bluuebunny/crossref_metadata_2025_split huggingface dataset:
TEM Study of bonded silicon wafers
Authors: Mulestagno L. , Craven R. , Fraundorf P. 
Published: June 2020

The promise of higher speed, radiation hard, high temperature capabilities, and increased device density has made SOI ( silicon - on - insulator) an attractive proposition since its conception several years ago . Until recently the methods for its manufacture had been plagued by low yields, and poor quality . Remarkable advances have been made lately resulting in increasing quantities of SOI wafers being sold commercially.The two main techniques for making SOI are Separation by Implantation of Oxygen (SIMOX) and direct wafer bonding (Bonded wafers). Little analytical work has yet been performed on the latter by the microscopy community at large, so we studied 2 commercial quality wafers with the intent of looking for particulate defects which might arise during annealing, and studying the oxide layer and oxide-SOI interface quality.Plane view samples were made from the SOI taking advantage of its chemistry, by dimpling and milling from the back-side, and then dipping in HF which attacks the oxide, and leaves large areas of silicon film suitable for TEM untouched.
Cathodoluminescence studies of materials for use in optical display devices
Authors: Wright P.J. 
Published: June 2020

Cathodoluminescence studies have been carried out for many years for the assessment of semiconductor materials such as Gallium Arsenide, Gallium Phosphide and Silicon. These investigations have relied on utilising the focused electron beam of an SEM to excite luminescence. This is subsequently directed through a monochromator to allow spectroscopy and also the acquisition of high resolution images showing the spatial distribution of the optically active centres (≥0.5μm).The recent growth of research in the production and characterisation of optically active materials and devices such as 3/5 or 2/6 LED's for the use in visible display products has fuelled the use of CL to determine the optical properties on a scale that is superior to that available by PL. In addition characterisation of the optical properties as a function of electron beam characteristics, dosage and at temperatures between 4.2K and 300K are possible.Results from GaN epilayers will be shown that indicate that two separate phases (alpha and beta) can be identified by the position of the Bound Exiton luminescence and that this luminescence is distributed randomly through the sample. The sites responsible for this luminescence are less than 0.5μm in size.
Multitechnique characterization of polysulfone gas permeation membranes
Authors: Behrens M. A. , Jois Y. H. R. , Dahlstrom P. L. 
Published: June 2020

Integrally thin skinned asymmetric polysulfone membranes developed for gas separation applications were prepared by casting a dope solution on a glass plate. A dry/wet phase inversion process with a forced convective evaporation step is then used to form a skin. The membrane is immersed in water before undergoing a solvent exchange and drying process. The thin skin of these membranes allows gas to selectively diffuse through the membrane when the surface is without defects. The gas transport properties (selectivity and flux) are measured using standard techniques and are reported on Table II.Scanning electron microscopy is an important method of examining the cross-sections and surfaces of these membranes to determine the surface integrity, skin thickness, and porosity of the supporting substructure. The ideal integrally thin skin thickness is 1000 Å or less. We further characterized these membranes using Atomic Force Microscopy to image the membrane surface and X-ray Photoelectron Spectroscopy to obtain chemical information about the polysulfone surface.
Parallel EELS of polymers in a TEM: energy calibration of the carbon-K-edge
Authors: Heckmann W. 
Published: June 2020

Electron energy loss spectroscopy (EELS) measures the loss in energy of the primary electrons caused by inelastic scatter at the electron shell. The energy loss can be detected with magnetic spectrometers operating in parallel (PEELS) and with imaging magnetic/electrostatic Castaing or magnetic omega filters. To detect EEL-spectra of radiation sensitive polymers a PEEL-spectrometer is useful, because it allows a very fast detection of the spectrum. Dynamic measurements that show the changes in the PEEL spectra during irradiation, yield additional information.An important part of recording the spectrum at high energy resolution is the energy calibration. In parallel detection, the spectrum is displayed on a diode array with a finite number of diodes (1,024). So at high energy resolution (0.05 eV/ch) it is in general only possible to observe a narrow section of about 50 eV of the total spectrum. At higher energy losses that do not allow simultaneous measurement of the elastic peak, it is only possible to give a very approximate value in terms of eV units as the primary radiation energy can drift during the measurement. It is therefore impossible to compare spectra with one another as the absolute energy scale is not known. But, as the chemical shifts of interest have an order of magnitude ranging from fractions of an eV to several eV, it is essential to know the absolute energy scale.
Thin foil preparation for AEM study of small metal particles in stony meteorites
Authors: Yang Cheol-Woong , Williams David B. , Goldstein Joseph I. 
Published: June 2020

The phase transformation processes and phase equilibria of the Fe-Ni and Fe-Ni-S system at low temperature can be better understood by characterizing the microstructure and chemistry of metallic particles in stony meteorites using analytical electron microscopy (AEM) techniques. However stony meteorites have a composite nature consisting of metal particles embedded in an inherently brittle silicate matrix, which causes a differential thinning rate. The thin foil preparation of the metal particles for AEM has proved to be very difficult, and we report on the first successful specimen preparation.Materials of this type present particular difficulties in the preparation of thin foil specimens because the area of interest is limited to specific regions within the metal particles. The metal particles are usually less than 500 μm in size and the silicate matrix is inherently brittle. Moreover, the interfaces between metal particles and silicates are weak because of corrosion, depending on cooling, etc.
Quantitative defect studies in semiconductor TEM samples prepared by low angle ion milling
Authors: Mulestagno L. , Holzer J.C. , Fraundorf P. 
Published: June 2020

Due to the wealth of information, both analytical and structural that can be obtained from it TEM always has been a favorite tool for the analysis of process-induced defects in semiconductor wafers. The only major disadvantage has always been, that the volume under study in the TEM is relatively small, making it difficult to locate low density defects, and sample preparation is a somewhat lengthy procedure. This problem has been somewhat alleviated by the availability of efficient low angle milling.Using a PIPS® variable angle ion -mill, manufactured by Gatan, we have been consistently obtaining planar specimens with a high quality thin area in excess of 5 × 104 μm2 in about half an hour (milling time), which has made it possible to locate defects at lower densities, or, for defects of relatively high density, obtain information which is statistically more significant (table 1).
High-resolution EM study of submicrometer-grained Al-Mg solid solution alloys
Authors: Horita Z. , Smith D. J. , Furukawa M. , Nemoto M. , Valiev R. Z. , Langdon T. G. 
Published: June 2020

It is possible to produce metallic materials with submicrometer-grained (SMG) structures by imposing an intense plastic strain under quasi-hydrostatic pressure. Studies using conventional transmission electron microscopy (CTEM) showed that many grain boundaries in the SMG structures appeared diffuse in nature with poorly defined transition zones between individual grains. The implication of the CTEM observations is that the grain boundaries of the SMG structures are in a high energy state, having non-equilibrium character. It is anticipated that high-resolution electron microscopy (HREM) will serve to reveal a precise nature of the grain boundary structure in SMG materials. A recent study on nanocrystalline Ni and Ni3Al showed lattice distortion and dilatations in the vicinity of the grain boundaries. In this study, HREM observations are undertaken to examine the atomic structure of grain boundaries in an SMG Al-based Al-Mg alloy.An Al-3%Mg solid solution alloy was subjected to torsion straining to produce an equiaxed grain structure with an average grain size of ~0.09 μm.
Microstructure of roughened surface in metal rolling
Authors: Lee W. M. , Meshii M. , Wilson W. R. D. , Chiou W. A. , Lin C. S. 
Published: June 2020

Flat rolled aluminum products have a $25 billion market worldwide annually. The topography of the rolled surface is a key measure of surface quality. A dull surface finish can be generated by non-homogeneous surface deformation when the sheet is rolled under conditions of hydrodynamic lubrication. This is undesirable for some applications where high reflectivity is required, though it improves paintability. Wilson and Schmid have investigated the influence of lubrication conditions on roughening. Although the texture evolution during the hot and cold rolling of aluminum has been studied, the basic mechanisms of the roughening process are not fully understood. The purpose of the present research is to explore the microstructural changes associated with the evolution of surface roughness and to use this information to develop mathematical models which can accurstely describe the surface roughening evolution process.A TEM study of cross-sectional microstructure evolution of aluminum alloy Al 5052-0 material during cold rolling in the presents of a thick lubricant film has been conducted. Commercial aluminum alloy AL 5052-0 as-received was used in the experiments.
Microanalysis and characterization of protective coatings used in metal-matrix composites
Authors: Heffelfinger Jason R. , Kieschke Robert R. , Barry Carter C. 
Published: June 2020

Transmission electron microscopy (TEM), scanning electron microscopy (SEM) and parallel-aquistion electron-energy loss spectrometry (PEELS) have been used to investigate various coating schemes used in alumina-fiber reinforced titanium alloys. The high-temperature properties of metal-matrix composites (MMC's) depend greatly on the interface between the ceramic fiber and metal matrix. The chemical and mechanical properties of this interface may be tailored by coating the alumina fibers with various materials. In this work, emphasis has been placed on the chemical aspect of the coatings and their role in inhibiting the reaction between the alumina fiber and the titanium matrix. The brittle nature of the reaction products, Ti3Al and TiAl, weakens the composite and thus leads to its ultimate failure.The composites are made of α-alumina fibers (Nextel 610 with a mean diameter of ~12 mm) which are first coated with thin protective layers such as Y2O3 and Nb followed by a coating of β-titanium alloy (TIMETAL 21S Ti -15Mo -3A1 -2Nb -0.2Si.) Several thousand fibers are then placed together inside a glass tube and HIP-ped (Hot Isostatic Press) at temperatures of ~900°C and times of ~2 hours to attain a dense composite.
Microstructure of plasma-deposited iron-nitride films
Authors: Siriwardane H. , Polly C. , Sago A. , Fraundorf P. , Pringle O.A. , Newkirk J. W. , James W.J. 
Published: June 2020

Iron nitride films are potential candidates for information storage media. In order to use the films as a perpendicular magnetic recording media, it is necessary to know about the micro-, crystal, and magnetic structures, physical properties, and processing of these thin films. Here we describe the micro- structure of plasma-deposited iron nitride films.The microstructure of films deposited on glass and carbon support films on copper grids were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Auger electron Spectroscopy (AES). According to XRD, single phase Fe3N was successfully produced on glass substrates at temperatures 200, 275, 400, & 500 °C, and flow ratios between 0.4 to 15.3 of Fe(CO)5, and NH3. Electron diffraction peak positions of films were compared with Fe3C, Fe7C3, Fe2N, Fe3Nγ-Fe4N, Fe5N2 and Fe3O4 crystal structure d-spacings. The presence of a carbide satellite peak in AES data and by matching all d-spacings in the JCPDS Fe3C card file with every experimental diffraction pattem, enabled us to confirm the presence of Fe3C in these films at all deposition temperatures.
Size distribution standards measured by digital SEM imaging
Authors: Kelly James F. 
Published: June 2020

The National Institute of Standards and Technology (NIST) certifies several size and size distribution Standard Reference Materials (SRMs) using spherical particles ranging in diameter from submicron to several millimeters. Glass beads are used as SRMs for a variety of laboratory applications. Their broad size distribution and spherical shape make them a model material for calibration of instruments for powder measurements.The glass bead standard (SRM1017b) covering the diameter range from 50μm to 350μm is currently being certified using SEM backscatter electron imaging. The digital images are acquired using an AMRAY SEM connected to a Apple Power Macintosh via a 4pi digital interface. The public domain computer program, NIH Image, is used in the image acquisition and size analysis. Figure 1 shows the spherical nature of the glass beads. Measurement of the circular area of each particle permits the calculation of the particle volume and diameter. The system magnification in terms of pixels per micrometer using an optical stage micrometer calibrated at NIST by laser interferometry.
A security circuit for the image intensifier on the Electron Microscope
Authors: Shih Min-Yi , Hsu Tung 
Published: June 2020

Image intensifiers are widely used on the electron microscopes, mostly for observation and recording of weak images. Usually, the image intensifier is not used in diffraction mode, for the strong direct beam may damage the YAG crystal. However, neither the microscope nor the image intensifier is equipped with any protection mechanism, leaving the safety of the intensifier as the responsibility of the operator.While modifying a JEOL JEM-100C microscope for UHV-REM, we designed a security circuit to blank the electron beam in order not to damage the image intensifier accidentally. The required logic, shown in Fig. 1, indicates the electron beam blanked (1) or unblanked (0) under all possible combinations of three parameters. The requirement is that the beam must be blanked (1) while the view screen is fully raised (1), film not advanced (0), and the SAD button is depressed (1). Blanking is accomplished with a 5V signal applied to a relay and short the deflection coil. The circuit is shown in Fig. 2.
Exploring local properties of biological surfaces with the Atomic Force Microscope
Authors: Hoh Jan H. 
Published: June 2020

The atomic force microscope (AFM) is developing into a very general tool for exploring biological surfaces. At present there are four broad areas of applications for the AFM: imaging surfaces, manipulating surfaces, measuring intermolecular forces and determining micromechanical properties. Because the dimensions of the apex of the tip used are typically on the order of 10's of nanometers, local measurements of properties are possible on a much smaller length scale than previously. Several reviews that provide further details on AFM instrumentation and biological applications have been published. These reviews also provide specific references for the range of applications that will be reviewed in this tutorial.AFM imaging modes can be divided into two groups based on the detection method, the DC method detects the absolute deflections of a cantilever while the AC method detects the RMS amplitude of an oscillating cantilever. Conventional contact AFM, sometimes called repulsive mode, is based on DC detection of the cantilever movement as the tip moves across a surface, usually in direct contact with the surface. The deflection of the cantilever is used to control the height of the sample, and the force applied to the sample, through a feedback loop.
Image processing and analysis fundamentals for microscopy
Authors: Newell Bruce D. 
Published: June 2020

Advances in computers and related digital hardware, coupled with sophisticated software techniques have resulted in microscopy migrating from its historical roots as a subjective, qualitative science towards a more robust position as a truly quantitative technique. Granted, we will probably never totally remove the microscopist from the process of image interpretation (at least those at this conference hope not) but we will certainly continue to progress from describing our image data in qualitative terms (e.g., many/few, large/small, equiaxis/elongated, ordered/random, rough/smooth) to quantitative measurements of number, size, shape, location, texture, and so on.To move along the path toward quantitative image interpretations requires an understanding of image processing and analysis (IP/A) fundamentals to insure that the data obtained is of the required accuracy and precision. A generalized model of the critical steps in the image processing and analysis chain is given in Figure 1. This tutorial will examine the fundamental issues in each step that impact the quality of the final result and provide a broad overview of techniques that may be applicable.
Correlative microscopy in distrubuted (client/server) computing environments: tools for catalyzing the rapid dissemination of information about the cell biology of the human prostate
Authors: Hakam A. , Gau J.T. , Grove M.L. , Evans B.A. , Shuman M. , Strom S.C. , Bahnson R. , Sethi P.K. , Song K.C. , DiGiorgio C.J. , He F. , Hatton C.S. , Wimberly F.C. , Roskies R.Z. , Deckenbaugh L. , Gross W. , Schubert E. , Becich M.J. 
Published: June 2020

Prostate adenocarcinoma is the most common malignant tumor of men in the United States and is the third leading cause of death in men. Despite attempts at early detection, there will be 244,000 new cases and 44,000 deaths from the disease in the United States in 1995. Therapeutic progress against this disease is hindered by an incomplete understanding of prostate epithelial cell biology, the availability of human tissues for in vitro experimentation, slow dissemination of information between prostate cancer research teams and the increasing pressure to “ stretch” research dollars at the same time staff reductions are occurring.To meet these challenges, we have used the correlative microscopy (CM) and client/server (C/S) computing to increase productivity while decreasing costs. Critical elements of our program are as follows:1) Establishing the Western Pennsylvania Genitourinary (GU) Tissue Bank which includes >100 prostates from patients with prostate adenocarcinoma as well as >20 normal prostates from transplant organ donors.
Nucleoskeltal proteins with bifunctional roles in the nucleus and mitotic apparatus: a paradigm for protein dynamics in the cell cycle
Authors: Brinkley B. R. , He D. , Zeng C. , Scott B. , Turner D. 
Published: June 2020

The eukaryotic cell nucleus, once believed to contain structureless nucleoplasm surrounding chromatin and the nucleolus is now thought to contain an extensive nucleoskeletal matrix on which chromatin, RNP and a complex array of transcription factors, hormone receptors and other regulatory factors are spatially arranged. A distinct nucleoskeleton has been difficult to identify in the intact nucleus, due in part to masking by a dense array of chromatin fibers. However, if chromatin is extracted by nuclease digestion and high salt, an underlying anastomosing network of 9-13 nm core filaments can be demonstrated. The nucleoskeleton resembles the cytoplasmic intermediate filament complex but is confined entirely within the nucleus where it connects the nuclear lamina with various nuclear organelles, forming an integral lattice of fibers collectively called the nuclear matrix. Although the molecular composition of the nucleoskeleton remains elusive, its integrity apparently requires RNP and a growing list of nuclear matrix proteins.Although relatively insoluble within the nuclear compartment, the entire nucleoskeletal framework and associated chromatin is efficiently dismantled, packaged, partitioned and reassembled into daughter nuclei during mitosis.
Growth cone dynamics of embryonic grasshopper pioneer neurons in situ
Authors: O'Connor Tim P. 
Published: June 2020

During development of the nervous system, neurons extend axons over relatively long distances to contact their targets. A variety of molecules in the extracellular environment are instrumental in guiding a neuronal process. The motile tip of the process, the growth cone, senses and transduces this guidance information, resulting in a local reorganization and consolidation of the cytoskeleton. Although much work has been dedicated to isolating the molecules that guide a neuronal growth cone, relatively little is known about the dynamic processes that occur when a growth cone turns in response to guidance information. Recently, a number of biological systems have been developed that enable time lapse imaging of growth cones as they extend axons in situ. One of these systems is the embryonic grasshopper limb fillet.In the grasshopper embryo, a pair of sibling neurons, named the Til pioneers, are the first neurons to extend axons toward the central nervous system (CNS).
Optical imaging of brain slice preparations using voltage sensitive dyes
Authors: Nelson D.A. , Katz L.C. 
Published: June 2020

Fast responding, biological membrane-soluble voltage sensitive dyes are probes which make it possible to directly monitor the electrical activity of neuronal tissues with both high temporal and high spatial resolution. High temporal resolution is desirable because of the millisecond time scale on which neuronal events occur. High spatial resolution is desirable to better reveal the complex interactions between different regions of neural circuits.Taking full advantage of the promise of voltage sensitive dyes can be both difficult and expensive. Tissues stained with these dyes undergo very small (often less than one part in a thousand) relative changes in fluorescence in response to changes in transmembrane potential. The signal-to-noise ratio is similarly small for these responses. Finally, the responses are very fast. Most major components of the signal rise to their maximum and then disappear within 15 milliseconds of stimulation (figure 1).Because standard video cameras are inadequate for recording the very small and very fast optical signals transduced by voltage sensitive dyes, specialized detection equipment is required. This entails a high cost per pixel, often limiting the practial number of detector elements to a few hundred or even less.