bluuebunny/crossref_metadata_2025_split huggingface dataset:
TEM cathodoluminescence of chemical vapor deposited diamond
Authors: Graham R.J. , Disko Mark M. , Moustakas T.D. 
Published: June 2020

Diamond films grown by chemical vapor deposition (CVD) are curently of great interest with potential applications in semiconductors and as wear resistant coatings. In order to understand and optimize the growth and properties of these films, it is necessary to characterize their microstructure. While such techniques as TEM and cathodoluminescence (CL) (in a SEM) can be used independently to provide microstructural and optical/electronic information respectively, the direct correlation of these two pieces of information is highly desirable. This is possible using the TEM CL technique (CL in a TEM) because the electron transparent specimen allows a direct comparison of CL with microstructure. The preliminary results obtained for CVD diamond films by this technique are presented here.The films examined were grown on a silicon (100) substrate by filament assisted CVD from a mixture of methane (2% vol.) and hydrogen at a pressure of 30 torr, using a tungsten filament operated at 1800°C.
The surface structure of GaAs(100) studied by RHEED and REM
Authors: Hsu Tung , Petrich G.S. , Cohen P. I. 
Published: June 2020

Three GaAs( 100) samples, each grown on a differently misoriented GaAs( 100) substrate, were prepared using molecular beam epitaxy (MBE) and characterized by in situ reflection high energy electron diffraction (RHEED) and ex situ RHEED and reflection electron microscopy (REM): A: the substrate is 2° off the (100) toward [011] (A misorientation),B: the substrate is 2° off the (100) toward (B misorientation), andC: the substrate is within 0.1° of (100) (Fig. 1).The goals were to compare the effects of MBE growth and oxidation on the different types of steps formed on these surfaces. Understanding the processes involved in promoting ordering of terrace lengths, and reduction of meandering and step bunching is crucial to current attempts to fabricate quantum wire structures.Samples were prepared by chemically etching the substrates and then growing 0.2μm of GaAs at 600°C, at a rate of 0.4μm/h, and using a 3:1 As:Ga flux ratio. Shapes of the in situ RHEED spots were used to measure the step configuration while the oscillation of RHEED intensities was used to determine the thickness of the grown film.
Diffusion of TEM grid material into amorphous silicon films
Authors: Kritzinger S. , Lombaard J.C. , Bedeker C.J. 
Published: June 2020

While investigating the silicide formation reaction between thin bilayers of amorphous Si (a-Si) and Cr, an unintended interaction occurred between the specimens and the supporting TEM grids. In an attempt to understand this phenomenon, the interaction between a single film of a-Si and TEM grids made of Cu, Ni, Au and Mo were investigated by in situannealing in a Siemens Elmiskop 101. The 60 nm films, prepared by e-beam evaporation of pure Si onto glass substrates, covered with an acetone-soluble release agent, were amorphous.In Fig. 1 the interaction between the a-Si film and a Cu TEM grid is shown. Areas I, II, III and IV in (a) show different stages of the interaction, area IV being closest to the Cu grid bar, and area I being pure a-Si. The reaction started at about 600°C by crystallisation of the a-Si film at different spots in contact with the grid bars, and fanned out from these nucleation sites (area II).
TEM and DSL photoetching investigations of Si-implanted LEC GaAs substrates
Authors: Frigeri C. , Weyher J. L. , De Potter M. 
Published: June 2020

Combined use of TEM and DSL photoetching (Diluted Sirtl-like etchant with Light) has been employed to investigate the origin of DSL etch features in ion implanted GaAs. The undoped, semi-insulating (001) LEC GaAs wafers were implanted with 29Si with fluences varying between 1.5-1012 and 3.0-1014 at/cm2. After implantation, rapid thermal annealing (RTA) was carried out at 900 °C for 10 s.The implantation damage was revealed by DSL in the form of microroughness in both as-implanted and annealed samples. The degree of microroughness varied according to the implantation dose and to whether the sample was as-implanted or annealed. A calibration by TEM was, thus, carried out in order to establish the nature of the underlying defects and the threshold implantation dose for their formation. To avoid the influence of the as-grown dislocations on the formation of the DSL etch features due to ion implantation, a shallow DSL photoetching was used as a preliminary step in the thin foil preparation procedure for TEM to clearly mark the dislocation cell structure. TEM observations were then performed inside the dislocation cells only.
Transmission Electron Microscopy characterization of epitaxial III-V semiconductor thin films grown on Si(100) by ion-assisted deposition
Authors: Hultman L. , Choi C.-H. , Kaspi R. , Ai R. , Barnett S.A. 
Published: June 2020

III-V semiconductor films nucleate by the Stranski-Krastanov (SK) mechanism on Si substrates. Many of the extended defects present in the films are believed to result from the island formation and coalescence stage of SK growth. We have recently shown that low (-30 eV) energy, high flux (4 ions per deposited atom), Ar ion irradiation during nucleation of III-V semiconductors on Si substrates prolongs the 1ayer-by-layer stage of SK nucleation, leading to a decrease in extended defect densities. Furthermore, the epitaxial temperature was reduced by >100°C due to ion irradiation. The effect of ion bombardment on the nucleation mechanism was explained as being due to ion-induced dissociation of three-dimensional islands and ion-enhanced surface diffusion.For the case of InAs grown at 380°C on Si(100) (11% lattice mismatch), where island formation is expected after ≤ 1 monolayer (ML) during molecular beam epitaxy (MBE), in-situ reflection high-energy electron diffraction (RHEED) showed that 28 eV Ar ion irradiation prolonged the layer-by-layer stage of SK nucleation up to 10 ML. Otherion energies maintained layer-by-layer growth to lesser thicknesses. The ion-induced change in nucleation mechanism resulted in smoother surfaces and improved the crystalline perfection of thicker films as shown by transmission electron microscopy and X-ray rocking curve studies.
Investigation of single crystals and epitaxial layers (EL) Of SiC by means of real color SEM technique
Authors: Mokhov E.N. , Chukichev M.V. , Roenkov A.D. , Saparin G.V. , Obyden S.K. , Ivanov A.I. 
Published: June 2020

Investigations were undertaken with SiC, a large-bandgap semiconductor material, that is rather promising for designing different optoelectronic devices. The characteristic feature of SiC is the availability of a large number of modifications, i.e. polytypes, strongly differing in the band-gap. The important problems that stand in the way of mastering SiC are the detectable doping of single crystals and epitaxial structures, the transformation of polytypes, and the structure of the intermediate layer. Crystals of SiC and its EL of 3C, 15R, 6H, 4H polytypes doped with N, Al, Ga and B were investigated. Single crystals were grown by the Leli method at T = 2600-2700°C as plates with basis planes {0001} . Epitaxial layers were grown by the sublimation "sandwich method" at T = 1700-2400°C in a vacuum or in an argon atmosphere.An analysis of the luminescence micrographs in the SEM and of the CL spectra shows that the distribution of impurities and polytype inclusions in single crystals considerably differs from that in EL. In the first case there occurs a striated inhomogeneity of CL across the whole width of the crystal which is obviously connected with an inhomogeneous distribution of dopes. Such a distribution of impurities was not observed in EL.
Characterization of zinc diffusion induced disordering in GaAs/AlGaAs multiquantum well structures by Transmission Electron Microscopy
Authors: Bourqui B. , Buffat P. A. , Ganière J.D. , Reinhart F. K. 
Published: June 2020

Diffusion of impurities, such as zinc or silicon, enhances the intermixing of Ga-Al atoms at GaAs/AlGaAs interfaces. This process is useful to modify the bandedge properties of multilayered structures such as (AlxGa1-xAs/GaAs). Important technological applications are due to this effect. Information about electronic states of the disordered structure is directly obtained by photoluminescence. The impurity induced disordering depth is, usually, estimated either by scanning electron microscopy (SEM) or by secondary ion mass spectroscopy (SIMS). We used transmission electron microscopy on wedge shaped specimen (WTEM) is used to obtain local information on the disordering depth and to check the chemical homogeneities of the diffused samples.The multiquantum well structures (MQW) were grown by molecular beam epitaxy (MBE) on n doped [001] substrate at surface temperature of 600 °C. A specimen structure is given in Figure 1. Zinc diffusions were performed by using the sealed quartz tube method at 575°C. The ZnAs2 source provide sufficient partial pressure of arsine to maintain the surface at equilibrium.
Cathodoluminescence characterization of two-dimensional interface structure of quantum wells
Authors: Wada Kazumi 
Published: June 2020

Exotic properties shown by quantum well structures, typical structures of future electron devices, are sensitive to interface roughness. Extensive studies are, thus, focused on characterization of interface structures. Recent improvement in quantum wire fabrication technology demands for characterizing not only perpendicular-interfaces to the growth direction but also parallel-ones (sidewall-interfaces). Such sophistication needs innovation in two-dimensional and nondestructive characterization technology.In device structures, interfaces are generally located deep in bulk. STM which visualize surface atoms can not monitor such interface. It is, thus, difficult to two- dimensionally characterize the interfaces.Interface steps induce well width fluctuation, which modulates optical transition energy between ground subbands in conduction and valence bands. Thus, interface step structures can be characterized by luminescence spectroscopy. Cathodoluminescence basically meets demand for nondestructive characterization of interface structures in two dimensions.
Image simulation as an aid for the interpretation of Electron Microscope images of magnetic structures
Authors: Zweck J. , Hoffmann H. 
Published: June 2020

An electron wave that passes through a magnetic sample of constant thickness d0 suffers a phase shift Δϕ which is proportional to the magnetic flux inclosed:where is a vector in the plane of the specimen. As is well known, this phase shift can be converted into an observable contrast by means of defocusing, quite similar as in the case of HREM imaging. However, realistic magnetic specimens are no ’weak phase objects’, therefore a complicated relationship between the experimentally observable contrast and the ’real’distribution of magnetization within the sample has to be expected. The approach to overcome these limitations in imaging of magnetic domains is closely related to the usual procedure well-known from HREM imaging: it is necessary to obtain an image under carefully controlled experimental conditions such as the amount of defocus and possible specimen tilt.
Electron radiation damage of natural zeolites at room and low temperature
Authors: Yokota Yasuhiro , Hashimoto Hatsujiro , Yamaguchi Terutoshi 
Published: June 2020

Zeolites are easily changed to amorphous under electron beam irradiation. Bando reported that this phenomena take place at low temperature with 1/20 dose of room temperature. In the present work this phenomena was investigated using two kinds of specimens, by changing temperature, electron energy (100 kV-350 kV) and also by applying an electron energy loss spectrometer.Mesolite is from Yaizu, Sizuoka Prefecture and Thomsonite is from Nishijima, Yamanasi Pref. , Japan. The specimen were ground to fine powder and dispersed on a microgrid. A Faraday gage which was installed in the observing chamber of the microscope was used for measure the dose rate. Decomposition was determined by measuring the current of a diffracted spot by the Faraday gage. Observation at low temperature was carried out using low temperature specimen holders fabricated to 200 kV and 400 kV electron microscopes.Fig. 1 (a), (b) are high resolution lattice images of Mesolite by 200 kV TEM operated in room temperature, (b) was taken 20 second after the same part of (a). The thickness of amorphous region in (a) is 8 nm, in (b) the amorphous region increased to 30 nm.
Dynamic observation on deformation and fracture of wool fibers
Authors: Dong Xuexi 
Published: June 2020

It’s no doubt that the investigation on the regularity of deformation and fracture of textile materials under tensile force has practical significance for determining their processing parameters and using conditions rationally. Particularly in recent years, textile materials have been increasingly applied to engineering fields of such as building and spaceflight etc. So people pay more and more attention to the study of deformation and fracture of them. SEM is one of important means for this study.Much information has been furnished which concerned with the behavior of fibers in deformation and fracture by studying the fracture morphology of materials with SEM. Some workers have observed the tensile courses and the fracture ends of fibers and obtained a lot of interesting results and important conclusions. But, so far, it hasn't been reported that how to measure the forces quantitively when deformation, lines and cracks emerging on materials . If the state of forces in fibers could be known during deformation and fracture, important advances would be achieved in this field.
Correlation of shearing properties with the structure of garment leathers
Authors: Lokanadam B. , Subramaniam V. , Ramasami T. 
Published: June 2020

Shearing property is of fundamental importance in influencing the complex deformations of a garment leather during use. The properties such as stretch, shape retention etc., are closely related to the shearing behaviour of garment leather. Although, textile fabrics have been investigated extensively for their shearing properties(1-3), the studies on leather have been limited. It is logical to expect the three-dimensional structure of leather and the intrinsic properties of collagenous fibre would be markedly different from those of other textile fabrics. The shearing property of a fabric can be expected to be influenced by its weave and matrix structure. An attempt has now been made to correlate the ultra and micro structural details of a garment leather with its shearing properties.A simple instrument has now been developed to assess the shearing behaviour of a soft fabric like garment leather. The shear test on garment leather involves the radial deformation of a sample piece by small degrees and measurement of the resultant shear stress and strain levels. Full chrome grain garment and suede garment leathers obtained from sheep skins were used for measurement of shearing properties.
EM observation on poly(β-alanine) crystal formed by the thermal solid State polymerization
Authors: Kimura Hirokazu , Sakabe Hiroshi , Morita Hitoshi , Itoh Takashi , Konishi Takashi 
Published: June 2020

It is well known that several ω-amino acids are polymerized in the solid state. A single crystal of ε-aminocaproic acid has been reported to be polymerized in the solid state to be the biaxially oriented nylon 6. We also reported in the previous paper that the thermal solid state polymerization of glycine single crystal produced poly(glycine-I) crystal.In this paper,structure of poly(β-alanine) polymerized in the solid state is investigated by means of scanning electron microscopy (SEM).transmission electron microscopy (TEM) and X-ray diffraction.Commercial β-alanine (Nakarai Tesque,Inc.,Kyoto) was recrystallized three times from the distilled-water solution (lg/ml) at 80°C. The single crystal continued to grow gradually during 24 hr. The obtained single crystals with rhombic habit had clear cleavage planes. These single crystals about 10 mm in size were used as the original specimens. The polymerization procedure was carried out on the single crystals at temperatures between 140 and 170°C in an evacuated and subsequently sealed tube.
An EM Study of silicone hydrophobicity in commercial gypsum wallboard
Authors: Freeman H. A. , Peters Y. A. 
Published: June 2020

Considerably improved performance is provided by gypsum construction wallboard which has been formulated to enhance durability and water resistance in applications that are susceptible to high humidity and moisture. One ingredient that is economically added in small amounts for this purpose is a low viscosity methyl hydrogen silicone fluid. The silicone was found to provide the necessary hydrophobic character and strength improvement when it was incorporated with the gypsum slurry in early stages of wallboard manufacture. However, it remained unknown where the silicone became localized to achieve this effect. Microanalyses were therefore performed in the analytical electron microscope to define the distribution of silicone in commercial gypsum wallboard samples.Gypsum samples were obtained which included those containing silicone and others to which no silicone had been added during manufacture. Analyses were performed in a JEM 2000FX analytical electron microscope operated at 200 keV and equipped with Tracor Northern Micro-ZHV and Microtrace energy dispersive x-ray spectrometers. Scanning (SEM), transmission (TEM), and scanning transmission (STEM) images were correlated with the mapped distributions of as many as six different elements acquired simultaneously. Low Z substrates and tilting specimen holders effectively minimized incorporation of spurious x rays in the final spectra.
A new equation to estimate trace rotation of planar features caused by double tilting of TEM specimen stage
Authors: Bande Hong , Qingchang Meng , Qing Liu 
Published: June 2020

Hirsch et al present an equation attributed to Presland and Pashley, which they infer can be employed to calculate the trace rotations of planar features during tilting. However, it is inapplicable due to the imperfection in theoretical consideration and it gives different results comparing to experiment as discussed in author’s paper.A new equation has been derived as shown in Figure 1. X and Y are the projectioas of tilt axes of double tilt stage on screen. OA is the intersection line of a planar feature intersecting with the foil surface, ψois the angle between OA and OX, it can be measured on screen (or on negatives) at foil normal orientation. To tilt a specimen to a new orientation [UVW] from [U0V0W0] , the tilt angle α and β can be calculated using the equations derived by the author’s, or read from the goniometer stage ia the light of diffractioa pattern. Suppose tilt the specimen around axis Y for β at first,the intersection line goes to OB, aad the trace on screen is OB’; then tilt the specimen around X for α, the spesimen attains its new orientation [UVW] and the intersection line goes to its final position OC. OD is the projection of OC, and the angle between OD and OX is ψ.
Nanoscale compositional changes in Cr-Mn steels α-bombarded at 773 K
Authors: Ruedl Erico , Valdrè Giovanni 
Published: June 2020

The structural materials for nearer-term fusion reactors such as ITER and DEMO will likely be steels. During their operation, the radiation damage in the structural components made of steels will become very complex since the damage is produced simultaneously by high energy neutrons, protons, α-particles and other particles. As long as no fusion device for material testing exists, data about the formation of radiation damage in candidate steels can only be obtained by simpler irradiating condition such as by neutrons with mixed energy spectra, protons and/or α-particles. The present work deals with a study of Cr-Mn austenitic steels, a category of materials of current interest in fusion technology because it is expected to produce less long term waste than Cr-Ni steels.The materials examined were: AMCR 0033 composed of ∼71wt% Fe, 17.5 Cr, 10.4 Mn, 0.53 Si, 0.2 N, 0.1 C; Nitronic 32 composed of ∼66.5 Fe, 12.3 Cr, 18 Mn, 1.5 Ni, 0.55 Si, 0.18 Cu, 0.35 N 0.1 C; AMCR composed of ∼71 Fe, 10 Cr, 17.5 Mn, 0.57 Si, 0.25 Cu, 0.2 C, 0.06 N.
High resolution TEM observation of shape memory alloy Ni-Ti at room temperature to high temperature
Authors: Li Yan , Hashimoto Hatsujiro , Sukedai Eiichi , Yokota Yasuhiro , Song Minghui 
Published: June 2020

Many investigations and applications of the reversible shape memory (RSM) alloys have been carried out since they were found in 1960 and the mechanism have been discussed extensively.In order to see the structure change of RMS-alloys in atomic scale on either side of the temperature of phase transformation, Ni-Ti alloy whose transformation temperature is 74 C has been heated inside of the 400kV (JEOL) electron microscope from room temperature to 230 C and atomic structure change has been recorded in TV and photographic films.Fig. 1(a) shows a structure of the electro-polished thin film of Ni-Ti alloy in (001) projection at room temperature, in which a martensitic structure is seen. As indicated in the figure, repeating twin structure whose twin boundary (T.B) is (100) and periodic black and white (B-W) contrast anomaly parallel to (110) in each twin bands are seen.Fig.1(b) is the enlargement of a region S in (a), in which the lattice fringes of (010) are seen on either side of T.B and B-W. Very small fringe shift is seen between B-W bands.
Microdiffraction analysis of precipitate crystallography and morphology in Al alloys
Authors: Muddle B.C. , Hugo G.R. 
Published: June 2020

Electron microdiffraction has been used to determine the crystallography of precipitation in Al-Cu-Mg-Ag and Al-Ge alloys for individual precipitates with dimensions down to 10 nm. The crystallography has been related to the morphology of the precipitates using an analysis based on the intersection point symmetry. This analysis requires that the precipitate form be consistent with the intersection point group, defined as those point symmetry elements common to precipitate and matrix crystals when the precipitate crystal is in its observed orientation relationship with the matrix.In Al-Cu-Mg-Ag alloys with high Cu:Mg ratios and containing trace amounts of silver, a phase designated Ω readily precipitates as thin, hexagonal-shaped plates on matrix {111}α planes. Examples of these precipitates are shown in Fig. 1. The structure of this phase has been the subject of some controversy. An SAED pattern, Fig. 2, recorded from matrix and precipitates parallel to a <11l>α axis is suggestive of hexagonal symmetry and a hexagonal lattice has been proposed on the basis of such patterns.
Microstructure of a solidified Al-Si-Fe-Cu alloy
Authors: Hidalgo-Prada B. , Maldonado E. 
Published: June 2020

Basic aspects of solidification can be examined by experimentation with the solidification processing followed by analysis of microstructural morphologies. The resultant structure depends on parameters such as the cooling rate, degree of undercooling, heat flow and growth rate.In this work, a commercial aluminum alloy of Al - 5.98Si - 0.50Fe - 3.00Cu - 0.06Mn wt%, have been solidified at intermediate cooling rate.Cylindrical specimens of 50 mm in diameter and 165 mm long were solidified from a superheating of 80 °C, by pouring the melt into steady state water-cooled metallic moulds. For microstructural analysis, small slices were cut from the ingot and prepared by polishing and etching using a solution of NaOH a t 70 °C by inmmersion for 5 minutes. The specimens were then cleaned in concentrated HNO3.The microstructural observations and x-ray microanalysis were done using an ISI-60 SEM.