bluuebunny/crossref_metadata_2025_split huggingface dataset:
In situ observations of electromigration induced void behavior
Authors: Marieb T. , Bravman J. C. , Flinn P. , Gardner D. , Madden M. 
Published: June 2020

Electromigration and stress voiding have been active areas of research in the microelectronics industry for many years. While accelerated testing of these phenomena has been performed for the last 25 years[1-2], only recently has the introduction of high voltage scanning electron microscopy (HVSEM) made possible in situ testing of realistic, passivated, full thickness samples at high resolution.With a combination of in situ HVSEM and post-testing transmission electron microscopy (TEM) , electromigration void nucleation sites in both normal polycrystalline and near-bamboo pure Al were investigated. The effect of the microstructure of the lines on the void motion was also studied.The HVSEM used was a slightly modified JEOL 1200 EX II scanning TEM with a backscatter electron detector placed above the sample[3]. To observe electromigration in situ the sample was heated and the line had current supplied to it to accelerate the voiding process. After testing lines were prepared for TEM by employing the plan-view wedge technique [6].
High-resolution TEM and energy filtering TEM study of interfacial structure and reaction of diamond/Si in chemical vapor deposition
Authors: Chen Fu-Rong , Chang L. , Chen C. J. , Lin T. S. 
Published: June 2020

Diamond film was grown using microwave plasma CVD technique which consists of three steps: carburization, bias and growth . The high resolution TEM (HRTEM) in cross-sectional view has been used to observe the evolution of interfacial structure in each processing step [1]. The chemistry near the interface was characterized with elemental mapping using energy-filtered imaging technique with Gatan imaging Filter (GIF) [2]. At the carburization stage, β-SiC, diamond particles and graphite plates have been observed in an amorphous layer. This amorphous layer was analysized to be carbon by energy filtering technique.As shown in the Fig. 1, β-SiC can form in epitaxial orientation with Si in the following stage of biasing. Graphite was not observed after the bias was applied. At the bias stage there is an interlayer of 6 nm thick between diamond and silicon substrate . From the high resoultion image in Fig. 2 (a), most of the regions of the interlayer are of amorphous characteristics which presents a barrier to identify the elemental compositions.
Interface analysis in the VG microscopes’ HB603 300 keV STEM
Authors: Bruley John , Ackland David W. , Fang Jianxin , Williams David B. 
Published: June 2020

The optimum operating conditions for microanalysis (either EDX or EELS) would be those which maximize the signal-to-noise ratio, SNR, and signal-to-background ratio, SBR, and at the same time minimize the probe size so as to locate the signal to as small a volume as possible. In practice however these three quantities can not be optimized simultaneously. For many materials problems, the analyst seeks first to determine if a solute has segregated to an interface. We therefore consider the conditions required to operate the analytical microscope to maximize the detection sensitivity of interfacial segregants.The choice of lens operating conditions for carrying out interface analysis on a STEM is not necessarily intuitive. Apart from the geometrical optics, instrumental artifacts may adversely influence the observed SNR and SBR. We have carried out a series of EDX experiments to compare the working performance of interface analysis with that expected using a simple planar interface segregation model and geometrical optics.
Direct imaging of spatially varying potential and charge across internal interfaces in solids
Authors: Ravikumar V. , Rodrigues R. P. , Dravid V. P. 
Published: June 2020

The importance of spatially varying potential (and thus charge) across lattice discontinuities in solids has been recognized in many technologically important systems, especially those containing electrically active interfaces, e.g. electroceramics. The presence of spatially varying potential across electroceramic interfaces has been indirectly deduced and analyzed using predominantly bulk measurement techniques like I-V, C-V curves and impedance spectroscopy. Direct imaging of spatially varying electrostatic potential profile and determination of the sign, magnitude and spatial distribution of the associated interface- and space- charge (and therefore defect density) in electroceramics have remained elusive.We have utilized the technique of transmission high energy electron holography to directly image and quantify the electrostatic potential across grain boundaries (GBs) in SrTiO3, a functional electroceramic. The phase of the exit wave function at the GB region can be altered by : (i) variation in local mean inner potential (related to the change in density of atoms at the GB), (ii) differential diffraction conditions across the interface, (iii) change in the local specimen thickness and, (iv) presence of local electrostatic (electrical charge) and magnetic potential.
AFM studies of annealed single-crystal α-alumina surfaces
Authors: Heffelfinger Jason R. , Bench Michael W. , Barry Carter C. 
Published: June 2020

Since the invention of atomic-force microscopy (AFM) in 1986, the technique has found an invaluable niche in the imaging of insulating surfaces. AFM allows for analysis of topographical details at the atomic level with minimum sample preparation, but the technique is subject to artifacts such as broadening of surface structures and ghost images of the tip due to the finite size and shape of the contacting probe. In the present investigation, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used as supporting techniques to AFM in the study of annealed single-crystal α-alumina surfaces. Although discrepancies were found between the EM data and the AFM images which point to artifacts inherent to the AFM, useful information on surface step heights and roughness of terraces was gained using AFM.AFM studies were performed on a Nanoscope III (Digital Instruments, Santa Barbara, CA) using microfabricated Si3N4 cantilevers (Ultralevers, Park Inst., Sunnyvale, CA).
A correlation of CL emissions from Penrith sandstone with elemental distributions obtained by simultaneous SEM-CL and EDS analysis
Authors: Wright Paul J. 
Published: June 2020

Most industrial and academic geologists are familiar with the beautiful red and orange cathodoluminescence colours produced by carbonate minerals in an optical microscope with a cold cathode electron gun attached. The cement stratigraphies interpreted from colour photographs have been widely used to determine the post depositional processes which have modified sedimentary rock textures.However to study quartzose materials high electron densities and kV's are necessary to stimulate sufficient emission. A scanning electron microscope with an optical collection system and monochromator provides an adequate tool and gives the advantage of providing secondary and backscattered electron imaging as well as elemental analysis and distribution mapping via standard EDS/WDS facilities.It has been known that the incorporation of many elements modify the characteristics of the CL emissions from geological materials. They do this by taking up positions between the valence and conduction band thus providing sites to assist in the recombination of electron hole pairs.
Quantitative nano-characterization of heterogeneous catalysts
Authors: Crozier P.A. , Pan M. 
Published: June 2020

Heterogeneous catalysts can be of varying complexity ranging from single or double phase systems to complicated mixtures of metals and oxides with additives to help promote chemical reactions, extend the life of the catalysts, prevent poisoning etc. Although catalysis occurs on the surface of most systems, detailed descriptions of the microstructure and chemistry of catalysts can be helpful for developing an understanding of the mechanism by which a catalyst facilitates a reaction. Recent years have seen continued development and improvement of various TEM, STEM and AEM techniques for yielding information on the structure and chemistry of catalysts on the nanometer scale. Here we review some quantitative approaches to catalyst characterization that have resulted from new developments in instrumentation.HREM has been used to examine structural features of catalysts often by employing profile imaging techniques to study atomic details on the surface. Digital recording techniques employing slow-scan CCD cameras have facilitated the use of low-dose imaging in zeolite structure analysis and electron crystallography. Fig. la shows a low-dose image from SSZ-33 zeolite revealing the presence of a stacking fault.
EM of diamond-coated molybdenum field emission cathodes
Authors: Myers A. F. , Choi W. B. , McClure M. T. , Hren J. J. , Voelkl E. , Frost B. , Allard L. F. 
Published: June 2020

Molybdenum is a common metal used to fabricate field emission devices.1-2 However, during extended operation, Mo cathodes exhibit current instabilities, which are thought to arise from adsorption of contaminants on the emitter surface. Coating Mo field emitters with diamond may enhance the current stability, as well as the total emission current. An understanding of the diamond nucleation mechanism is crucial for depositing consistent, uniform coatings on the emitters, and therefore producing reliable devices. To the author's knowledge, little information exists about the mechanism of diamond nucleation on these highly curved Mo surfaces.In order to study the diamond nucleation mechanism, the morphology of the diamond coating and the structure of the diamond/Mo interface were analyzed by high resolution TEM. Emitters make excellent TEM specimens, since no further sample preparation is required after the diamond deposition; artifacts thus do not become an issue in interpreting the TEM results. Figure 1 shows that the films have a general morphology of clustered nanocrystalline particles.
Correlation of defect densities in semiconductors measured by TEM and optical profiling instruments
Authors: Mulestagno L. , Holzer J.C. , Hill D.E. , Fraundorf P. 
Published: June 2020

The measurement of oxygen precipitate defect densities in Czochralski (CZ) Silicon wafers after standard heat cycles, or at strategic points in the device manufacturing process is often used as a tool to understand the oxygen precipitation behavior of the wafers on which electronic devices will be manufactured and to measure variability in the precipitation . The relevance of these measurements arises from the fact that controlled oxygen precipitation in the bulk of the wafer is used as a means to ‘getter’ unwanted impurities from the device layer of the wafer, and control of oxygen precipitation can be an important factor in device yields.Typically the density of oxygen precipitate in a given wafer and the depth profile is determined by physically counting defects on cleaved slices after preferential etch to reveal the defects . This is a fairly time-consuming and a destructive test. However in the last few years a number of companies have developed computerized, non-destructive IR laser scattering instruments which rely on the fact that silicon is transparent to IR., and a precipitate (having a different refractive index from silicon ), will scatter some of the laser beam which can be detected.
Microstructural investigation of surface roughness in MBE-grown AlAs
Authors: Rajesh R. , Droopad R. , Kuo C. H. , Carpenter R. W. , Maracas G. N. 
Published: June 2020

Knowledge of material pseudodielectric functions at MBE growth temperatures is essential for achieving in-situ, real time growth control. This allows us to accurately monitor and control thicknesses of the layers during growth. Undesired effusion cell temperature fluctuations during growth can thus be compensated for in real-time by spectroscopic ellipsometry. The accuracy in determining pseudodielectric functions is increased if one does not require applying a structure model to correct for the presence of an unknown surface layer such as a native oxide. Performing these measurements in an MBE reactor on as-grown material gives us this advantage. Thus, a simple three phase model (vacuum/thin film/substrate) can be used to obtain thin film data without uncertainties arising from a surface oxide layer of unknown composition and temperature dependence.In this study, we obtain the pseudodielectric functions of MBE-grown AlAs from growth temperature (650°C) to room temperature (30°C). The profile of the wavelength-dependent function from the ellipsometry data indicated a rough surface after growth of 0.5 μm of AlAs at a substrate temperature of 600°C, which is typical for MBE-growth of GaAs.
Microstructures of ultra high molecular weight polyethylene by SEM
Authors: Wang H. C. , Sung C. , Hamilton J. 
Published: June 2020

Ultra high molecular weight polyethylene (UHMWPE) is widely used in many orthopedic applications because of its good mechanical properties and excellent biocompatability. Mechanical properties are related to its ultra-high molecular weight, but the presence of defects in morphology will cause a decrease in these properties. The aim of this study was to characterize the microstructure and microchemistry of so-called “fusion defects”, observed by optical transmission microscopy, using SEM along with EDXS analysis. The fractured surface of UHMWPE was also studied.Defects similar to those found in commercially prepared UHMWPE were detected in the hot-pressed and extruded samples prepared at U-Mass Lowell using GUR 412. They consist of holes or cavities and sometimes appear to be circular in shape and are composed of variously sized small holes. The size of the defects is around 100 μm in diameter which is similar to the particle size of the raw powders.
Characterization of corrosion scales in water distribution pipes using SEM and energy dispersive X-ray spectroscopy (EDS)
Authors: Shull J. L. , Kriven W. M. , McAnally A. S. 
Published: June 2020

A series of water treatment programs involving different combinations of chemical additives was evaluated with the aim of reducing the levels of lead and copper in the drinking water of several communities in South Carolina. Test coupons from 7 pilot systems and 3 municipal distribution systems involved in the study were analyzed using SEM and EDS in order to determine the structure and composition of the corrosion scales and other deposits which formed on the interior pipe surfaces.Sample coupons consisted of short segments of copper pipe, each of which was coated on one end with 50-50 wt.% lead-tin solder. Small (3 mm × 6 mm) pieces cut from both the soldered and unsoldered ends of the coupons were used as specimens for SEM surface analysis. Cross-sectional specimens were prepared by embedding small pieces in an acrylic resin and using an ultramicrotome to obtain high quality surfaces.Analysis of the coupon surfaces produced results that were consistent with the corresponding water quality analyses.
HREM structure analysis of Σ13 symmetrical boundaries in strontium titanate bicrystals
Authors: Bonevich J.E. , Xiao S.Q. , Dahmen U. 
Published: June 2020

Strontium titanate (STO) has found a myriad of technological applications, most notably as a substrate material for superconductors such as YBa2Cu3O7-δ (YBCO). One example is the growth of thin film YBCO devices whereby grain boundaries introduced in the films are used to create SQUID devices. The nature of the interfacial structure plays an important role in determining the behavior of these materials, e.g., their electrical properties. We have thus endeavored to investigate the atomic structure of grain boundaries in STO and to explore the structure implications on the properties of YBCO films.The Σ13 STO bicrystals with two symmetrically inclined boundary planes of (510) and (320) were produced by Shinkosha Ltd.(Japan); the bicrystals were rotated by 22.6°±0.5° about the common [001] zone axis. Cross-sectional TEM specimens were prepared in the usual manner and examined in the NCEM's Atomic Resolution Microscope operating at 800 kV. The HREM images were subsequently digitized for template matching (cross-correlation) analysis.
Trial production of γ-type energy filtering TEM
Authors: Taniguchi Y. , Nakazawa E. , Taya S. 
Published: June 2020

Imaging energy filters can add new information to electron microscopic images with respect to energy-axis, so-called electron spectroscopic imaging (ESI). Recently, many good results have been reported using this imaging technique. ESI also allows high-contrast observation of unstained biological samples, becoming a trend of the field of morphology. We manufactured a new type of energy filter as a trial production. This energy filter consists of two magnets, and we call γ-filter since the trajectory of electrons shows ‘γ’-shape inside the filter. We evaluated the new energyγ-filter TEM with the γ-filter.Figure 1 shows schematic view of the electron optics of the γ-type energy filter. For the determination of the electron-optics of the γ-type energy filter, we used the TRIO (Third Order Ion Optics) program which has been developed for the design of high resolution mass spectrometers. The TRIO takes the extended fringing fields (EFF) into consideration. EFF makes it difficult to design magnetic energy filters with magnetic sector fields.
X-ray Gabor holography
Authors: Lindaas Steve , Jacobsen Chris , Kalinovsky Alex , Howells Malcolm 
Published: June 2020

Soft x-ray microscopy offers an approach to transmission imaging of wet, micron-thick biological objects at a resolution superior to that of optical microscopes and with less specimen preparation/manipulation than electron microscopes. Gabor holography has unique characteristics which make it particularly well suited for certain investigations: it requires no prefocussing, it is compatible with flash x-ray sources, and it is able to use the whole footprint of multimode sources. Our method serves to refine this technique in anticipation of the development of suitable flash sources (such as x-ray lasers) and to develop cryo capabilities with which to reduce specimen damage. Our primary emphasis has been on biological imaging so we use x-rays in the water window (between the Oxygen-K and Carbon-K absorption edges) with which we record holograms in vacuum or in air.The hologram is recorded on a high resolution recording medium; our work employs the photoresist poly(methylmethacrylate) (PMMA). Following resist “development” (solvent etching), a surface relief pattern is produced which an atomic force microscope is aptly suited to image.
The influence of the objective lens current in low magnification electron holography
Authors: Frost B.G. , Joy D.C. , Völkl E. , Allard L.F. 
Published: June 2020

In order to align an electron microscope for low magnification holography we usually completely switch off the objective lens and image the sample by the first intermediate lens. In addition, to achieve a highly coherent electron beam we highly excite the condensor lens resulting in a divergent illumination of the sample and the intermediate lens. Now negatively biasing the fiber of a Möllenstedt type biprism placed between the first an second intermediate lenses of our Hitachi HF-2000 field emission electron microscope creates two virtual sources below the back focal plane of the first intermediate lens. These two sources are necessary to form off-axis holograms. Slightly exciting the objective lens and still imaging the sample by the first intermediate lens results in two major changes in our holograms.First: Due to an electron beam less divergent or even convergent illuminating the first intermediate lens when exciting the objective lens (compare Fig. 1 to Fig.2) the angle β at which object wave and reference wave are superimposed decreases.
Quanitative aspects of electron diffraction using electron holography
Authors: Völkl E. , Allard L.F. , Frost B. , Nolan T.A. 
Published: June 2020

Off-axis electron holography has the well known ability to preserve the complex image wave within the final, recorded image. This final image described by I(x,y) = I(r) contains contributions from the image intensity of the elastically scattered electrons IeI (r) = |A(r) exp (iΦ(r)) |, the contributions from the inelastically scattered electrons IineI (r), and the complex image wave Ψ = A(r) exp(iΦ(r)) as:(1) I(r) = IeI (r) + Iinel (r) + μ A(r) cos(2π Δk r + Φ(r))where the constant μ describes the contrast of the interference fringes which are related to the spatial coherence of the electron beam, and Φk is the resulting vector of the difference of the wavefront vectors of the two overlaping beams. Using a software package like HoloWorks, the complex image wave Ψ can be extracted.
Studies of dental samples by the low-loss electron method in the field emission SEM
Authors: Wells Oliver C. , Rishton Stephen A. , Bromage Tim 
Published: June 2020

A low-loss electron (LLE) detector has been installed with a redesigned specimen stage in a Hitachi S800 field-emission SEM (Fig. 1). This has been evaluated by comparing secondary electron (SE) and LLE images of abrasive striations known as “microwear” on an uncoated human incisor mounted at 45° to the beam (Fig. 2).Microwear features typically appear as long linear scratches or discrete pits in the range 0.2 μm to 2.0 μm in width. These reflect both the specific contacts that one tooth makes against another when chewing (jaw movements and tooth wearing patterns) and the food eaten (seed, plant fiber, fruit, etc.). The density of scratches per unit area has been widely used as a measure of the dietary proclivities of an organism. Thus grazers have been distinguished from browsers on the basis of the greater density of scratches caused by opaline phytoliths in grasses that are harder than tooth enamel.
Improved 3-D reconstruction using stereo computer graphics and multiple tilt EM images
Authors: Peachey Lee D. , Fodor Lou , Haselgrove John C. , Dunn Stanley M. , Huang Junqing 
Published: June 2020

Stereo pairs of electron microscope images provide valuable visual impressions of the three-dimensional nature of specimens, including biological objects. Beyond this one seeks quantitatively accurate models and measurements of the three dimensional positions and sizes of structures in the specimen. In our laboratory, we have sought to combine high resolution video cameras with high performance computer graphics systems to improve both the ease of building 3D reconstructions and the accuracy of 3D measurements, by using multiple tilt images of the same specimen tilted over a wider range of angles than can be viewed stereoscopically. Ultimately we also wish to automate the reconstruction and measurement process, and have initiated work in that direction.Figure 1 is a stereo pair of 400 kV images from a 1 micrometer thick transverse section of frog skeletal muscle stained with the Golgi stain. This stain selectively increases the density of the transverse tubular network in these muscle cells, and it is this network that we reconstruct in this example.