bluuebunny/crossref_metadata_2025_split huggingface dataset:
Delineation of p-n Junctions on Cross Sectional TEM Device Samples
Authors: Knoesen Dirk , Zhang Fang , Rozgonyi George A. 
Published: March 2011

ABSTRACTThe delineation of n-p junctions is one of the techniques routinely required in the analysis of electronic devices. The delineation of the junction profile is typically done either in a scanning electron microscope (SEM) or by angle lapping / staining/ optical microscopy. Recently TEM foils have been selectively etched to simultaneously provide an interface demarcation and an image of processed induced dislocations. A case study is presented in this report on concentration dependent delineation techniques with emphasis on the special problems associated with cross sectional transmission electron microscopy (XTEM) samples. The etchants used in delineating junctions for the SEM or with angle lapping / optical microscopy of transistors are too aggressive for the extremely thin TEM foils. This paper discusses etchants which deliver reproducible, high contrast delineations in XTEM samples with known concentration profiles.
Ultramicrotomy for Materials Science
Authors: Malis T. F. , Steele D. 
Published: March 2011

ABSTRACTDiamond knife sectioning, or ultramicrotomy, is being used increasingly as an attractive alternative or complimentary means of producing quality TEM specimens. This paper represents a first attempt to provide a basic methodology for this technique for materials scientists, point out its drawbacks, provide a comprehensive listing of more than three decades of widely-scattered and ingeneous applications, and illustrate the diversity of these applications with clear examples. Suggestions will be made for further improvements in ultramicrotomy so that it can be applied in a more routine fashion to modern advanced materials or TEM applications involving demanding chemical microanalysis.
Improved Methods and Novel Techniques for Jet Electropolishing of TEM Foils
Authors: Kestel Bernard J. 
Published: March 2011

ABSTRACTExperience has shown that the difficulties encountered in jet polishing of TEM foils can be minimized by the selection of equipment and an electrolyte appropriate for each material. The use of a jet polishing instrument for more than one type of specimen preparation after minor modification will be presented. Some insights on the relationship and manipulation of the parameters involved in achieving well polished TEM foils having appropriate surface quality, thin area, and perforation size will be included. Methods used to develop new electrolytes for specific purposes and the results of their use on both conventional and superconducting materials will be shown. A technique to calibrate equipment for more reproducible specimen hole size, use of new electrolytes on various materials, the salvage of unsatisfactory foils, and thinning of undersized specimens will be reviewed.
Mechanical Polishing to Submicron Thickness for Extensive Thin Area in Heterogeneous Samples
Authors: Dawson-Elli David F. , Turowski Marek A. , Kelly Thomas F. , Kim Yeon-Wook , Zreiba Nuri A. , Chen-Ming Tens , Mei Zhou 
Published: March 2011

ABSTRACTIon-milling-based sample preparation has the advantage that thin area can be obtained from almost any material. It has the disadvantage, however, that the amount of thin area can often be quite limited. This poses a problem when a large sampling area is needed from materials which must be thinned by ion milling. Cross-sectioned samples and grossly heterogeneous materials are two examples where this problem may be encountered. The group at IBM in East Fishkill have developed methods for mechanical grinding and polishing of TEM samples down to about I micron thickness. They use this as a starting point for final thinning by ion milling. This approach produces a large uniform thin area in a short time in the ion mill. We have built jigs that allow us to make these mechanically-thinned samples. We have also made flat-bottomed dimples using ultra-precision dimple grinders to achieve similar results. Both of these approaches are described. Examples are taken from cross-section samples of thin films on silicon, from steels with large carbides, and from rapidly solidified metal spheres embedded in electroplated copper.
Application of Channeling to Defect Studies in Crystals
Authors: Chu W. K. 
Published: March 2011

ABSTRACTChanneling of fast, light ions in crystals has been widely used as a tool for studying crystal defects. Backscattering yield measurement on ions incident along major axial or planar crystalline directions provides information on the depth distribution of the structural defects in the first few microns. The channeling technique in defect detection is not as sensitive as Transmission Electron Spectroscopy, nor is it accurate in measuring the absolute numbers of defect density. Channeling measurements can give only an indication of the degree of lattice disorder. It is possible to distinguish one type of defect from another by carefully studying the energy dependence of the dechanneling. The dechanneling interpretation is not always unique, and in practice it is difficult to obtain structure information through that method. Despite these negative qualities, channeling is an attractive and unique method in certain defect studies. For example, it is sensitive for studying the lattice location of impurity atoms at substitutional or interstitial sites. Clustering of substitutional impurity atoms will show a displacement of the impurity atoms from lattice sites due to the change of bond distance. Channeling is sensitive for measuring impurity displacement as small as 0.1A°. This has been demonstrated in the study of arsenic clustering formation in Si. Interfacial relaxation and contraction in a multi-layered structure made by molecular beam epitaxy has been detected by dechanneling along various axial directions. Channeling study on surface and interface structures has developed over the past few years. In this paper, I will use examples to illustrate the unique features of the channeling technique and its application to defect studies in single crystals.
Detection of Point Defect Chains in Ion Irradiated Silicon by High Resolution Electron Microscopy
Authors: Krakow W. , Tan T.Y. , Foell H. 
Published: March 2011

ABSTRACTIn a lattice imaging study of As+ ion damaged Si, we have detected =110> chain type defects which are not associated with any significant strain or configurational changes. By image matching of the experimental and calculated micrographs of vacancies and interstitials, it is established that about 100% more interstitial atoms may incorporate into a defective chain. A structure model of this defect is proposed wherein a di-interstitial, occupying the =100> split position, is incorporated into every available site along a =110> chain.
Transient Capacitance Studies of a Low-Lying Electron Trap in n-type Silicon
Authors: Jellison G. E. , Cleland J. W. , Young R. T. 
Published: March 2011

ABSTRACTA new electron trap has been observed in electronirradiated n-type silicon at Ec − ET = 0.105 eV using transient capacitance techniques. It is found that the maximum transient capacitance response is observed only when the majority carrier pulse width is much smaller than some characteristic time constant, and when the time between pulses is much larger than another characteristic time constant. It is shown that this defect is related to an electron trap at Ec−ET = 0.172 eV (probably the oxygenvacancy or A-center); it is believed that this trap is induced by the electric field found in the depletion region of a p-n junction.
Ebic Investigation of Hydrogen Passivated Structural Defects in Efg Silicon Ribbon
Authors: Sullivan T. D. , AST D. G. 
Published: March 2011

ABSTRACTEBIC contrast of structural defects in as-received and hydrogen passivated polysilicon ribbon is studied using aluminum Schottky barrier diodes. Enhanced charge collection after passivation is demonstrated by comparing the EBIC signal from two sections of a split ribbon, one half of which was passivated. Electrical activity of specific linear defects before and after passivation is examined by recording charge collection profiles across these defects under standardized conditions of beam voltage and current. Such measurements show that passivation does reduce the electrical activity of selected defects. Possible reasons for this behavior will be discussed.
Real-Time X-Ray Topographic Observation of Melting and Growth of Silicon Crystals
Authors: Chikawa Jun-Ichi , Sato Fumio 
Published: March 2011

ABSTRACTA technique for the direct viewing of topographic images was developed based on a television system using an x-ray sensing PbO-vidicon camera tube (resolution 25 μm). Melting and growth processes of plate-shaped crystals were observed in an argon flow by this technique. The observation showed that dislocations have very high mobilities by superheating and the equilibrium dislocation density of zero is achieved just before melting. In melting of dislocation-free crystals, liquid drops (locally molten regions) were observed inside the crystals. While, crystallites appeared in the supercooled melt near the growth interface. It was found that both the drops and crystallites are not formed in 5% hydrogen/95% argon environment. Melting behavior of crystals covered with oxide films indicates that the solid-liquid interfacial free energy is greatly lowered by oxygen impurity. This oxygen effect may be responsible for both the drop and crystallite formation. Origin of swirl defects in dislocation-free crystals is discussed in the basis of these observations. Both composite and common a/2<110> dislocations were observed near the growth interface: The former are composed of three a/2<110> dislocations and are present at the interface so that, as the crystal grows, they propagate into the new crystal. They influence the interface morphology, when their Burgers vectors have the component perpendicular to the interface. The common dislocations cannot exist stably at the interface and are driven into the newly grown dislocation-free region by thermal stresses.
Analysis of Defects in Laser Annealed GaAs
Authors: Fletcher John , Narayan J. , Lowndes D. H. 
Published: March 2011

ABSTRACTThe nature and depth distributions of residual damage in ion implanted and pulsed ruby laser annealed GaAs have been studied using both plan-view and cross-section transmission electron microscopy (TEM) specimens for high dose (1.0 × 1015 cm−2) Zn+, Se+ and Mg+ implants. It was found that laser energy densities above 0.36 J/cm2 were required to remove the implantation damage, this threshold energy density giving good agreement with that indicated by electrical activation measurements. Laser induced surface degradation of the GaAs was present even for energy densities as low as 0.25 J/cm2, and more severe damage, with the introduction of dislocations near the surface, was present for energy densities above 0.8 J/cm2. The use of thin SiO2 layers for encapsulation during laser annealing was found to substantially reduce this surface degradation.
Scanning Cathodoluminescence Microscopy of Polycrystalline GaAs
Authors: Salerno Jack P. , Gale Ronald P. , Fan John C. C. , Vaughan John 
Published: March 2011

ABSTRACTScanning cathodoluminescence microscopy (SCM) has been used for nondestructive characterization of the optoelectronic properties of heavily Zn-doped, Bridgman-grown polycrystalline GaAs. Grain boundaries can either show no cathodoluminescence contrast, appear as dark lines, or appear slightly brighter than the surrounding matrix. Boundaries with similar surface morphologies can show different contrast. Spectral analysis data indicate that many of the observed features are due to local variations in impurity concentration.
Ion Channeling Techniques for Defect and Surface Studies
Authors: Appleton B. R. 
Published: March 2011

ABSTRACTThe channeling and blocking phenomena are well enough understood that they can be combined with ion scattering or ion induced reactions to investigate defects and surface structures. A brief review is given of the origins of these phenomena, of associated concepts which are useful for defect and surface analysis, and of experimental constraints and requirements. Applications to selected problems are used to illustrate the advantages and limitations of these techniques.
Density Functional Theory of Interplane Cohesion in Graphite and Graphite Intercalation Compounds
Authors: Divincenzo D.P. , Mele E.J. 
Published: March 2011

ABSTRACTWe employ density functional theory to study structural energies in pure graphite, Li-graphite, and K-graphite. Qualitative agreement with experiment is obtained for the carbon plane binding energy, lattice constants, compressibilities, and in-plane alkali-alkali potentials.
Change of C–C Bond Length in Layers of Graphite Upon Charge Transfer
Authors: Kertesz Miklos , Vonderviszt Ferenc , Hoffman Roald 
Published: March 2011

ABSTRACTTight binding crystal orbital calculations on infinite layers of graphite have been performed for charge transfer (q) values ranging from −0.15 to +0.15 e/carbon atom. The rC-C carbon-carbon bond lengths have been optimized at several q values. The change of the calculated rC-C values as a function of q fits very well with the experimentally observed variations of the C-C bond lengths of both acceptor and donor compounds of intercalated graphite. The asymmetry of the variation of rC-c with respect to the sign of the charge transfer is related to the slightly antibonding nature (at the level of second neighbor interactions) of the π-electrons around the Fermi level of pristine graphite, similar to those in polyacetylene.
C-Axis Resistivity Of Some Stage 1 Donor Compounds
Authors: Fischer J.E. , Fuerst C.D. , Kim H.J. 
Published: March 2011

ABSTRACTTemperature-dependent c-axis resistivity measurements on LiC6, KC8, RbC8, CsC8 with and without substitutional boron in the starting material, and KHgC4 are presented. The overall behavior is metallic except for the MC8 compounds below 50-100K where Pc increases with decreasing T. This effect appears to be an intrinsic property of stage 1 materials with commensurate 2×2 superlattices.
Superconductivity and Intralayer Structure in Potassium Amalgam-Gic
Authors: Timp G. , Elman B.S. , Dresselhaus M.S. , Tedrow P. 
Published: March 2011

ABSTRACTWe report on the structural, lattice and electronic properties of stage 1,2,3 potassium-amalgam GIG and the relation of these properties to the observed superconducting transition temperature. The ultramicrostructure of the intercalant domains is investigated using lattice fringe imaging. Our observation of macroscopic (√3×√3),(2×2) and (√3×2) domains is consistent with the basal plane zonefolded phenomena observed in the Raman spectra. Shubnikovde Haas measurements of the Fermi surface show high frequency (>1000 T) oscillations in stage 2, identified with the intercalant band.
Susceptibility of Magnetic Graphite-CoCl2Intercalation Compounds
Authors: Elahy M , Dresselhaus G. 
Published: March 2011

ABSTRACTPrecise measurements of the temperature dependence of the magnetic susceptibility for stage 2 and 5 graphite-CoCl2intercalation compounds are reported. Comparison of the experimental results with theoretical calculations based on a two-dimensional planar model show agreement with theory, suggesting that graphite intercalation compounds represent ideal two-dimensional magnetic systems.
Metal Chloride-Graphite Compounds as Cathode and Anode Materials For Batteries
Authors: Flandrois Serge , Baron Francis 
Published: March 2011

ABSTRACTGraphite intercalation compounds can be used as electrode materials in batteries owing to the high electronic conductivity of carbon layers and the easy diffusion of ions between the layers. Moreover intercalation has the beneficial effect of impeding some parasitic reactions detrimental to good electrode reversibility. After a brief review of recent proposals, emphasis is given to transition metal chlorides. It is shown that, besides the nickel chloride-graphite compound proposed two years ago as a cathode material for alkaline batteries, other metal chlorides intercalated into graphite are excellent cathode or anode materials.
Staging Transitions In Li-Graphite : Phonon Spectra Of Dilute Stage 1
Authors: Woo K.C. , Mertwoy H. , Fischer J.E. , Kamitakahara W.A. , Robinson D.S. 
Published: March 2011

ABSTRACTFirst-order transitions to dilute stage one from stages 2,3 and 4 and from mixed stage 1+2 are observed in Li-graphite as predicted by Safran. The upper phase boundary is asymmetric in concentration and is sharply peaked about x ∼ 0.4. The phonons in the dilute stage 1 have energies between those of LiC6 and graphite. Unlike the stage 2 compounds, the compressibility does not scale in a simple way with intercalant density.
Single-Crystal X-Ray Scattering Study of Superstructures and Phase Transitions in Graphite-Hno3 and Graphite-Br2 Intercalation Compounds
Authors: Moret R. , Comes R. , Furdin G. , Fuzellier H. , Rousseaux F. 
Published: March 2011

ABSTRACTIn α-C5n-HNO3 the condensation of the room-temperature liquid-like diffuse ring associated with the disorder-order transition around 250 K is studied and the low-temperature. superstructure is examined.It is found that β-C8n-HNO3 exhibits an in-plane incommensurate order at room temperature.Two types of graphite-Br2 are found. Low-temperature phase transitions in C8Br are observed at T1 ≍ 277 K and T2 ≍ 297 K. The room-temperature structure of C14Br is reexamined. Special attention is given to diffuse scattering and incommensurability.
Lattice Dynamical Model for Graphite-Bromine Intercalation Compounds
Authors: Al-Jishi R. , Dresselhaus G. 
Published: March 2011

ABSTRACTA Born-von Kármán lattice dynamical model for the graphite Br2 intercalation compounds is presented. The low frequency bromine branches are calculated using a commensurate (√3 × √13)R(30°, 13.9°) unit cell with two Br2 molecules/unit cell. In-plane zone folding is used to calculate the high frequency graphitic modes at the Brillouin zone center.
Mixed Phonon Mode In C24Rb
Authors: Funahashi Satoru , Kondow Tamotsu , Iizumi Masashi 
Published: March 2011

ABSTRACTThe [001] L-mode phonon excitations of C24Rb were studied by neutron inelastic scattering in the region where the phonon dispersion curve of the acoustic branch anticrosses the transverse Einstein oscillation level. The interaction between the longitudinal collective mode and the transverse Einstein mode could be observed only in the temperature region where the rubidium atoms form an ordered structure. The mechanism of the interactions between the transverse and longitudinal modes is discussed in relation to the symmetry of the atomic position of rubidium.
NMR Spectroscopy of Synthetic Metals: Intercalated Graphite
Authors: Resing H. A. , Moran M. J. , Miller Gerald Ray , Banks L. G. , Poranski C. F. , Weber D. C. 
Published: March 2011

ABSTRACTNMR techniques have been used in graphite intercalation systems for chemical analysis and for determinations of structure, molecular dynamics, exchange kinetics, conductivity and electron concentration. Salient results will be presented. We have been most interested in understanding the reaction3AsF5 + 2Cn ⇋ 2CnAsF6 + AsF3 (1)for which a single, extremely narrow 19F NMR line is observed when AsF5 reacts with graphite. In contrast, when the reactionNO2AsF6(in CH3NO2) + Cn→NO2 ↑ + CnAsF6 (2)is carried out, followed by addition of the stoichicmetric amount of AsF3, separate spectra for the AsF6 (a broad doublet) and lor AsF3 (a sharp 1:2:1 triplet) are observed, indicating that these two species do not exchange fluorine atoms, and suggesting that eq. (1) is not reversible. The AsF3 triplet gives an order parameter for the molecular thrae fold axis with respect to the graphite c-axis. The carbon-13 spectrum for a fifth stage intercalate of HNO3 shows the 2:2:1 triplet expected if each kind of layer Is resolved.
13C NMR Chemical Shifts of Oriented Cesium-Graphite Intercalation Compounds
Authors: Dominguez D.D. , Resing H.A. , Poranski C.F. , Murday J.S. 
Published: March 2011

ABSTRACTThe 13C NMR lines of the stage I cesium graphite compound are broad (ca. 600 Hz) at all orientations, reflecting immobile Cs intercalation; in terms of an axial pattern the principal values are δ11 = 95 ± 5 and δ┴6 = 130 ± 6 ppm. For third and fourth stage compounds the bounding layers give a relatively sharp (60–100 Hz) pair of lines at all orientations, thus demonstrating axially symmetric shift tensors: δ11 = 66 and 56 ppm; δ┴ = 159 and 149 ppm, respectively. These well defined axial tensors reflect atomic motions in the incommensurate Cs layer; the pair of lines may arise from the two classes of carbons - those above carbons in a subsequent layer and those above hexagon centers. Lines of inner layers are sharpest for special orientations →c II →B0 and →c ┴ →B0.
Disorder in Staging of Potassium Graphite: Fractional Stage 3/2 and STAGE 7
Authors: Fuerst C.D. , Koch T.C. , Fischer J.E. , Axe J.D. , Hastings J.B. , McWhan D.B. 
Published: March 2011

ABSTRACTAt high pressure KC8undergoes a staging transition to a mixture of stages 1 and 3/2 at 15 kbar and stages 1 and 2 at 19 kbar. The width of the new peaks are not resolution limited but show a pronounced and non-monotonic variation with Q. This broadening is the result of a finite concentration of staging defects which can be simply modeled by stochastic disordering of an appropriately chosen two component layer sequence. This same analysis has also been used to explain deviations from the Bragg locations in KC84.
A Study of the Electrical and Mechanical Properties of Alkali Metal Intercalated Graphite Fibers
Authors: Dominguez D.D. , Lakshmanan J.L. , Barbano E.F. , Murday J.S. 
Published: March 2011

ABSTRACTIndividual graphite fibers (TP 4104B and GY-70) were intercalated with alkali metals using the two-zone vapor transport method commonly used to prepare alkali metal intercalated graphite. The progress of the reaction was followed in situ by measuring the electrical resistances of the fibers as the temperature difference (ΔT) between the fiber and the metal was decreased stepwise. These measurements showed that the ease and extent of intercalation are related to fiber graphitization. Without exposure to air, the temperature dependence of the resistances of the intercalated fibers were also measured from −196°C to 400°C. The measurements showed that the intercalated fibers have a metallic dependence on temperature. Tensile strength measurements on the intercalated fibers showed that intercalation of the heavy alkali metals is deleterious.
Optical Reflectance Studies of the Stage 1 and 2 Potassiummercurographitides in the Energy Range 0.16-5.8 eV
Authors: Heinz R.E. , Eklund P.C. 
Published: March 2011

ABSTRACTReflectance spectra of the stage 1 and 2 compounds of graphite intercalated with Hg-K amalgam are reported for the range (0.2-5.8eV). A Kramers-Kronig analysis was performed on the spectra to determine the dielectric function ∊1(ω) and ∊2(ω). The intraband and interband contributions to ∊(ω) have been separated to determine the plasma frequency and free carrier lifetime.
Optical Reflectance Studies of Stage 1-6 Graphite-Fecl3Intercalation Compounds
Authors: Smith D. S. , Eklund P. C. 
Published: March 2011

ABSTRACTResults of Optical Reflectance measurements on stage 1-6 graphite-FeCl3intercalation compounds are reported. The frequency dependences of the dielectric constants(∊1, ∊2) are determined. The contributions from free carrier and interband absorption are separated to determine important material parameters.