bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transmission electron microscopy of 1/4-micron SOI structures
Authors: Conner J. R. , Theodore N. D. , Arney S. C. , Carter C. B. , MacDonald N. C. 
Published: June 2020

As silicon devices are scaled into the submicron regime, parasitic circuit elements due to wiring and junction capacitance become increasingly significant. One way to reduce these parasitic elements is to fabricate circuits in thin silicon layers on an insulating substrate. Silicon-On-Insulator (SOI) structures can be fabricated by various techniques, including ion implantation of oxygen, recrystallization of amorphous or polycrystalline silicon films deposited on insulating thin films, and oxidation of porous silicon. A new SOI technique, in which islands of silicon become isolated from the silicon substrate during a thermal oxidation step, has been optimized for submicron-width silicon structures. The large stresses associated with the two-dimensional oxidation give rise to the generation and propagation of dislocations in the silicon island during the oxidation sequence. The characterization and removal of these dislocations is an important factor in optimizing these structures.TEM samples have been prepared to evaluate the defect configurations present in these novel submicron SOI structures.
Investigation of CPE/PVC morphology via STEM
Authors: Rightor E. G. , Garcia-Meitin E. I. , Liou D. W. 
Published: June 2020

Microscopic characterization of the phase morphology of poly(vinyl chloride) (PVC) modified with chlorinated polyethylene (CPE) is vital to understanding the blend physical properties. A 2-3 week CPE selective staining technique, developed by Fleischner et al., has been the mainstay for recent TEM investigations of CPE/PVC. Several researchers employing this method have reported a network structure of CPE surrounding primary PVC particles.Rapid electron beam-induced dehydrochlorination of chlorinated polymers prohibits TEM examination of unstained sections. Chemical changes resulting from such dehydrochlorination of polymers was addressed recently by Vesely and Finch. In this study we investigated unstained thin sections, obtained at ambient temperature with a diamond knife, by scanning transmission electron microscopy (STEM) on a JEOL 2000 FX.As the STEM micrographs show (Figs. 1-3), sufficient contrast was available to distinguish CPE (light phase) from the PVC matrix (dark). Differences in initial chlorine concentration and rates of beam-induced mass loss most likely account for the contrast between phases.
Thin film standardless analysis used in TEM asbestos EDS analysis
Authors: Li X. , Xingxing J. , Zi-qin W. , Lee R. J. , Dunmyre G. R. , Anderson K. L. 
Published: June 2020

A thin film standardless analysis method, based on the Cliff-Loriner factor k, has been used to do quantitative x-ray analysis of asbestos fibers in the TEM. The results of the analysis of four minerals at 120 keV were close to the theoretical value. The ionization cross section Q has been revised experimentally to improve the analysis of asbestos.The Cliff-Lorimer factor has been used in TEM thin film analysis since 1975. The factor kAB is used in the following equation:CA/CB= kABIA/IBwhere CA and CB is the weight percent of the elements A and B. The IA and IB are x-ray intensities corresponding to elements A and B. In this paper the calculated k values2 will be used for standardless quantitative analysis.In the thin film, when the effects of the backscattering electron, x-ray absorption, and secondary fluorescence are not considered, the x-ray intensity iswhere pt is the mass depth AA is the atomic weight of element A, W is the fluorescence yield, L is the ratio of the x-ray lines and T is the detector efficiency.
Monte-Carlo simulation of intensity ratio Is/Ic from substrate and film to determine the film thickness
Authors: Guangxiang Jin , Jianlin Li , Li Xu , Ziqin Wu 
Published: June 2020

The methods of thickness of film on substrate by electron probe have been published in literatures. It may be carried out simply by constructing a calibration curve from x-ray intensity measurments made on a series of films with known thickness on substrate.Sweeney et al. obtained a calibration curve based on a calcula- tied x-ray Ø(p z). As the calculation of Ø(p z) is difficult, Cockett and Davis, proposed using the experimental Ø(p z) of Castaing and Descamps. Bishop and Poole utilised Ø(p z) established by Monte-Carlo calculation for calibration curve.Huchings' method took into account the different electron scattering and absorption in the film on substrate and the bulk standard.Reuter et al., constructing a curve of Ic/Ib (Ic, intensity of the film on substrate; Ib, intensity of bulk standard) versus electron accelerating voltage E, exterpolate the curve so that Ic/Ib equals to 1, the excited x-ray depth obtained is just equal to the thickness of the film. The thickness of the film can be obtained by the use of an appropiate equation of excited x-ray depth.
Results on obtaining structural and analytical information with high lateral resolution in a STEM
Authors: Hubert G. , Krisch B. , Willasch D. 
Published: June 2020

A unique feature of high-performance STEMs is their ability to combine high-resolution imaging with the possibility to perform structural and chemical analysis in areas considerably smaller than 10 nm. The STEM ELMISKOP® ST 100 F has been used to demonstrate some of the potential applications in various modes of operation.Lattice imaging and defect analysis: It is well known that the unit cell charge distribution of certain crystals can be imaged in phase contrast TEM for structure determination and the investigation of lattice defects on an atomic level. In STEM one can obtain similar lattice images in phase contrast using a small-angle detector which samples the interference pattern in the detection plane between the undiffracted and at least one Bragg-diffracted wave (indicated in Fig.la by their wave vectors). Two ways of arranging the detector are possible: For axial (Fig.1a) or symmetrical imaging conditions (Fig.lb). Axial imaging includes instrument-induced chromatic aberration and yields an isotropic transfer function, symmetrical imaging excludes chromatic aberration but leads to an anisotropic transfer function not suitable for most applications.
Reduction of aberrations by new optimization techniques
Authors: Szilágyi M. 
Published: June 2020

A novel method has been proposed by the author for minimizing the aberrations of electron optical systems [1ś. The method involves restricting the possible electrostatic or magnetic field distributions to those connecting the intersection points of a rectangular computational grid by straight lines and gives a recursive algorithm for choosing distributions that minimize a given combination of aberration coefficients.The application of this method to the minimization of the spherical aberration of round magnetic lenses leads to interesting results [2ś. A graph of optimized h(z) distributions of the reduced flux density along the optical axis is shown in Fig. 1 for the case of δ = Δh Δz = 0.005 where Δh andΔz are the linear dimensions of a unit cell of the computational grid. In this case the object is immersed into the field at z = 0. A rich variety of different field distributions has been obtained.
Compensation of aberrations of deflected electron probe by means of dynamical focusing with stigmator
Authors: Baba Norio , Ito Yasuhiro , Kanaya Koichi 
Published: June 2020

An electron beam passing through a deflecting field is, in general, subject to aberrations such as distortion, astigmatism and coma in accordance with the deflecting angle. Accordingly, aberration defects of deflected beam are most serious limiting factor in performance of high resolution scanning electron microscopes.Based on the aberration formula(Wendt 1942, 1947 and Glaser 1956a), the distorted spot patterns of an electron probe deflected at two dimensional directions are calculated by using the conventional form of deflector field f (z) = [1+(z/a)2]-m. The important compensation conditions are induced by means of dynamical focusing with the stigmator.1] Field distribution and magnitude of deflectionThe magnitude of deflection by the electro-static field is given by,where E(z) is the axial field strength, Φ the accelerating potential, and za and zb are the co-ordinates of the entrance and specimen position, respectively. Now, assuming the function E(z)/Eo=[1+(z/a)2]-m (1) which corresponds to the axial field strength distributions of semi-infinite co-planar sheets(m=l/2), parallel cylinders or wires(m=l) and parallel plates with fringing effects(m=l∼5), deflection distances e and angles |e'|=α for various deflection geometry can be expressed analytically.
Advantages and limitations of a condenser objective for minimum exposure
Authors: Herrmann K.-H. , Kowalsky U. , Kunath W. , Weiss K. , Zemlin F. 
Published: June 2020

A single field condenser objective permits the imaging of a diaphragm onto the specimen such that areas with diameters smaller than 1000 Å can be illuminated. Combined with an electronic deflection system, this feature is particularly advantageous for radiation-sensitive specimens which should be exposed for the minimum dose required by the recorder.This method is preferable to others which, for example, require mechanical movement of the stage. In addition it can be directly combined with electronic image recording systems [1].A two-stage deflection system fabricated by printed circuit techniques [2] can be readily fitted into the upper part of the objective. The printed pattern is such that the current produces an almost homogeneous deflecting field. A second one-stage deflecting system in the intermediate lens system provides automatic retracking of the image such that by suitable control only the image with respect to the detector is moved, and not the illuminated region
Electrostatic energy analyzers for electron microscopes
Authors: Ovsyannikova L.P , Yavor S.YA. , Ioffe A.F. 
Published: June 2020

The application of energy analyzers in electron microscopy, the raster one in particular, is an interesting and comparatively new trendI-3. The analyzers can be used, for instance, for separating the elastically and inelastically scattered electrons, which leads to substantial improvement of the image contrast, and, accordingly, the space resolution. Monoenergetic images of a specimen obtained with energy analyzers permit of judging the topography of the specimen surface in connection with various physical properties of the specimen.At present, cylindrical mirrors are usually used as the analyzers for the above purpose. They are applicable, however, only for wide angle beams (the optimal angles lie within the range of 40°-50°).We propose an energy analyzer designed to operate both at narrow and wide angles of beam.The analyzer consists of two coaxial electrodes in the shape of surfaces of revolution, i.e. hyperboloids, paraboloids, cones (Fig.). Ringed windows (I,2) are cut in the electrodes for passage of a beam which has the form of a hollow cone.
The ANL HVEM-tandem accelerator facilities
Authors: Lyles R. , Taylor A. , Merkle K. , Okamoto P. , Pronko P. 
Published: June 2020

The ANL HVEM-TANDEM accelerator facilities are being developed to provide a unique combination of techniques for basic studies in the field of materials science. In addition to the methods of high voltage electron microscopy, the ion accelerator system will provide ion beam analysis and ion bombardment - implantation capability either in the HVEM or in an adjacent target area. The installation of the HVEM is completed and constitutes the first step in the development of a materials research laboratory, which will include a HVEM/ion beam interface with a 300 kV ion accelerator and a 2-MV tandem accelerator. The plan layout of these facilities is shown schematically in Figure 1.ANL's 1.2 MeV HVEM is an improved version of the AEI EM-7 and has a guaranteed resolution of 5 Å point-to-point. The design of the microscope contains a number of unique features. These include a specially designed ion beam access flight tube, instrumentation for two independently adjustable dark field conditions, 100 - 1200 kV continuous-mode accelerating voltage selection, a negative ion trap, and an ion- pumped specimen chamber.
The use of scintillation detectors in the STEM
Authors: Wiggins J.W. 
Published: June 2020

There are several characteristics desired of an electron detector that is to be used in a STEM. Depending on the particular instrument, one would like to have some or all of the following characteristics. It should have an output fast enough to keep up with the fastest scan rate of the microscope and should not introduce any noise into the signal. It should allow fabrication into sophisticated geometries required by some contrast mechanisms; for example, as an annulus for dark field contrast or as a sharp, straight edge for use as a spectrometer slit. Finally, it should have a high resistance to radiation damage by the electron beam.Single crystals of europium-activated calcium fluoride [CaF2(Eu)] have been used as scintillation detectors because they satisfy all of the characteristics proposed above and are not even very expensive.The complete electron detector consists of an appropriately shaped scintillator, a light-collection device, and a photomultiplier to convert light to an electrical signal.
Multi-purpose backscattered electron detector
Authors: Kikuchi M. , Takashima S. 
Published: June 2020

Backscattered electrons (BSE) permit a variety of information regarding the specimen, e.g., composition, topography, magnetic domain structure, crystalline states, etc., to be obtained. However, since conventional BSE detectors are all single-purpose designed, several different detectors are required to obtain the required variety of information.In order to circumvent this inconvenience, we have developed a multi-purpose BSE detector system. As shown in Fig. 1, the detector can be freely rotated around the specimen surface. In addition to which, the distance between the detector and the specimen can be varied. The newly developed solid state detector used in this system possesses high sensitivity and high response characteristics. Some advantages and applications of the system are given below.1. By setting the detector at the low and high takeoff angle positions, topographic contrast and composite contrast (Z-contrast) can be respectively enhanced.2. By using the rotation and distance varing mechanisms in combination, the optimum detecting condition for ensuring a good magnetic domain image can be selected.
X-ray micro tomography in the scanning electron microscope
Authors: Brünger W. 
Published: June 2020

Reconstructive tomography is a new technique in diagnostic radiology for imaging cross-sectional planes of the human body /1/. A collimated beam of X-rays is scanned through a thin slice of the body and the transmitted intensity is recorded by a detector giving a linear shadow graph or projection (see fig. 1). Many of these projections at different angles are used to reconstruct the body-layer, usually with the aid of a computer. The picture element size of present tomographic scanners is approximately 1.1 mm2.Micro tomography can be realized using the very fine X-ray source generated by the focused electron beam of a scanning electron microscope (see fig. 2). The translation of the X-ray source is done by a line scan of the electron beam on a polished target surface /2/. Projections at different angles are produced by rotating the object.During the registration of a single scan the electron beam is deflected in one direction only, while both deflections are operating in the display tube.
Reduction of contamination in analytical electron microscopy by using specially designed cold traps
Authors: Tomita T. , Harada Y. , Watanabe H. , Etoh T. 
Published: June 2020

For conventional transmission electron microscopy, specimen contamination is not so important as to take it into account, because recent electron microscopes are designed so as to provide the specimen chamber with a vacuum of the order of 10-7Torr. However, in analytical electron microscopy, contamination still presents serious problems requiring solution, because a very fine electron probe (less than 200Å) remains stationary on the specimen for a few minutes. In this case, a contamination spot is formed by the reaction of the electron probe with hydrocarbon molecules adsorbed on the specimen surface. The present paper describes detailed observations of contamination spots caused by very fine electron probe and the reduction of contamination spots by means of a specially designed liquid nitrogen cold trap assembly.This cold trap assembly shown in Fig. 1 consists of two traps; an inner trap and outer trap. The inner trap, which is a conventional type, is designed to enclose the specimen.
Stereo imaging in the shadow electron microscope
Authors: Dowell W. C. T. 
Published: June 2020

Stereo imaging is not new to electron microscopy. Von Ardenne, who first published transmission pairs nearly forty hears ago, himself refers to a patent application by Ruska in 1934. In the early days of the electron microscope von Ardenne employed a pair of magnetic lenses to view untilted specimens but soon opted for the now standard technique of tilting the specimen with respect to the beam.In the shadow electron microscope stereo images can, of course, be obtained by tilting the specimen between micrographs. This obvious method suffers from the disadvantage that the magnification is very sensitive to small changes in specimen height which accompany tilting in the less sophisticated stages and it is also time consuming. A more convenient method is provided by horizontally displacing the specimen between micrographs. The specimen is not tilted and the technique is both simple and rapid, stereo pairs being obtained in less than thirty seconds.
Epitaxial growth of very thin films of germanium
Authors: Hoeike C.W. 
Published: June 2020

The preparation of germanium electron microscopy specimens by chemically polishing slices cut from a single crystal is a standard technique (1). Also, epitaxial growth of germanium on crystalline substrates has been achieved by vapour deposition (2,3). However, the selfsupporting very thin films required for high resolution, crystal lattice imaging experiments cannot be easily prepared by either method.A uniform amorphous film of germanium of any desired thickness can be prepared, however, by vacuum evaporation of germanium from a tungsten basket onto a suitable substrate at any temperature below 500 K. This amorphous film will crystallize when heated to 675 K or more (2). By controlling the heating of the substrate during evaporation and subsequent crystallization, it is possible to induce epitaxial film growth on single crystal substrates.The work described here has established the conditions necessary for the growth of germanium single crystal films 140Å thick, with [111] and [100] surface orientations.
A sputter source for electron microscopic preparation
Authors: Jakopić E. , Brunegger A. , Essl R. , Windisch G. 
Published: June 2020

Coating electron microscopic specimens by sputtering yields particulary fine grained coatings of strong adherence. Two methods have been applied up to now. Their difference lies in the arrangement of target and specimen. If, in one case both, target and specimen are arranged inside the discharge chamber,damage by the discharge of sensitive specimens is possible (Fig.la). If, in the other case both, target and specimen are arranged outside the discharge chamber, focussing of the ions is necessary, above all for shadowing (Fig.lb).Simple ion guns of low energy (some keV) however, yield a relatively low ion current, so that coatings with materials which are difficult to sputter, such as tungsten, can hardly be produced. With ions of higher energy the gain of sputtering particles would certainly increase. However, the danger arises that ions scattered at the target and neutral particles of high energy could damage the specimen.The basic idea of the new sputter source consists of arranging the target inside the discharge chamber but the specimen outside of it (Fig.2).
Fourier spectrum analysis of phase contrast of support film
Authors: Oikawa Tetsuo , Ishigaki Fumiko , Hojou Kiichi , Kanaya Koichi 
Published: June 2020

In high resolution electron microscopy, it is most important to determine the defocus of electron micrographs of amorphous support films. The variation of spatial frequencies of phase contrast of support films was obtained from the phase shift of the electron waves caused by defocus and spherical aberration as well as the atomic phase, which are demonstrated by use of optical Fourier transforms. The spatial frequencies of phase contrast of films of tungsten, prepared by ion bombardment, which are useful as support films for high resolution electron microscopy, has been discussed analytically.Taking account of atomic phase shift, the transfer function, which was originally presented by Thon (1966), was modified. Optical Fourier transforms are in similar to the calculated Fourier transforms of corre- sponding computed images. Accordingly, it turned out that the atomic phase shift should not be neglected. The thickness of tungsten film, in case of less than 2 nm thickness, can be determined by comparing the optical Fourier transforms with the calculated ones.
Bright-field image contrast and resolution in STEM and CTEM
Authors: Cowley J. M. , Au Andrew Y. 
Published: June 2020

For the high resolution imaging of thin specimens, it has been shown by Cowley and Au that the bright-field image intensity may be written asHere s(r) and c(r) are the two-dimensional Fourier transforms of the imaginary and real parts of the transfer function, A(u)sinx(u) and A(u)COSX(u), where A(u) is the aperture function, x(u) is the phase factor usually writtenand u = (2sinθ)/λ is the magnitude of the two dimensional reciprocal space vector u;Δf and Cs are the defocus and spherical aberration constants of the objective lens and the * symbol indicates a convolution integral. In deriving equation (1) we have assumed the validity of the phase object approximation but not the usual weak phase object approximation (WPOA) which applies only for the weak-scattering case that σφ(r)<<l, where σ is the interaction constant (=п/λE) and ϕ(xy) is the projected potential of the object. The WPOA is known to have severely restricted validity for crystalline specimens or for specimens containing heavy atoms such as negatively stained or positively stained biological material.
Dark-field STEM imaging and diffraction calculations of heavy atoms on amorphous support films
Authors: Krakow William 
Published: June 2020

It has been noted by several investigators that the observation of single heavy atoms and small molecules in a high resolution electron microscope depends upon the discrimination between the image of the specimen and the support film used. Neglecting statistical noise due to the number of electrons the possibility of contaminant heavy atoms or structural noise caused by local arrangements of support film atoms remains.To evaluate the effect of the interference of scattered wavelets from a few atoms in a support film a model of a 10Å thick amorphous film was obtained using random number generators. The atoms were then packed in a 100 x 100 x 10Å volume until the density of amorphous carbon was attained (2400 atoms) with the constraint that the atoms could not be closer together than the nearest neighbor distance in carbon (1.5Å). A system of computer programs was then employed to simulate microdiffraction patterns and dark-field scanning transmission electron microscope (STEM) images.