bluuebunny/crossref_metadata_2025_split huggingface dataset:
How Small Is Too Small ? Understanding The Electronic Structure Of Atomic-Scale Transistors
Authors: D. A. Muller  , Sorsch T , Moccio S , Baumann F H , Evans-Lutterodt K , Timp G 
Published: July 2020

Abstract
The transistors planned for commercial use ten years from now in many electronic devices will have gate lengths shorter than 130 atoms, gate oxides thinner than 1.2 nm of SiO2 and clock speeds in excess of 10 GHz. It is now technologically possible to produce such transistors with gate oxides only 5 silicon atoms thick[l]. Since at least two of those 5 atoms are not in a local environment similar to either bulk Si or bulk SiO2, the properties of the interface are responsible for a significant fraction of the “bulk” properties of the gate oxide. However the physical (and especially their electrical) properties of the interfacial atoms are very different from.bulk Si or bulk SiO2. Further, roughness on an atomic scale can alter the leakage current by orders of magnitude.
In our studies of such devices, we found that thermal oxidation tends to produce Si/SiO2 interfaces with 0.1-0.2 nm rms roughness.
The Si/SiO2 Interface: Atomic Structures, Composition, Strain And Energetics
Authors: Pennycook S J , Duscher G , Buczko R , Pantelides S T 
Published: July 2020

Abstract
A number of recent studies of grain boundaries and heterophase interfaces have demonstrated the power of combining Z-contrast STEM imaging, EELS and first-principles theoretical modeling to give an essentially complete atomic scale description of structure, bonding and energetics. Impurity sites and valence can be determined experimentally and configurations determined through calculations.
Here we present an investigation of the Si/SiO2 interface. The Z-contrast image in Fig. la, taken with the VG Microscopes HB603U STEM, shows that the atomic structure of Si is maintained up to the last layers visible. The decrease in intensity near the interface could originate from interfacial roughness of around one unit cell (∼0.5 nm), or may represent dechanneling in the slightly buckled columns induced by the oxide. Fig. lb, taken from a sample with ∼1 nm interface roughness, shows a band of bright contrast near the interface. This is not due to impurities or thickness variation since it disappears on increasing the detector angle from 25 mrad to 45 mrad (Fig. lc), and is therefore due to induced strain.
Characterization Of SiO2/Si Interface Using Secondary Ion Mass Spectrometry(Sims) And Laser Post-Ionization Sputtered Neutral Mass Spectrometry(Snms)
Authors: Hayashi S , Yanagihara K 
Published: July 2020

Abstract
SIMS has inherent difficulties with quantification because of the so called “matrix effect”. Many factors contribute to the matrix effect, e.g. differing concentration of oxygen, sputtering rate differences in the hetero-layers, etc. In the case of MOS(metal-oxide-semiconductor) structures, the oxide layer gives rise to a large matrix effect. It is thus very difficult to use SIMS to evaluate the relationship between the electrical properties of the LSI devices and the impurity profiles present in such systems.
So we have been studying laser post-ionization SNMS, which consists of TOF-SIMS apparatus and excimer laser, in order to quantify the impurity profiles around SiO2/Si interface. Depth profiles of implanted Cu with 1×1015 atoms/cm2 in SiO2(100 nm)/Si system taken by Monte-Carlo simulation,SIMS and laser post-ionization SNMS are shown in Fig.l. In this implantation condition the Cu+:Cu2+:Cu3+ percentage ratios of the charge distributions were 44:42:14. Fig. 1(a) shows the theoretical depth profiles expetted from this implantation condition by Monte-Cairo simulation.
Study Of Single-Wall Carbon Nanotube-Supported Platinum Catalyst For Selective Hydrogenation Of The Carbonyl Function On An (α,β-Unsaturated Aldehyde
Authors: Lordi V , Yao N , Wei J 
Published: July 2020

Abstract
Supported Pt-metal catalysts are of immense commercial importance for hydrogenation reactions. The fine chemicals industry relies on special catalysts that selectively hydrogenate specific bonds or chemical functions on molecules. The activity, selectivity, lifetime, etc. of a supported hydrogenation catalyst is wellknown to depend strongly on the chosen support, but systematic studies of the role of the support and of support-metal interactions are lacking in the literature. The purpose of this work is to examine in detail the function of single-wall carbon nanotubes (SWNT) as support for a Pt catalyst, in the context of a selective hydrogenation reaction. The test reaction consists of the hydrogenation of the carbonyl group on 3-methyl-2- butenal, a reaction extensively studied on well-characterized Pt surfaces and also unsupported polycrystalline Pt. This reaction, which follows a parallel/consecutive reaction network (Fig. 1), represents a class of selective hydrogenation reactions of α,β-unsaturated aldehydes that are important in the fine chemicals industry for flavorings, fragrances, and some pharmaceuticals.
Conservation of superstructure at Ag/Si(l1l)--R30-Ag Interface observed by UHV-TEM
Authors: Oshima Y , Sigeki S , Hirayama H , Takayanagi K 
Published: July 2020

Abstract
A lot of efforts have been devoted to understanding an interfacial structure. But, there are some difficulties about it as follows: An interfacial structure depends on a surface structure of a substrate and its temperature. Also, an interfacial structure is not homogeneous in general because of a lattice mismatch between a substrate and an overlayer thin film.
Ultrahigh vacuum transmission electron microscope (UHV-TEM) is very powerful to observe clean surface and the fabrication during deposition on the surface. Since structural information can be obtained from 10 nm-sized area to a few μm area using TEM, UHVTEM is very appropriate to investigate interfacial structure in detail.
In this study, structure of Ag/Si(111)--R30-Ag interface was observed by UHVTEM. Especially, it is interesting whether the superstructure is conserved at this interface or not. The Si(l11)- as the substrate surface was obtained by Ag 1ML deposition on Si(l11) 7×7 surface at 673 K.
Transmission Electron Microscopic Study Of Heteroepitaxial Mechanism Of Cvd-Dlamond Grown On Pt(Lll) Substrate.
Authors: Zhou Guofu , Takai Yoshizo , Shimizu Ryuichi 
Published: July 2020

Abstract
Owing to its unique and outstanding physical-chemical properties, diamond is considered to be one of the most important potential materials for applications such as in mechanical, optical, thermal, and electronic devices. Among them, the most attractive application of diamond would be a semiconductor for high temperature and high power electronic devices. To realize such novel devices, a high quality of defect-free single-crystal diamond film is required. Recently, continuous diamond films are found to be able to grow on Pt(lll) substrate. Since the diamond film synthesized on Pt shows a high degree of epitaxy, this approach has drawn the attention of reseafchers in this field and some research results have been reported. However, the heteroepitaxial mechanism is still to be elucidated; in particular, why does diamond grow heteroepitaxially on the Pt substrate and how do the atoms align in the interface between diamond and the Pt substrate? In order to solve those problems, it is very necessary to study the diamond growth mechanism on an atomic scale.
Statistical Assessment Of Experimental Uncertainty In The Quantitative Analysis Of Strong-Beam A-Fringe Contrast.
Authors: Cohen Dov , Barry Carter C 
Published: July 2020

Abstract
Grain boundaries and related planar defects in crystalline materials are often characterized by relaxations from geometric lattice constructions in order to lower the interfacial energy. Grain boundaries may relax by local reconstructions of the atomic structure along the interface and/or rigid-body lattice translations that perturb the relative positions of the grains far from the interface. Rigid-body lattice translations can by studied using α-fringe contrast along planar interfaces in strong-beam transmission electron microscopy (TEM) images.[l-3] Oscillatory fringe contrast may appear along an interface between two grains which are related by a translation vector, R, when the interface lies inclined to the incident electron beam and imaged with a diffraction vector, g c, common to both grains.[4] The fringe contrast is due to an interference between the direct and scattered electron beams when the diffracted electron beams undergo a phase shift propagating across the interface. The phase shift, α, is proportional to the projection of R onto g c (i.e. α = Rg c) and the fringe contrast is known as α-fringe.
400 Kv Electron Cryo-Microscopic Imaging Of Large Icosahedral Viruses Towards Atomic Resolution
Authors: Jakarta Joanita , Chiu Wah 
Published: July 2020

Abstract
Three-dimensional structure studies provide important information about the organization of macromolecules, often revealing biological mechanisms and protein structure-function relationships. 400 KV electron cryo-microscopy is an emerging technology that is proving to be a powerful tool for studying the structures of large macromolecular assemblies that are often not tractable using other techniques. Its large depth of field makes it well-suited for imaging large objects to high resolution. In addition, a high accelerating voltage minimizes chromatic aberration yielding images of higher contrast. Recently a 400 KV electron cryo-microscope has been used to image periodic arrays of tubulin to 3.5 Å and single particles at somewhat lower resolutions (13 Å) providing practical demonstrations of its usefulness in modern structural biology. In this paper we present high resolution image data of two large icosahedral viruses: herpes simplex virus IB nucleocapsid (HSV IB) and rice dwarf virus (RDV). Human herpes virus (HSV) is associated with a spectrum of diseases ranging from cold sores to more severe clinical manifestations such as mental retardation.
Atomic-Resolution Z-Contrast Imaging Of Decagonal Quasicrystals: A Nucleation And Growth Mechanism
Authors: Yan Y , Pennycook S J 
Published: July 2020

Abstract
Though quasicrystals were discovered more than a decade ago, the fundamental questions of why and how quasicrystals form are still unanswered. Knowledge of atomic positions, for all species present, is the most important factor in trying to answer this question, and we have therefore applied Z-contrast imaging to this problem. The quasicrystalline structure, a state with long-range order, but no periodic translation symmetry, has been commonly described by the Penrose tiling model, in which two types of tile are connected according to strict matching rules. However, such a mathematical description does not provide any physical insight into how and why quasicrystals arise. An alternative description of the ideal quasicrystal has been given by Gummelt, who showed that the ideal quasicrystalline arrangement can be obtained with a single type of tile which is allowed to overlap so as to cover the surface. The equivalence of these two descriptions was proved by Steinhardt and Jeong.
Self-Assembling Of Ordered Mesoporous Titania Nanostructures
Authors: Yin JS , Wang ZL 
Published: July 2020

Abstract
Ordered self-assembly of nanocrystals is scientifically interesting due to not only the unique properties of the nanocrystals, but also the collective properties of the assembly. Compared to lithography method, self-assembly is limited by a lack of control over the sizes of the ordered arrays, resulting in difficulties in characterizing their physical and chemical properties. New techniques are needed to manipulate the self-assembling process and the nanostructures formed.
In this work, polystyrene (PS) spheres were used as the template to form large bulk ordered anatase nanostructure with cobalt doping. The ordered PS template was infiltrated with absolute alcohol solution of titanium butoxide. After the precursor was dried, it was treated at 160°C for 5 hours and then at 450°C for another 5 hours. To dope cobalt into the structure, the porous titania host was immersed in a heptane solution with cobalt carbonyl. After drying in vacuum at room temperature, it was treated at 160°C.
The Measurement Of Subtle Structural Changes In Yba2cu3O7-x By Processing High Resolution Tem Images
Authors: Barry JC , Alarco JA 
Published: July 2020

Abstract
Since the discovery of high temperature superconducting (HTS) ceramics there has been a great deal of discussion about theories of superconductivity. In a recent theory it has been proposed that the Tc's in these new materials are related in some way to a subtle phase separation in the structure. HTS ceramics have been studied quite intensively by high resolution transmission electron microscopy (HRTEM) and by electron diffraction (ED). In such studies the major focus invariably has been on the periodic structure of the object. However, early HRTEM work on Yba2cu3O7-x by Barry found that in addition to the crystalline order, the Yba2cu3O7-x HTS has a non-periodic structural modulation. In this work we have used an image processing method to look for subtle structural changes in Yba2cu3O7-x by measuring the bending of lattice fringes at twin planes. The image processing method is similar to the method used by Hetherington to study rigid body displacements at gold grain boundaries.
Soft Phonons and Anti-phase Domains in SrTiO3 : an Electron Diffuse Scattering Study
Authors: Wang Renhui , Zhu Yimei 
Published: July 2020

Abstract
It is well known that cubic SrTiO3 possesses a typical perovskite structure whose reciprocal unit cell is shown in Fig. 1 where X, M, and R designate particular points at Brillouin zone boundaries with the Γ point being the zone origin. The instability of the phonon mode designated by the R point leads to the cubic-to-tetragonal phase transition of SrTiO3 at Tc=103 K. By using the same unit-cell as the cubic SrTiO3, reflections (h k 1) / 2 with h, k, and 1 all odd are superlattice reflections characteristic of tetragonal SrTiO3. Previous investigations of diffuse scattering were carried out by neutron and xray diffraction at Temperatures below 240 K. In the present work, observation of the diffuse scattering was extended to a broad Temperature range of 20 ∼ 700 K.
Selected-area electron diffraction patterns (EDPs) reveal splitting and streaking of the superlattice reflections as shown in Fig. 2. We can see streaks along the [1 0 0]* direction, e.g., the streak connecting (5 3-5) / 2 and (7 3-5) / 2, the streak connecting (-3-5 7) / 2 and (-1-5 7) / 2. Splitting of the superreflections (7-1-1) / 2, (9-1-1) / 2, and (-7 1 1) / 2, along [0 1-1]* direction is evident. All the splitting and streaking behaviors shown in Fig. 2 and observed in other EDPs may be interpreted as being formed by the intersection of the Ewald sphere with reciprocal rods MRM shown in Fig. 1, which are along the &lt;100&gt;* direction passing through superlattice points.
Phase Identification Using EBSD in the SEM: What Can be Done Today and What we Hope to do Tomorrow
Authors: Michael J R 
Published: July 2020

Abstract
Phase identification using electron backscatter diffraction (EBSD) in the SEM has become a useful and important tool for the characterization of crystalline materials. Phase identification is accomplished using EBSD in the following manner. First, a high quality camera must be added to the SEM. Suitable cameras use slow scan CCD imagers coupled either by a lens or a fiber optic bundle to a phosphor screen that is situated near the sample. A EBSD pattern is collected and EDS or WDS is used to determine qualitatively the chemistry of the area. An automated routine is then used to extract the positions and widths of the lines in the pattern followed by a calculation of the unit cell volume. This information coupled with the chemistry of the sample is then used to search a database of crystal structures. Currently, the ICDD's Powder Diffraction file of over 100,000 compounds is used. Once a list of potential matches is found the patterns are indexed and then simulated to demonstrate that the phase has been identified. This paper will demonstrate use of EBSD for phase identification and then will speculate on future developments.
A particularly nice application of EBSD is the use of the technique for the identification of phases that form in welds. Figure 1a is an EBSD pattern obtained from a acicular phase in a superalloy weld. The phase was determined to be primarily Ti and Ni. Analysis of the patterns showed that the phase is Ni3Ti. Figure 1b shows the simulation for Ni3Ti overlaid on the experimental pattern demonstrating that the phase has been identified.
Texture Determination of Ceramic Materials by EBSD
Authors: Cosandey F , Markondeya Raj P , Cannon W R 
Published: July 2020

Abstract
Texture determination of ceramic materials is important in ceramic processing since it will ultimately govern the resulting material properties. For instance, recent results have indicated that preferred particle orientation leads to anisotropic shrinkage of tape cast ceramics. In this work, we report results on the effect of pressing as well as shearing during tape casting followed by sintering on particle orientation and texture development in ceramic materials. Oxides with different particle shape anisotropy and crystal structures have been investigated including tetragonal rutile titania (TiO2) and hexagonal alumina (A12O3).
Ceramic samples were processed by either pressing or by tape casting of a high ceramic particle loading aqueous suspensions. The samples were then pyrolized at 425°C followed by sintering for one hour at 1200 and 1500°C for TiO2 and A12O3 respectively. High spatial resolution Electron Backscatter Diffraction (EBSD) (OPAL-Oxford) in a field emission SEM (LEO-982) has been used for texture analysis and for crystallographic orientation determination of particles. Between, 3000 to 5000 measurements per sample were recorded automatically to develop an orientation map.
Texture Analysis of Earth Materials. Comparison of EBSD With Other Diffraction Techniques
Authors: Wenk H-R 
Published: July 2020

Abstract
An important feature of polycrystalline materials is the orientation distribution of crystallites also known as crystallographic preferred orientation or texture [1]. Conventionally it is measured by x-ray diffraction, averaging over sample surfaces. With demands for more quantitative material characterization, both in engineering and earth sciences, new methods have been developed. Two dimensions are of interest: Averages over larger sample volumes give a better representation to estimate bulk physical properties. Here neutron diffraction is advantageous. Because of minimal absorption large sample volumes (1-50 cm3), rather than surfaces can be analyzed [2]. If textures are locally heterogeneous, it may be of importance to analyze small regions. With a synchrotron microfocus beam volumes as small as 5 μm3 can be characterized [3]. These methods have been quantified and are extensively applied in metallurgy and geology. They provide good statistics for appropriate sample grain size but they analyze bulk textures and contain no information on local orientation correlations. Furthermore, for geological samples with low crystal symmetry, the diffraction patterns are often very complex with many overlapping peaks, making identification difficult. In such cases orientation imaging, using electron backscattered diffraction patterns (EBSD) in the SEM is useful [4]. Though grain statistics are generally much inferior, new information can be gained.
Extraction of Grain Boundary Energies from Triple Junction Geometry
Authors: Rollett A D , Yang C-C , Mullins W W , Adams B L , Wu C T , Bauer C L , Kinderlehrer D , Ta'asan S , Manolache F , Liu C , Livshits I , Mason D , Talukder A , Ozdemir S , Casasent D , Morawiec A , Saylor D , Rohrer G S , El-Dasher B , Yang W 
Published: July 2020

Abstract
Measurement of the geometry of triple junctions between grain boundaries in polycrystalline materials is used to generate large sets of dihedral angles from which maps of the grain boundary energy are extracted. A preliminary analysis has been performed for samples of magnesia and aluminum based on a three-parameter description of grain boundaries. An extended form of orientation imaging microscopy (OIM) was used to measure both triple junction geometry via image analysis in the SEM and local grain orientation via electron back scatter diffraction. Serial sectioning with registry of both in-plane images and successive sections characterizes triple junction tangents from which true dihedral angles are calculated. If there is local equilibrium at each triple junction, we may apply Herring's relation. By limiting grain boundary character to a (three parameter) specification of misorientation for the preliminary analysis, we can neglect the torque terms and apply the sine law to the three boundaries. This provides two independent relations per triple junction between grain boundary energies and dihedral angles. By discretizing the misorientation and employing multiscale statistical analysis on large data sets, (relative) grain boundary energy as a function of boundary character can be extracted from triple junction geometry. The results are discussed with respect to current understanding of grain boundary structure based on their crystallography. The results suggest that a three parameter characterization of grain boundaries (lattice disorientation) is not an adequate description of boundary character. A full analysis including torque terms and a five parameter boundary description is under development.
Grain Subdivision During Deformation Studied by Automatic EBSP
Authors: Juul Jensen D 
Published: July 2020

Abstract
During plastic deformation of typical metals the original grains subdivide. Subdivision by cell formation is a well-known phenomena in metals with medium to high stacking fault energy, but the subdivision may also take place on larger length scales by: i) Formation of single-walled dense dislocation walls (DDWs) and/or double-walled microbands (MBs). The DDWs/MBs are seen as elongated, nearly straight, vertically parallel dislocation boundaries which delineate several cells, thus bounding cell blocks. Typical examples are shown in Fig. 1. ii) Subdivision on a grain scale, for example due to grain-grain interactions or due to the formation of transition bands separating matrix bands. This subdivision is typical for both single crystals and polycrystals. For a general description and recent overview, see [1, 2].
The grain subdivision depends on the orientation of the grains. The morphology may appear different in grains of different orientations and the DDW/MBs can be parallel or inclined to a slip plane.
Investigation of γ/γ' Alloy by Simultaneous EDS and EBSP Analysis
Authors: Sutliff J A , Sitzman S D 
Published: July 2020

Abstract
This work describes an investigation of the microstructure of a γ/γ' Ni-base superalloy using the automated Electron BackScattering Pattern (EBSP) technique with simultaneous energy dispersive x-ray spectrometry (EDS). The goal of the investigation was to determine if EDS measurements necessary to discriminate γ' from γ' could be obtained when acquired simultaneously with a normal, high speed automated EBSP scan. The acquisition conditions that impact the EDS collection are: surface tilted ∼70 degrees from the beam axis, 70mm spectrometer to specimen distance limited by interference from the EBSP detector and approximately 300 ms available acquisition time.
Thermo-mechanical processing of superalloys can produce coarse γ' that appears both within grains and at grain boundaries. In some conditions, the coarse γ' may be as large as many γ grains. As the crystal structure of γ and γ' are very similar, it is not possible to discriminate between the two phases using typical EBSP analysis. However, one needs to discriminate these phases in order to measure properties of the γ matrix such as texture and grain size.