bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sharpening of EELS data by deconvolution
Authors: Batson P.E. 
Published: June 2020

The IBM Wien filter spectrometer now delivers 0.1eV resolution with a diode array detector. Figure 1 shows the zero-loss distribution, Z(E), in the IIB501 STEM. Figure 2 shows the Al L2,3 edge obtained at the same time. This report covers a successful application of a suggestion by D. W. Johnson that deconvolution may be possible if Z(E) contains a sharp edge, such as that on the left in Figure 1.In principle, deconvolution can be done by a simple division of the fourier components of the data D(ω) by Z(ω). In practice, severe amplification of noise results by the naive approach. In this work, I use a modified Wiener filter algorithm:(1)
Improved detection limits with parallel-detection EELS
Authors: Krivanek O.L. , Kundmann M.K. 
Published: June 2020

Parallel-detection electron energy-loss spectrometers (PEELS) have improved the detection limits of electron energy-loss spectroscopy (EELS) so much that established comparisons between EELS and energy-dispersive X-ray spectroscopy (EDXS) no longer apply. We have therefore decided to reinvestigate the comparative advantages of EELS as a microanalytical technique.Two types of detection limits are of interest: minimum detectable mass (MDM), and minimum detectable mass fraction (MMF). MDM has been improved by parallel-detection EELS so much that single atoms of elements with favorable cross-sections have become detectable. Since detecting a single atom requires a probe with at least 0.1 nA of current and a diameter of no more than 1 nm, this level of performance needs an electron microscope equipped with an efficient field-emission gun (FEG). On the other hand, because the ratio of the signal from a uniformly dispersed element to the signal from the matrix does not depend on the size of the probed area, MMF depends on the total available probe current rather than the probe current density. This means that MMF should be better for microscopes equipped with thermionic guns than for ones equipped with FEGs.
Microstructures and recording performances of longitudinal media using different atomic mass underlayer materials
Authors: Nguyen Thao A. , Yogi Tadashi , Lambert Steven 
Published: June 2020

Magnetic and recording properties of Co-based longitudinal media are strongly influenced by the underlayer and sputtering conditions. We have investigated the relationship between magnetics, recording noise and microstructural characteristics of CoPtCr media on Mo and W underlayers over a sputtering pressure range 3-24 mtorr. complementing our earlier work of Cr underlayer.The media structure is C/CoPtCr/Mo or W, with thicknesses of 25/25/100 nm respectively. The film structure was sputter-deposited in a DC S-gun magnetron system. The remanence-thickness product, Mft, was kept in the range of 0.6-1.0 10-3 emu/cm2. The films were characterized by a vibrating sample magnetometer for their magnetic properties. Magnetic recording measurements were made with thin film inductive write heads with a track width of about 10 μm at a flying height of about 5 μm. The microstructures were studied using the IEOL JEM 4000 FX and AKASFII 002-B transmission electron microscopes.
Texturescope: An automatic TEM technique for the imaging of preferred orientations
Authors: Weiland H. 
Published: June 2020

The distribution of crystallographic orientations, the texture, is one of the basic structural parameters. Knowledge of the texture on a very local scale is necessary to study aspects of processes such as recrystallization and deformation. With an electron microscope, the texture can be determined1 either by measuring the orientations of individual grains or by measuring local pole figures and obtaining in this way the orientation distribution of hundreds of grains. The latter method, however, does not preserve the spatial distribution of the orientations.The measurement of pole figures in the TEM is based on the same principles used for conventional pole figure determination by X-rays in transmission. The electron microscope has the additional capability that the area of interest can be imaged. For the measurement of local pole figures, the intensity distribution along a selected hkl-diffraction ring is measured, while the specimen is tilted around a specified axis over a large range (e.g. sheet products are usually tilted around the rolling direction). The measured diffracted intensities must be corrected for absorption of the primary and diffracted beams as well as for the change in diffracting volume. Using selected area diffraction, pole figures of specimen areas between 300 μm and 1 μm in diameter can be analyzed quantitatively.
Microscopy of VLSI oxides
Authors: Iwasaki Hiroshi 
Published: June 2020

The oxide of silicon and other insulating films form an integral part of every VLSI circuit (e.g. Fig. 1). Thin gate oxide(SiO2) in the thickness range of 10-20 nm (5-10 nm) is needed for submicron (quatermicron) devices. For such devices, characterization of surface roughness at Si/SiO2 interfaces becomes increasingly important because it is expected to affect field-dependent dielectric breakdown (FDDB), time-dependent dielectric breakdown (TDDB) and carrier mobility of MOS FETs more sensitively at necessitated higher operating electric fields. The Si/SiO2 interface is usually considered as the boundary between Si lattice image and granular SiO2 image.P-type, CZ- Si(001) substrates with resistivity of 10-13 Ωcm were first cleaned by the RCA method and were oxidized in aquartz tube to 16nm thickness: OC2=100% at 900°C for 53 min (dry oxide), O2/H2=1/4 for 11 min (wet oxide). Some MOS structured samples were also studied. Some dry oxide and reoxidized nitrided oxide (ONO) of 7nm thickness were formed by rapid thermal process for electron mobility study.
A superior cathodoluminescence spectral analysis and imaging system for semiconductor characterisation
Authors: Wright P J 
Published: June 2020

Cathodoluminescence is a useful technique in the structural and electro optical characterisation of semiconductors. When performed in a electron microscope, both high spatial resolution images and spectra may be obtained by use of the correct equipment.Many designs for instruments suitable for cathodoluminescence spectral analysis and imaging in electron microscopes have been described in the literature during the past 25 years. These have often exhibited improved performance when compared with commercially available systems. The prime reason for this has been the willingness of the dedicated CL researcher to mount large, heavy monochromators directly to the chamber of their microscope. The result has been a microscope committed to CL analysis. However, many potential CL users have to use shared facilities and may not compromise the performance or appearance of the microscope. Subsequently, many CL systems have had the monochromator decoupled from the CL collection optics by either fibre optic bundles or quartz fibres. This has allowed the monochromator and its associated detectors to be easily decoupled from the SEM when not in use. Considerable transmission losses have been incurred and in many cases, it has been necessary to duplicate detectors to allow both spectral analysis and imaging. This has resulted in instruments which were less than optimum in both efficiency and operation.
Electron microscopy of GaAs grown on Si- and Ge-based substrates
Authors: Malta D.P. , Posthill J.B. , Timmons M.L. , Sharps P.R. , Venkatasubramanian R. , Markunas R.J. 
Published: June 2020

A GaAs-on-Si technology is desirable to take advantage of the mobility and direct bandgap of GaAs in combination with the crystalline quality, low cost and established technology of Si. Differences in lattice constant (4.1%), thermal expansion coefficient (a factor of ~ 3), and bonding polarity between the two materials can lead to problems such as: threading dislocation formation, thermally induced stress and delamination, and antiphase domain boundaries (APBs), respectively. The lattice mismatch is responsible for the formation of (necessary) misfit dislocations which can concurrently create threading dislocations with typical densities in the range of 106 - 108cm-2. This density of electrically active defects in a device region is highly undesirable.A proposed scheme for lattice mismatch accommodation and potential threading dislocation reduction has previously been reported in which each layer of a SixGe1-x multilayer structure (MLS) is grown beyond the critical thickness with a progressively higher Ge composition than the previous layer.
Phase segregation in GaAs layers grown at low temperature
Authors: Liliental Zuzanna , Kilaas Roar 
Published: June 2020

GaAs device and circuit performance may be impaired by substrate conduction. One such effect, called sidegating, leads to undesirable cross-talk between neighboring devices. This problem can be avoided by isolating the active device layer from the substrate with a GaAs buffer layer grown by molecular beam epitaxy (MBE) at low temperatures (LT GaAs). The LT GaAs layers show high resistivity, a large trap density, and breakdown strengths about ten times that of semi-insulating GaAs. These layers are grown at a substrate temperature of ~ 200°C. A large (~1 at.%) excess of As in these as-grown layers causes an increase (~0.1%) in the GaAs lattice parameter.The crystal structure of these layers is very sensitive to the growth parameters such as: growth temperature, As/Ga flux ratio and growth rate. With decreasing growth temperature a higher As concentration can be incorporated and only a smaller layer thickness of high crystal perfection can be grown.
Analysis of 2D and 3D defects associated with precipitation of Cu in silicon
Authors: Rice P.M. , Kim MJ. , Carpenter R.W. 
Published: June 2020

Extrinsic gettering of Cu on near-surface dislocations in Si has been the topic of recent investigation. It was shown that the Cu precipitated hetergeneously on dislocations as Cu silicide along with voids, and also with a secondary planar precipitate of unknown composition. Here we report the results of investigations of the sense of the strain fields about the large (~100 nm) silicide precipitates, and further analysis of the small (~10-20 nm) planar precipitates.Numerous dark field images were analyzed in accordance with Ashby and Brown's criteria for determining the sense of the strain fields about precipitates. While the situation is complicated by the presence of dislocations and secondary precipitates, micrographs like those shown in Fig. 1(a) and 1(b) tend to show anomalously wide strain fields with the dark side on the side of negative g, indicating the strain fields about the silicide precipitates are vacancy in nature. This is in conflict with information reported on the η'' phase (the Cu silicide phase presumed to precipitate within the bulk) whose interstitial strain field is considered responsible for the interstitial Si atoms which cause the bounding dislocation to expand during star colony growth.
TEM evaluation of graded SixGe1-x heterolayers
Authors: David Theodore N. , Tomozane Mamoru , Liaw Ming 
Published: June 2020

There is extensive interest in SiGe for use in heterojunction bipolar transistors. SiGe/Si superlattices are also of interest because of their potential for use in infrared detectors and field-effect transistors. The processing required for these materials is quite compatible with existing silicon technology. However, before SiGe can be used extensively for devices, there is a need to understand and then control the origin and behavior of defects in the materials. The present study was aimed at investigating the structural quality of, and the behavior of defects in, graded SiGe layers grown by chemical vapor deposition (CVD).The structures investigated in this study consisted of Si1-xGex[x=0.16]/Si1-xGex[x= 0.14, 0.13, 0.12, 0.10, 0.09, 0.07, 0.05, 0.04, 0.005, 0]/epi-Si/substrate heterolayers grown by CVD. The Si1-xGex layers were isochronally grown [t = 0.4 minutes per layer], with gas-flow rates being adjusted to control composition. Cross-section TEM specimens were prepared in the 110 geometry. These were then analyzed using two-beam bright-field, dark-field and weak-beam images. A JEOL JEM 200CX transmission electron microscope was used, operating at 200 kV.
Advantages of Koehler illumination for selected area diffraction
Authors: Benner G. , Bihr J. , Weimer E. 
Published: June 2020

The advantages of Koehler illumination for imaging are well known. This new mode of illumination in the Transmission Electron Microscope (TEM), however, provides advantageous results for all modes of operation of a TEM, in particular for Selected Area (SA) diffraction.In a conventional TEM, the last condenser lens is strongly excited (coherent illumination) to obtain selected area diffraction. The size of the diffraction spots is determined by the demagnified image of the electron source (cross-over) in the back focal plane of the objective lens. Since a large area of the specimen is illuminated, the diffracting area must be limited in the intermediate image plane by the selected area aperture (Fig. 1a).Due to the spherical aberration of the objective lens, the higher orders of the diffraction pattern of the axial points are eliminated by the selected area apertures and are thus lost in the photograph of the diffraction pattern (dashed rays in Fig. 2).
Orientation of poly(3-alkylthiophene) on polyethylene crystals
Authors: Ihn K.J. , Moulton J. , Smith P. 
Published: June 2020

Poly(3-alkylthiophene)s (P3ATs) are conductive polymers soluble in many organic solvents. The number of carbon atoms (n) in the linear side chain in P3ATs used in this study was 6, 8, and 12. We concentrate on the result of P3HT (n=6), since similar results were obtained for the other two cases. In this paper we will report the molecular packing in P3HT whisker, and also the morphology and orientation of P3HT epitaxial growth on polyethylene (PE) crystals.P3HT whiskers were grown from a dilute solution of cyclohexanone while cooling the solution to room temperature. The color of the solution changed to red from yellow as the whiskers were formed. P3HT whiskers were also grown in cyclohexanone solution on PE single crystals mounted on a Cu grid supported by carbon film. Ultra-high molecular weight (UHMW) PE (Mw=4x106) gel film was uniaxially stretched (draw ratio=100). The drawn gel film was dipped into a xylene solution of P3HT at room temperature in order to crystallize the P3HT molecules onto the PE crystal. The samples were examined by a transmission electron microscope (TEM) at 80 kV.
(001) grain boundaries in Ag-clad Bi2Sr2Ca1Cu2O8+y (BSCCO) tapes
Authors: Feng Y. 
Published: June 2020

Recently, Ag-clad tapes of Bi-cuprate superconductors have shown great promise for application as conductors in very high magnetic fields at temperature 4-20 K. High critical current densities (Jc) with weak field dependence indicate that the powder-in-tube process can drastically reduce the effect of grain boundary weak links at 4-20 K. It is thus of great interest to study the grain boundaries in the Ag-clad BSCCO tapes to understand their effect on the Jc.BSCCO Ag-clad wires with 2:2:1:2 starting composition were drawn and rolled to rectangular tapes (0.1 x 3 mm) with BSCCO core thickness of 45μm. The sample was heated at 920°C for 15 minutes, cooled to 840°C at 10°C/h, then annealed at 840°C for 70 h. The measured Jc values exceed 2x104 A/cm2 (5T, 4.2K) and do not exhibit obvious weak link behaviour. In order to investigate the (001) grain boundaries, samples were made by bonding several tapes together along their broad face. Thin longitudinal slices were cut and then ion milled at 4.5 kV in liquid nitrogen. TEM was carried out by using a JEOL 200CX-II at 200 kV.
A TEM study of the effect of silver additions on residual superconductivity in shock-loaded Y-Ba-Cu-O
Authors: Birudavolu R. , Advani A.H. , Murr L.E. 
Published: June 2020

Although it has been demonstrated that metal additions to superconducting oxides can have a dramatic effect on superconductivity (as evidenced by variations in the resistancetemperature (R-T) signature), it is unclear where the metal additions go in the structure and what mechanism or mechanisms control the observed variations in superconductivity.Recent observations of explosively fabricated bulk YBa2Cu3O7 superconductors and sintered, shock-loaded YBa2Cu3O7 have indicated systematic degradation in the R-T signatures following shock-wave loading which increases with increasing peak shock pressure. However, silver additions to the Y-Ba-Cu-0 are observed to decrease this degradation. As illustrated in Fig. 1, the normal-state resistance becomes more metallic and the superconducting transition width decreases with increasing silver additions to sintered Y-Ba-Cu-O following shock loading at 3GPa peak pressure in a gas gun.
Techniques in preparing TEM specimens of mechanical alloyed fine powders
Authors: Chiou W. A. , Ramanathan R. , Stux A. , Lin Y. , Meshii M. 
Published: June 2020

The discovery of solid state processing of nanocrystalline and amorphous metals is considered to be a formation of a vital technology because of the potential in applications of these materials. Among the processes which are suitable tailoring advanced materials, mechanical alloying techniques are of special interest since they offer the most flexibility in mixing the constituent elements. To understand structural transformation from crystalline to amorphous states during mechanical alloying, the microstructural information from TEM is essential. This paper presents three different techniques used in preparing mechanically alloyed powder specimens for TEM study.Samples of commercially produced fine-grained (325 mesh) Cu (99.3%) and Zr (99%) powders were weighed to an atomic ratio of 1:1 as starting materials. These powders were mixed together in a steel vial and ball-milled in a SPEX mixer/mill machine. Samples were taken out after 11 hours of mixing when X-ray patterns showed that some amorphization had occurred. To examine the microstructure of these fine powders, three techniques were employed: (1) the suspension of powder particles on holey carbon film, (2) the epoxy-embedding for thin-sectioning technique, and (3) the microtome technique.
Direct Observation of Membrane Motion and Fluidity by Electron Microscopy
Authors: Hui S. W. 
Published: June 2020

Apart from a few studies on chemical reactions (1), the electron microscope is seldomly used for kinetic observations. The major difficulty in applying electron optical techniques to kinetic measurement had been the requirement that the specimen be placed in a vacuum. The recent development of environmental stages (2) has partially overcome this problem. The application of this technique to biological research will enable biological reactions to be observed in detail under a physiological environment.For studies of membrane motions, various molar mixtures of cholesterol, dipalmitoyl phosphatidylcholine and natural phosphatidylserine (extracted from bovine brain) were used. Unsupported bilayers were formed on fine mesh grids by dipping them through mono-molecular layers in a Langmuir trough (3).
The Regulation of Silica Incorporation Into the Stinging Cell Wall of Urtica Pilulifera
Authors: Sowers Arthur E. , Laurence Thurston E. 
Published: June 2020

Silicification in biological systems results from the polymerization of silicic acid (Si(OH)4) monomers (1). It has been reported (2) that silification takes place in a very characteristic way in the stinging cell wall(Fig. 1, arrow) of the “Stinging Nettle” (Urtica pilulifera). The cell wall is composed of an organic and an inorganic (silica) component, and the latter occurs in two phases: matrix and particulate (Figs. 2, 3, and 4).It can be postulated that macromolecular assembly in biological systems involves proteins with both catalytic and regulatory sites which probably have different substrate specificities and sensitivities. Germanic acid and several silanes with organic functional groups substituted in place of one or more of the hydroxyl groups in silicic acid are easily prepared from commercially available compounds. Such compounds make ideal analogues by which the regulation of this unique silicification can be studied.
The Fine Structure of Phialophora Mutabilis Grown on Various Media
Authors: Pardo Matias , Keller Betty , Pouchet Gail , Slifkin Malcolm 
Published: June 2020

Culturally and morphologically, P. mutabilis manifest wide variation in regard to pigmentation and colonial and microscopic appearance(1) . A composite of all the cultural characteristics of this fungus manifested only when a variety of media was employed for cultivation. Colonies grown on Sabouraud ' s dextrose agar, malt extract and Wort agar generally contained a central pigmented mycelial mat and a yeast-like peripheral zone. The colonies were completely yeast-like on corn meal agar. Microscopic examination from slide cultures on different media revealed conidia, chlamydospores and rare phialides.This is the first ultrastructural analysis of P. mutabilis. Culture from Sabouraud's dextrose agar were examined first. The outer surface of the hyphal cell walls is electron dense with a fibrillar network.
Ultrastructure and Morphology of the Neurospora Crassa Cell Wall Mutants, Slime And Slime X, Using Tem and Sem
Authors: Howard Karen S. , Braymer H. D. , Socolofsky M. D. , Milligan S. A. 
Published: June 2020

The recently isolated cell wall mutant slime X of Neurospora crassa was prepared for ultrastructural and morphological comparison with the cell wall mutant slime. The purpose of this article is to discuss the methods of preparation for TEM and SEM observations, as well as to make a preliminary comparison of the two mutants.TEM: Cells of the slime mutant were prepared for thin sectioning by the method of Bigger, et al. Slime X cells were prepared in the same manner with the following two exceptions: the cells were embedded in 3% agar prior to fixation and the buffered solutions contained 5% sucrose throughout the procedure.SEM: Two methods were used to prepare mutant and wild type Neurospora for the SEM. First, single colonies of mutant cells and small areas of wild type hyphae were cut from solid media and fixed with OSO4 vapors similar to the procedure used by Harris, et al. with one alteration. The cell-containing agar blocks were dehydrated by immersion in 2,2-dimethoxypropane (DMP).
Effects of Field Stimulation on Nerve Terminals in Human Blood Vessels.
Authors: Thureson-Klein Åsa , Stjärne Lennart , Brundin Jan 
Published: June 2020

Noradrenaline and dopamine ß-hydroxylase normally appear to be released from the nerve terminal by exocytosis and data from several laboratories indicate that, during severe stress, a close correlation exists between the level of these substances in the plasma and sympathetic activity. Ultrastructural evidence for exocytosis at the noradrenergic terminal in humans is lacking and it is not known if the large vesicle (LV) or small vesicle (SV) type, or both, are involved in the release process. The present study was performed to find morphological evidence of exocytosis.Portions of omental arteries and veins were obtained from patients undergoing abdominal surgery using routine general anesthesia. Control vessels were placed in fixative within 10-30 sec after excision, or they were treated similarly to experimental vessels except that field stimulation was omitted prior to fixation.