bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of the Electron Beam-Induced Shrinkage Rates Of Isolated Amorphous Zones In Germanium
Authors: Jenčič I. , Robertson I. M. , Skvarč J. 
Published: April 2011

AbstractEpitaxial regrowth of isolated amorphous zones, created in Ge by implantation with 50 keV Xe+ ions, was stimulated at room temperature by using electron beams with an energy below that required to create Frenkel pairs. The process was studied by using transmission electron microscopy combined with an automatic computer image analysis program, and the regrowth was characterized by determining the shrinkage rate of the effective radius of individual zones. The effective radius decreases approximately linearly with electron dose. The regrowth rate of irregular shaped amorphous zones is fast initially and slows as the shape of the amorphous zone becomes more regular. Only one regrowth rate is found for amorphous zones with a regular shape. The regrowth rate increased with decreasing energy below the threshold displacement voltage, suggesting that electronic excitations are able to induce epitaxial growth.
The Effect of Impurity Content and Ion Mass on the Depth Profiles of Vacancy-Type Defects in MeV Implanted Si
Authors: Libertino S. , Coffa S. , Privitera V. , Priolo F. 
Published: April 2011

AbstractWe used deep level transient spectroscopy to determine the concentration and depth profile of the defects introduced by MeV He and Si implants in n-type crystalline Si. We have found that only ˜ 16% of the Frenkel pairs generated by the ion escapes recombination and is stored into room temperature stable defects such as divacancies and oxygen vacancy complexes. For a light ion (He), the depth distribution of these defect complexes is strongly dependent on the O content of the substrate: it mirrors the initial distribution of I–V pairs, as calculated by TRIM (a Monte Carlo Code) when the O content is high (˜1018/cm3) while it can be much wider (up to 2 μm) in a highly pure (low O content) epitaxial substrate. This effect is due to a long range migration of vacancies before clustering or trapping at impurities. This migration is strongly inhibited for an ion of higher mass (such as Si) since in a denser collision cascade direct clustering is strongly favoured with respect to agglomeration of migrating defects.
Diffuse X-Ray Scattering Study of Defects Created by KeV Ion Implants In Si
Authors: Partyka P. J. , Averback R. S. , Nordlund K. , Robinson I. K. , Walko D. , Ehrhart P. , Diaz de la Rubia T. , Tang M. 
Published: April 2011

AbstractDiffuse x-ray scattering (DXS) and computer simulation techniques were employed to investigate the defect structure produced in Si by low keV ion and MeV electron irradiations. DXS measurements were performed for keV Ga and He implants, demonstrating the ability of the technique to provide both bulk and near-surface measurements at defect concentrations of about 1000 ppm. A rigorous analysis of these results is complicated due to the complex nature of the ion damage in Si. A computer simulation framework is developed to aid in the analysis of this data. In this technique, defects are simulated and their strain fields are calculated by simply relaxing the atoms around the defect to their equilibrium positions. The diffuse scattering is then calculated from the strain field, and the results are compared to the experimental measurements. Computer simulations are presented here only for the case of electron irradiation damage and compared to published measurements. Application of the technique to more complicated structures is planned and should pose no serious problems in the computational framework already developed.
Fluorescence Imaging of the Aluminum Oxide Transformation on the Surface of Single Crystal (111) NiAl
Authors: Schaffer H. E. , Lipkin D. M. , Adar F. , Clarke D. R. 
Published: April 2011

AbstractMicroscopic examination of the surface of single crystal (111) NiAl during various stages of oxidation at 1100 C in air shows the development of islands composed of rings of different colors.These islands appear to grow in size and eventually impinge with increased exposure. Microscopic fluorescence mapping of the surfaces of three single crystals subjected to varied exposure times provides an identification of the composition of the islands and the surrounding area as two different allotropes of alurninum oxide.Additionally, analysis of the map spectra demonstrates the decrease of intensity of their characteristic fluorescence bands in the island centers with increasing island size, which we refer to as “volcanic” intensity topography. Thus, the observed color variation is an interference effect, due to varied films thicknesses through the islands. Finally, the energies of the fluorescent bands are seen to shift as a function of distance from the island center, indicating the development of strain gradients across the islands.
Nucleation on Defects in Heteroepitaxy
Authors: Venables J. A. 
Published: April 2011

AbstractThe rate equation treatment of nucleation and growth on perfect substrates has been extended to cover nucleation on random defect sites, and problems involving 1-dimensional (1D) diffusion to sinks. This paper recaps the results of rate equation treatments on perfect terraces, and sumnarises some new models, including: 1) nucleation on point defects, with application to nm-sized Fe and Co particles grown on various CaF2substrates; 2) nucleation and diffusion in finite 1D deposits, with application to diffusion over, and the break-up of, multilayer deposits of Ag/Ge(111) and Ag/Fe(110); 3) 1D models developed for nucleation in competition with step capture. Comparison of rate-diffusion equations with experiment can result in values for, or bounds on, the controlling energies, in a way which illuminates the main features of interatomic forces at surfaces. The use of defects to grow thin film arrays for practical application presents some interesting challenges at both the nucleation and growth stages, which are discussed briefly.
Effects of Hydrogen on Nucleation of Islands During Si(001) Mbe Growth
Authors: Mizushima Kazuki , Šmilauer Pavel , Vvedensky Dimitri D. 
Published: April 2011

AbstractKinetic Monte Carlo simulations with two species (Si and H) have been performed to identify the mechanism behind the H-induced creation of a strongly temperature-dependent high density of Si islands in the temperature range of 300–550 K during molecular-beam epitaxy on Si(001) surface. A model is proposed to explain this effect as a result of an activated exchange between H and Si at Si island edges.
The As-Grown Microtopologies of Modified-Lely SiC(0001) Terraced Vicinal Surfaces
Authors: Marek T. , Heindl J. , Strunk H.P. , Eckstein R. , Müller St.G. , Hofmann D. 
Published: April 2011

AbstractRisers and treads on terraced surfaces of modified-Lely (M-Lely) grown 6H-SiC(0001) bulk crystals are investigated by reflection electron microscopy (REM). On risers we find parallel steps, with a height of one or two unit cells. On treads we find in addition to growth spirals island formation. We take these observations to conclude that two competitive processes operate in parallel, the step-flow mode and the two-dimensional nucleation.
Structural and Morphological Characterization of Ultrathin Films of an Asymmetric Polydiacetylene
Authors: Wang H. C. , Cheong D. W. , Kumar J. , Sung C. , Tripathy S. K. 
Published: April 2011

AbstractA soluble, asymmetrically substituted polydiacetylene, poly(BPOD), has been reported to form stable monolayers at the air-water interface by the Langmuir-Blodgett (LB) technique [2]. Preformed polydiacetylene has been deposited onto hydrophobic substrates as multilayers to form second order nonlinear optical thin films. Second harmonic generation was found to increase with the number of layers. From previous atomic force microscopy (AFM) studies backbone orientation along the dipping direction with an interchain spacing of about 5 A° was indicated [2].The film morphology and preferential molecular orientation of these LB films are further investigated by transmission electron microscopy (TEM). A specifically tailored sample preparation method for the ultrathin LB films was used. Multilayer films were deposited on hydrophobic collodion covered glass substrates for this purpose. Electron diffraction was employed to study the crystalline organization of mono and multilayers of LB films as well as cast films.
Exact Scaling Form for the Island Size Distribution in Submonolayer Epitaxial Growth
Authors: Bartelt M. C. , Evans J. W. 
Published: April 2011

AbstractThe exact scaling form is determined for the size distribution of islands created via irreversible nucleation and growth during submonolayer deposition. This form is controlled by a dependence on size of the propensity for islands to “capture” diffusing adatoms. This sizedependence is determined directly from simulations. It reflects a complex relationship between the size of an island, and the area of its cell in a tessellation of the surface based on the island locations. The relationship corresponds to a correlation between island size and separation.
Step Contours in the Development of Periodically Modulated Vicinal Surfaces
Authors: Tanaka S. , Umbach C. C. , Blakely J. M. , Tromp R. M. , Mankos M. 
Published: April 2011

AbstractThe connection between the atomic step distributions and decay modes of modulated surfaces is the focus of this paper. We have examined the arrangements of atomic steps on real 1- and 2-D periodic structures by scanning tunneling microscopy(STM) and low energy electron microscopy(LEEM) and have followed their development at temperature by LEEM. The steps present on the surface due to small ‘miscuts’ from exact singular planes can have major effects on both the mechanisms of shape development and the actual shapes that result. Major differences exist in the modes of development between 1- and 2-D periodic step arrays. Some of these observations have led us to a method for producing arrays of step-free Si(001) regions that may have application in device processing.
Surface Morphology of Si1−x−y GexCy Epitaxial Films Deposited by Low Temperature UHV-CVD
Authors: John S. , Quinones E. J. , Ferguson B. , Ray S. K. , Mullins C. B. , Banerjee S. K. 
Published: April 2011

AbstractSi1−x−y GexCy epitaxial films offer wider control of strain and bandgap. In such films the morphology is an important indication of the crystalline quality of the material. We report on the morphology of Si1−x−y GexCy epitaxial thin films deposited by Ultra High Vacuum Chemical Vapor Deposition at a temperature of 550° C and deposition pressures ranging from 1 to 10 mTorr. The precursors used were Si2H6, GeH4 and CH3SiH3. Germanium mole fractions ranging from 0% to 40% were studied with carbon concentrations varying from 2×1019 to 2×1021 atoms/cm3. AFM analysis of the surface indicates that the roughness is a function of both the carbon concentration and the film thickness. For high germanium concentrations with thickness beyond the critical thickness (of Si1−xGex), carbon is found to decrease the surface roughness of the film. Thus the surface morphology confirms the strain compensation provided by carbon which is also observed using XRD. For films below the critical thickness, as the carbon concentration is increased, three dimensional islanding is observed by RHEED and AFM, degrading the epitaxial quality of the material.
The Formation and Evolution of InAs 3D Islands on GaAs(001) and a Comparative C-AFM and NC-AFM Study of InAs 3D Islands
Authors: Ramachandran T. R. , Kobayashi N. P. , Heitz R. , Chen P. , Madhukar A. 
Published: April 2011

AbstractThe two-dimensional (2D) to three-dimensional (3D) morphology change in the highly strained growth of InAs on GaAs(001) is examined via in-situ, ultra-high vacuum (UHV) scanning tunneling microscopy (STM) and contact-mode atomic force microscopy (C-AFM). The formation of 3D InAs islands (˜2–4nm high) at an InAs delivery, θ˜1.57ML is found to be preceded by the appearance of small quasi-3D clusters (˜0.6–1.2nm high). The 2D to 3D transition is found to occur over a range of θ from ˜1.45ML to 1.74ML, with a varying and gradual mass transfer from 2D to 3D features with increasing θ. The InAs 3D islands are also examined in this study using non-contact AFM (NC-AFM) in order to assess the usefulness of this technique for imaging 3D features. Unlike the constancy observed in the C-AFM images, the NC-AFM images exhibit a marked imaging condition dependence. The variability observed in the NC-AFM images is qualitatively compared to the outcome of the simplest, force-gradient model of NC-AFM in order to extract a guideline for NC-AFM imaging of 3D features.
The Morphological Stability of Strained Epitaxial Layers
Authors: Wessels B. W. 
Published: April 2011

AbstractThe morphological stability of strained-layer thin films is analyzed using classical nucleation theory. For the case where strain relaxation occurs by formation of coherent islands, the model predicts that the critical thickness for transition from two-dimensional (2D) to three dimensional (3D) growth depends inversely on the square of the misfit. The predicted dependence of critical thickness on misfit is in agreement with recent experimental studies on the heteropitaxy of III-V compounds.
A 3-D Kinetic Monte Carlo Study of the Growth of Si Thin Films Using Beams With Varying Angle of Incidence
Authors: Levine S.W. , Engstrom J.R. , Clancy P. 
Published: April 2011

AbstractThree-dimensional Kinetic Monte Carlo simulations were used to model the deposition of a hyperthermal molecular beam at varying angles of incidence. The simulations incorporate incident atom-substrate interactions, many layer growth, and attempt to mimic deposition and growth of Si on a Si(100) substrate. At high angles of incidence, the formation of “flake”-like structures are seen. The growth of the flakes follow the same general trends as previous two-dimensional simulations where non-local shadowing produces a porous thin film and the columns grow into the incident beam. Increased substrate temperature increased the widths of the flakes perpendicular to the path of the beam and allowed the grown film to remain defect-free for a time before columnar structure begins.
Roughening and Preroughening of Diamond-Cubic {111} Surfaces
Authors: Woodraska Donald L. , Jaszczak John A. 
Published: April 2011

AbstractUsing a new solid-on-solid model that correctly takes into account the diamond-cubic crystal structure, both a roughening transition at temperature TR and a distinct preroughening transition at TPR≈0.43TR are found to exist on {111}surfaces of diamond-cubic materials. Results are presented for height-difference correlation functions, surface specific heats, step energies, etch rates, and a preroughening order parameter. Preroughening appears to arise naturally in our nearest-neighbor bond model from the entropic freedom available in the non-trivial crystal structure suggesting that preroughening may be more common than previously anticipated. Preroughening is shown to dramatically lower step energies and step-energy anisotropy on the {111} surface.
Preroughening of Si{111} may have been seen in experiments by Noh et al. [Phys. Rev. B 48, 1612 (1993)].
Characterization Of Grown-In Defects In CZ-SI Crystals By Bright Field IR Laser Interferometer
Authors: Nakai Katsuhiko , Hasebe Masami , Iwasaki Toshio , Tsumori Yasuo 
Published: April 2011

AbstractWe have developed a quantitative measurement method for the number density, size and morphology of grown-in defects in czochralski-grown silicon (CZ-Si) crystals with a bright-field infrared-laser interferometer (known as Oxygen Precipitate Profiler; OPP). Using this method we investigated the effect of crystal cooling condition during crystal growth on the formation of grown-in defects by growth holding experiments. The relation between gate oxide integrity (GOI) and grown-in defects was studied. It was revealed that the grown-in defects have octahedral shape and degrade the GOI performance. We estimate the density as well as cumulative volume of the grown-in defects and discuss the formation mechanism of them.
Tem Observation Of Grown-In Defects In CZ-Si Crystals And Their Secco Etching Properties
Authors: Kato Masahiro , Takeno Hiroshi , Kitagawara Yutaka 
Published: April 2011

AbstractGrown-in defects detected by IR laser scattering tomography (LSTDs) in Czochralski-grown Si crystals were identified by transmission electron microscopy (TEM) with a special defect positioning technique. The basic structure of the LSTD was revealed to be a composite of two or three incomplete octahedral voids with the 100–300nm total size. The TEM images of the defect showed existence of 2∼4nm-thick walls surrounding the voids. These thin-walls are considered to be made of oxide, SiOx. These LSTDs are indeed dominant grown-in defect species in most of the commercial CZ-Si walers. The LSTD after 1200°C oxidation was also observed by TEM. The resulting image shows that the defect changed from void to filled oxide precipitate by the high temperature heat treatment. On the other hand, in very slowly pulled crystals with ∼0.4mm/min rate, interstitial type dislocation loops were observed as major defect species. Non-agitated Secco etching of these grown-in defects delineates “flow patterns” (FPs) or pits without the flow patterns. The FP forming property is shown to disappear by oxidation at temperature above 1150°C, while the defect itself remains stable. This implies that the grown-in defects lose their chemical properties to form FPs by the high-temperature oxidation. It is further revealed that the grown-in defects, which once lost the FP forming property by the high-temperature oxidation, can form FPs again by an intentional Cu contamination. Thus a possible FP formation factor is Cu decoration at the grown-in defect site. Defect formation model of the as-grown twin-type LSTD is also proposed.
Crystallographic Analysis Of Flow Pattern Defects In Dislocated Czochralski Silicon Crystals
Authors: Ikematsu Y. , Iwasaki T. , Harada H. , Tanaka K. , Fujinami M. , Hasebe M. 
Published: April 2011

AbstractIn dislocated Cz-Si crystals, rows of flow patterns (FP) and Secco etch pits (SEP) (2–3 mm in length, along <110> direction) can be revealed by Secco etch without agitation. In this study, the crystal defects forming FP-SEP rows in dislocated Cz-Si crystals are investigated by transmission electron microscopy. Microdefects, 0.1 μm in size, are observed in a row along a FP-SEP row, <110> direction. These defects were identified as oxygen precipitates with or without dislocation loops (interstitial-type), and voids with oxidized interiors. We conclude that FP originate from interstitial-type dislocation loops, and SEP are due to oxygen precipitates or voids.
Enhanced Dissolution Of Extrinsic Dislocation Loops In Silicon Annealed In NH3
Authors: Herner S. B. , Krishnamoorthy V. , Jones K. S. , Mogi T. K. , Gossmann H.-J. 
Published: April 2011

AbstractThe behavior of extrinsic dislocation loops in silicon was investigated by transmission electron microscopy. Loops were formed by an amorphizing implant and recrystallization anneal of Si wafers. Wafers were further annealed in either Ar or NH3. Wafers annealed in NH3 formed a thin (∼4 nm) SiNx film. The loops in samples in Ar showed a constant net number of interstitials bound by the loops, while those in samples annealed in NH3 showed a marked decrease. The results are explained by a supersaturation of vacancies recombining with the interstitials in loops. By integrating the measured difference between interstitials bound by the loops in samples annealed in Ar vs. NH3 over the distance from the surface to the loop layer, an estimate for the relative vacancy supersaturation is extracted. Comparison with estimates of vacancy supersaturations with nitridation from the change in Sb diffusivity show good agreement between the two methods.
Cooperative Chemical Rebonding In The Segregation Of Impurities In Silicon Grain Boundaries
Authors: Maiti A. , Chisholm M. F. , Pennycook S. J. , Pantelides S. T. 
Published: April 2011

AbstractWith ab initio calculations we show that the experimentally observed large segregation energies of As at Si grain boundaries can be explained by the formation of isolated dimers or ordered chains of dimers of threefold-coordinated As along the cores of grain boundary dislocations. We also find the intriguing possibility that As segregation may drive structural transformation of certain grain boundaries. Recently we have obtained the first atomic-resolution STEM images of As in a Si grain boundary, consistent with the formation of As dimers. Segregation energy of As dimers was found to be significantly higher in isolated dislocation cores, where larger site-variation in strain than in grain boundaries lead to further lowering of the electronic levels of As deep into the bandgap.
Formation Of Hydrogen Molecules In Crystalline Silicon Treated With Atomic Hydrogen
Authors: Murakami K. , Fukata N. , Sasaki S. , Ishioka K. , Nakamura K. G. , Kitajima M. , Fujimura S. , Kikuchi J. , Haneda H. 
Published: April 2011

AbstractHydrogen molecules have been formed in crystalline silicon at various temperatures by a hydrogen-atom remote treatment. The Raman spectrum of the vibrational lines of hydrogen molecules in crystalline silicon is detected for silicon samples treated at temperatures between 250 and 500° C. The maximum production is obtained at 400° C. The Raman spectrum of hydrogen molecules in silicon observed at room temperature exhibits a frequency shift of around 4158 cm−1 and a very broad half-width of approximately 34 cm−1. Isotope shift also can be observed at around 2990 cm−1 in silicon treated with deuterium atoms at 400° C. The frequency shifts of the observed lines are in close agreement with those reported for molecular hydrogen and deuterium in gas, liquid, and solid phases. We discuss a model for the hydrogen molecule configuration and rule out the possibility of high-pressure hydrogen molecular gas in microvoids in crystalline silicon. These results indicate that hydrogen molecules exist at the tetrahedral interstitial sites in crystalline silicon.
Dislocation Velocities In Gesi Bulk Alloys
Authors: Yonenaga I. 
Published: April 2011

AbstractThe mechanical strength and dislocation velocities in single crystal Ge1−xSix alloys grown by the Czochralski method were investigated by compressive deformation and by the etch pit technique, respectively. In the temperature range 450 – 700 °C and the stress range 3 – 20 MPa, the dislocation velocity in the GeSi alloys with x = 0.004 – 0.053 decreases monotonously with an increase in the Si content, reaching about a quarter of that in Ge at x = 0.053, and can be expressed as a function of the stress and the temperature. The yield stress of the GeSi alloy increases with increasing Si content from x = 0 to 0.4 and is temperature-insensitive at high temperatures, showing that the flow stress of alloy has an athermal component which is absent in elemental or compound semiconductors.