfaces of a TiO2 single crystal. On the TiO2 (001) surface, LEED patterns characteristic of {011} facet planes develop after annealing below 900 °C in agreement with previous studies, but AFM shows a complex surface morphology consisting of a large distribution of facet sizes and orientations. After annealing at 1300 °C, facets do not form but rather a network of 5 – 30 nm high ridges develops over the entire surface. These ridges may be the result of surface defects produced by changes in bulk stoichiometry during annealing. On the TiO2 (100) surface, facets are also observed after annealing below 900 °C. However, these facets have extremely small height to width aspect ratios and are not discernible with LEED.
Molecular Beam Epitaxial Growth of (Al,Ga)As Tilted Superlattices on Vicinal GaAs (110)
Authors: Krishnamurthy Mohan , Wassermeier M. , Weman H. , Merz J. L. , Petroffa P. M. 
Published: March 2011

ABSTRACTA study of the molecular beam epitaxial (MBE) growth on singular and vicinal (110) surfaces of GaAs is presented. Quantum well structures and tilted superlattices (TSL) were grown on substrates misoriented 0.5°-2° towards the nearest [010] and [111]A azimuths at growth temperatures ranging from 450° C to 600° C under different growth conditions. The structures were characterized by Nomarski optical microscopy, transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy.Two types of faceting were observed on the surfaces. The structures grown at temperatures above 540°C and As beam fluxes below l×10-5 torr showed V-shaped facets pointing in the [001] direction and are attributed to As deficient island growth. Lower temperatures and higher As beam fluxes lead to surfaces with microfacets that are elongated along the respective step directions on the vicinal surface and are due to step bunching during growth. Their density and height decrease with decreasing vicinal angle and they disappear on the singular (110) surface. The photoluminescence of the GaAs quantum wells grown on these samples is redshifted with respect to that of the quantum wells grown on the flat surface. This is being ascribed to the fact that on the vicinal surface, the recombination takes place at the facets where the quantum wells are wider.The contrast in the TEM images of the TSL show for the samples misoriented towards [010] that the lateral segregation to the step edges on this surface is appreciable. The TSL spacing and the tilt however show that during growth the vicinal surfaces tend towards a surface with smaller miscut.
Radio Frequency Power Dependence of Defect Density at Hydrogenated Amorphous Silicon Interface
Authors: Ihara Hisanori , Sakakubo Takeo , Nozaki Hidetoshi 
Published: March 2011

ABSTRACTA hydrogenated amorphous silicon (a-Si:H) interface fabrication technology for the plasma CVD method, which can produce low interface defect density, is presented. The relation between the interface defect density and radio frequency (RF) power was investigated. As a result, the difference between the interface defect density and the bulk defect density decreased with increasing the RF power. A high RF power (25 W) a-Si:H buffer layer 5 nm thick was deposited on the interface before depositing low RF power (5 W) a-Si:H layer with a low bulk defect density. It has been found that the ideal defect density distribution, which shows the uniform distribution with the very low defect density (4.2×1014 cm) from the i/i interface to the bulk, can be accomplished by 5 nm buffer layer.
In-Situ Studies of the Formation Sequence of Silicides During Vacuum (10-7 TORR)Thermal Annealing of TI/Polysilicon Bilayers
Authors: Ma Z. , Allen L. H. , Lee S. 
Published: March 2011

ABSTRACTThe formation of suicides during the thermal reaction of Ti/polysilicon bilayers has been investigated using both in-stu four point sheet resistance measurements and ex-situ measurements including X-ray diffraction, cross-sectional transmission electron microscopy and Auger electron spectroscopy. For a series of samples annealed at a ramp rate of 10°C/min the following sequence of changes in the bilayers occurred. At temperatures exceeding 350°C and prior to the silicidation oxygen from the vacuum system diffuses into the Ti film forming a solid solution of Ti(O) with O levels up to 20 %. An amorphous TixSiy layer is the first major suicide reaction observed at temperatures near 440°C. The first major crystalline phase is observed at 500°C and identified as C49 TiSi2. This phase was found to coexist at these temperatures with the partially consumed Ti(O) and the amorphous TixSiy layers. Further annealing above 700 °C results in the final structural transformation from C49 TiSi2 to C54 TiSi2.
Structures and Properties of Quasi-Multilayered Nanocomposites
Authors: Motohiro T. , Watanabe Y. , Takeda Y. , Noda S. , Toklzakl T. , Nakamura A. 
Published: March 2011

ABSTRACTVertical sections of multilayers (VSM) should provide excellent testing grounds for physics and chemistry on surfaces with densely populated heterogeneous interfaces. Although VSM can be obtained from usual horizontal multilayers stacks by crushing them into pieces or by partial ion etching through masks from the top surfaces, a better way to get VSM is to form vertical multilayers. Employing simultaneous oblique deposition of ZnTe and SiO2 from opposite azimuthal directions, we have obtained nanometer-scale heterogeneous structures with anisotropie optical properties for the light coming perpendicularly to the surface. TEM revealed that successive annealing caused relaxation and recrystalllzation of ZnTe in the framework of SiO2 porous nano-structure. The resultant mosaic image of dark ZnTe regions and bright Sio2 regions of 5–10 nm wide and 30nm (or more) long told the development of VSM over the substrate although the perfect periodicity and two-dimensionality were missing. The structural modification of these quasi-multilayers was studied making reference to the similar but horizontal system of ZnTe particles periodically buried between Sio2 isolation layers.
Interface Stabilization of W-N Coatings by Chromium Alloying
Authors: Knotek O. , Löftier F. , Barimani A. 
Published: March 2011

ABSTRACTNew metastable materials can be deposited using low temperature physical vapour deposition (PVD) techniques. During reactive sputtering, the atoms condensing in an intermixed state attempt to achieve a stable configuration. Due to low mobility of the adatoms, equilibrium phases cannot form and metastable structures are observed. Reactive sputtering can be used to deposit films with different stoichiometries and structures in the W-N system. The metastable phases α-W. β-W. W2N and WN1−x are obtained. All coatings are, however, thermally unstable. At temperatures above 570 °C. all phases are transformed into the a-W modification. By alloying chromium to the coatings in the W-N system, it is possible to stabilize all tungsten and tungsten nitride modifications as well as the interface layer between the substrate and the thin films.
Wetting of a Smooth Substrate by Crystal
Authors: Courtemanche David J. , van Swol Frank 
Published: March 2011

AbstractWe report on a molecular dynamics (MD) study of the wetting state of a system of hard spheres near a smooth planar hard wall. A direct simulation at the melting point of a two-phase system between two walls develops all the way from complete wetting by fluid (cos(θ) = 0) via partial wetting state to a final arrangement of complete wetting by crystal (cos(θ) = 1). This implies that a hard sphere fluid spontaneously crystallizes at a smooth hard wall, contrary to existing beliefs.
Characterization of P+-Implanted Silicon
Authors: David Theodore N. , Knoch Lynnita , Christiansen Jim , Pan M. 
Published: March 2011

ABSTRACTDopant species can interact in different ways with interfaces, layers of varied microstructures, and with extended-defects. An understanding of such interactions is relevant to semiconductor processing and device-fabrication. In this study, the behavior of phosphorus-implanted silicon wafers was characterized using transmission electron microscopy (TEM), for as-implanted as well as post-implant rapid thermal-anneal (RTA) conditions. The top layers of as-implanted wafers were found to be amorphized. A correlation was seen between the presence of the amorphous-to-crystalline silicon interface and a drop in phosphorus concentrations in depth-profiles obtained using SIMS (secondary-ion mass-spectrometry). Reasons for the drop in concentration are explored, one of which is a higher diffusivity for phosphorus in amorphous silicon than in crystalline silicon. The top layers of wafers subjected to a RTA had recrystallized. A band of extended defects was present in the vicinity of the original amorphous-to-crystalline silicon interface. A correlation was seen between the presence of these defects and a secondary peak in phosphorus concentrations (in depth profiles) obtained using SIMS. These effects are explained in terms of gettering of phosphorus to the extended-defects. The band of extended-defects consists of dislocation loops, point-defect clusters, and extended dislocations that arise due to coalescing of point defects followed by annealing of the resulting extended-defects. The point-defects themselves arise from the implantation.
Principles and Performance of a PC-Based Program for Simulation of Grazing Incidence X-Ray Reflectivity Profiles
Authors: Wormington M. , Bowen D. K. , Tanner B. K. 
Published: March 2011

ABSTRACTWe describe PC- based software which calculates grazing incidence X-ray reflectivity profiles from model thin film structures, including interface grading. We discuss the mathematical principles of the model and benchmark tests for speed of operation on two PC compatible machines are presented. Curvature of the specimen results in selective loss of fringe visibility at low scattering vectors and is treated rigorously. We discuss the treatment of roughness and use a generalized formula that is valid at large and small values of the reflectivity; its effects are illustrated using the program.
Tilts in Thin Strained Layers.
Authors: Beanland Richard 
Published: March 2011

ABSTRACTThere is considerable interest at present in the mechanisms of tilting of epitaxial films, such that low index planes in layer and substrate have slightly different orientations. There are two primary causes of this effect: a) coherency strains and b) the action of misfit dislocations. It is important to distinguish between the two effects, particularly in the case of strained layers used for band-gap engineering. Using a recent formulation of the Frank-Bilby equation for the dislocation content of interfaces, it is shown how planes may be rotated in coherent layers due to both the Poisson effect and anisotropic misfit. An advantage of the Frank-Bilby equation is that it allows consideration of semicoherent layers. It is shown that a side effect of misfit dislocation introduction can be to introduce a further rotation of the epitaxial layer. Both these effects have been measured experimentally. The amount and the sense of rotation is compared to theory.
The Influence of Grain Boundary Inclination on the Structure and Energy of Σ3 Twin Boundaries in Copper
Authors: Wolf Ulrich , Ernst F. , Muschik T. , Finnis M. W. , Fischmeister H. F. 
Published: March 2011

ABSTRACTIn a combined theoretical and experimental study, the energies and structures of Σ3 [011] twin boundaries in Cu were investigated. The atomic structures and the grain boundary energies were calculated using the Embedded Atom Method (EAM). Grain boundary energies of welded Cu bicrystals of the same boundary orientations were also obtained by the thermal grooving technique. The atomic structure of the symmetric {211} incoherent twin boundary (SITB) was investigated by High Resolution Transmission Electron Microscopy (HRTEM). Calculated grain boundary energies γb plotted against the inclination angle Φ of the boundary plane relative to the {111} coherent twin boundary (CTB) plane show a mininmm for the CTB (Φ = 0°) and a second minimum at Φ = 82°. This dependence on the inclination is also confirmed by the measured energies. Common to all calculated boundary structures is a microface 11 ing into CTB and SITB segments with a symmetric orientation of the adjacent crystals. Additionally, strong relaxations occur for the grain boundaries near the second energy minimum. This relaxation can be interpreted as a sequence of stacking faults located almost perpendicular to the mean boundary plane. They are terminated by partial dislocations which form a small angle boundary. The most apparent feature of these structures is a bending of the {111} planes running across the boundary. The structural properties were confirmed by HRTEM.
Reactions at Solid Interfaces
Authors: Sinclair R. , Ko D. H. , Konno T. J. , Nolan T. P. 
Published: March 2011

ABSTRACTThis article discusses some of the changes which can occur at interfaces due to reaction or annealing. For chemically unstable interfaces, the atomic recombinations result in formation of new phases, which can even be amorphous in the initial stages. When no further chemical evolution takes place, physical rearrangement can have important consequences on the structure and properties. Examples are drawn from work on Ti-Si, Pt-GaAs, Ti-Si-O-N, Al-Si and TiSi2-Si.