bluuebunny/crossref_metadata_2025_split huggingface dataset:
Theoretical Investigations of RHEED Oscillations
Authors: Mitura Z , Dudarev SL , Whelan MJ 
Published: July 2020

Abstract
Nowadays there is great interest in the application of reflection high energy electron diffraction (RHEED) to monitor the growth of ultra thin films. This popularity of RHEED arose from the discovery of RHEED intensity oscillations in the early eighties. Namely, it was experimentally found that if the growth of a material follows a layer-by-layer mode then regular oscillating changes in the intensity of the specular beam occur, and the period of the oscillations corresponds to the deposition of one atomic layer of the material. These findings are of great practical importance and consequently RHEED is an important experimental technique used in nanoscale engineering. Nevertheless, the basic question of why RHEED oscillation are observed still remains open. In the past the Philips group suggested that intensity oscillations are a consequence of periodic changes in the roughness of the surface. About the same time, the University of Minnesota group claimed that during the growth the electron wave is reflected by two terraces (in an idealised case) and periodic changes of the interference conditions imply RHEED oscillation.
Inner-Shell Damage Thresholds Below 1kv in Cu-Phthalocyanine
Authors: Chen Q , Spence J , Stevens M , Weierstall U 
Published: July 2020

Abstract
In 1970, Breedlove and Trammel predicted that, because of radiation damage, the direct imaging of individual organic molecules by electron or X-ray microscopy was not possible. This follows from an analysis, above IkeV, of the beam energy dependence of the ratio of inelastic scattering cross sections (some of which causes damage) to elastic cross sections (used to form the image). To minimize damage, we have therefore constructed a transmission electron microscope with nanometer resolution, which operates at 7 - 300 eV, below the threshold for most inelastic processes. Recently we have obtained our first images of TMV with this instrument. Isaacson first suggested that the K-shell ionization of carbon may be the most important damage process. Although less probable than valence excitation, it dumps more energy into the system, and the decay products are highly damaging. A subsequent study of electron beam damage in several π- bonded hydrocarbon crystals down to about 200 eV showed that a damage threshold does exist at about IkeV incident energy which can be explained by the carbon K-shell ionization. (Multiple scattering increases the energy threshold from 285eV).
Structural Fluctuations in Metal Nanoparticles
Authors: Tanaka Miyoko , Takeguchi Masaki , Furuya Kazuo 
Published: July 2020

Abstract
The structure of small particles attracts great interest for their distinctiveness. Small particles of several materials undergo lattice parameter change or crystal structure change and sometimes form multiply twinned particles (MTPs) [1]. Configurational and structural fluctuations which they show under electron beam irradiation are also interesting phenomena [2]. This quasi-molten state are well explained theoretically [3], but the exact cause of it is still a matter of debate [2,4].
To clarify the behavior of nanoparticles under electron beam more precisely, we grew indium, palladium and molybdenum nanoparticles on Si (110) TEM samples in situ and investigated with an ultrahigh vacuum field emission transmission electron microscope (UHV-FE-TEM). It is a JEOL-2000VF operated at 200 kV with a base pressure of the column less thari 2.0 x 1O−8 Pa. Two kinds of evaporators are attached to the column in order to perform in situ evaporation of metals; an electron beam (EB) evaporator for high melting temperature material and a thermal heating evaporator with tungsten wire for low melting temperature ones.
Visibility of Small Metalllic Catalyst Particles in High-Resolution Secondary and Backscattered Electron Images
Authors: Liu Jingyue 
Published: July 2020

Abstract
Metallic nanoparticles finely dispersed onto high surface-area supports play an important role in heterogeneous catalysis. The performance of a supported metal catalyst can be directly related to the size and spatial distribution of the metallic nanoparticles. With the recent development of highresolution SEM instruments, it is now possible to observe nanoparticles in a field emission SEM. At low voltages, surface details of catalyst supports as well as metallic nanoparticles can be observed. The particle contrast in low voltage SEM images, however, is still not well understood. We have previously shown that the contrast of metallic particles can be enhanced if a small positive potential is applied to the sample. It is suggested that backscattered electrons (BE) significantly contribute to the visibility of metallic nanoparticles in high-resolution SE images. In this paper, we report further study on the origin of particle contrast in high-resolution SE images.
Figure 1 shows a set of SE images of the same area of a carbon supported Pt catalyst.
Defect Structures in Semiconducting Resi2−x Epitaxial Thin Films
Authors: Misra A , Mitchell TE 
Published: July 2020

Abstract
Narrow band gap semiconductors such as ReSi2-x (Eg ∽0.12 eV) are potential materials for infrared detectors [1]. Further, ReSi2-x is in thermodynamic equilibrium and has a very small lattice mismatch with Si offering the potential of developing ReSi2-x /Si heterojunction devices where the detector element and the signal processing circuitry can be integrated on one Si chip. In a previous study, strong crystallographic alignment between ReSi2-x film and (001)Si substrate was observed by ion channeling [1]. In this study, a transmission electron microscopy (TEM) study has been performed on ReSi2-x epitaxial films on (001) Si. Comparisons are made to our previous microscopy study [2] on the defect structures in bulk single crystals of ReSi2-x.
ReSi2-x films were prepared by reactive deposition epitaxy (RDE) technique by evaporating Re onto (001) Si wafer at 650 °C. A cap layer of Cr was evaporated at room temperature. A bright field (BF) TEM image of the interface in cross-section is shown in Fig. 1 with the corresponding selected area diffraction pattern (SADP) shown in Fig. 2.
Analysis of Degraded Gold-Plated Surfaces in Contact With Lead-TiN Solder During Elevated Temperature Testing of 208- PIN Microelectronic Packages
Authors: Schaper Jake , Weberg Ron 
Published: July 2020

Abstract
This report provides analysis data on black deposits observed on gold-plated test socket pads. The socket pads are an integral part of a burn-in test where the test simulates an accelerated aging process and is routinely performed on new products. The test consists of placing a device, as shown in Figure 1, with lead/tin plated copper leads in a test socket then placing that assembly into a “burn-in” oven set to a specific elevated temperature, 150° C in this case, for a specific time. Typically, a bias voltage is applied through the pads on the socket during the test. Historically, during extended burn-in tests of Quad Flat Pack (QFP) devices, problems arose when several devices unexpectedly exhibited open socket-to-device contacts. The “opens” problem repeated itself when new QFP devices were installed in the sockets. Upon visual inspection of the sockets, black deposits were observed in the contact regions, as shown in Figure 2.
Control of Si-Island Free Ultra-Thin Simox Structures by Implant Energy and Oxygen Dose
Authors: Johnson B , Jiao J , Seraphin S , Yan T , Wilson T , Anc M , Cordts B 
Published: July 2020

Abstract
To serve the needs of future submicron electronic applications such as cellular communications and character recognition, the computational elements have to be drastically reduced in size as well as power consumption. A promising approach is based on implantation of oxygen ions into a silicon substrate and subsequent high temperature annealing. The process when properly done, results in a very thin silicon layer separated from the bulk silicon substrate by a thin layer of silicon oxide. In these SIMOX elements the top silicon layer is seriously degraded by defects introduced by the ion implantation process, consequently affecting the performance of devices built on them. A careful selection of processing parameters such as implant energy and dose is essential in order to minimize the defect densities. It is believed that Si interstitials are the main reason for the formation of most defects in SIMOX [1]. Consequently, the reduction of the implant oxygen dose minimizes the Si interstitials, and finally lowers the defect densities in both the top Si and buried oxide layers.
Interface Voids and Precipitates in GaAs Wafer Bonding
Authors: Vanfleet RR , Shverdin M , Zhu ZH , Lo YH , Silcox J 
Published: July 2020

Abstract
Wafer bonding allows the production of Compliant Universal substrates that are made by bonding a thin (&lt; 10 nm) layer twisted ∼45 degrees to the underlying substrate. Subsequent growth on this twisted layer results in defect free films even when the growth material has a significant lattice mismatch with the substrate. Defects on the bonding interface are a common observation when bonding GaAs to many substrates, but the exact nature of these defects has not been clear. We have studied this bonding layer in GaAs-GaAs twist bonded structures by Scanning Transmission Electron Microscopy and Electron Energy Loss Spectroscopy and established that the defects are voids with a portion being partially filled with gallium. Two general sizes of voids are seen. The larger voids are approximately 45 nm in diameter and 22 nm in the wafer normal direction and are distributed in an approximately linear relationship.
Transmission Electron Microscope Characterization of Siz Selective Deposition of Si-Nanoparticles
Authors: Wu Hai-Ping , Nishimura Kimihiro , Kebaili Nouari , Fujinuma Haruko , Takayanagi Kunio 
Published: July 2020

Abstract
Nanosized semiconductors have been highly desirable as optoelectronic materials since the discovery of photoluminescence from porous nanostructured silicon. There are many investigations about visible light emission from nanostructured semiconductors, and several studies showed the size dependence of the photoluminescent and electronic property [1], [2]. In order to investigate the size effect of those optical properties of nanoparticles, the size-selection technique is important.
Size-selection of silicon nanoclusters has been carried out by crossing, an Ar molecular beam perpendicularly to the silicon cluster beam. The laser ablation in inert gas method was used for fabricating nanometer-sized silicon. Large size silicon clusters are produced by Nd:YAG laser irradiation of a silicon wafer which was rotating in ablation chamber under He-gas flow. Produced nanoparticles were extracted through a nozzle ( ϕ = 0.6 mm) to a differentially pumped chamber and then skimmed into a high vacuum chamber for size selection and deposition.
TEM Study of Amorphous Silicon Recrystallization
Authors: K Lam Lawrence , Jiang Nan , G Ast Dieter , Silcox John 
Published: July 2020

Abstract
Recently there has been increasing interest in nickel induced lateral recrystallization of amorphous silicon because of its potential to improve device performance and to lower the thermal budget during processing. The hypothesis is that the formation of nickel silicide provides a low energy nucleus for the recrystallization of amorphous silicon. The silicide, moving into a-Si, leaves crystalline silicon behind.1 The grains formed, therefore, tend to elongated. In this paper, we attempt to use TEM to investigate in detail the nickel assisted lateral crystallization of amorphous silicon. The sample was prepared by first depositing a 1000A thick low temperature, oxide layer, LTO, on Corning 1737 glass. A 1000A thick amorphous silicon layer, a-Si, and 1000A thick a-Si were deposited subsequently. The sample was pattern and etched with hydrofluoric acid to form lOum x lOum holes in the oxide layer. Next, 200A of nickel was evaporated onto the sample, followed by a 600°C, 6 hours anneal to induce lateral recrystallization.
Transmission Electron Microscopy Observation of 11MEV B5+ Ion Irradiation in Bi2Sr2CaCu2O7-x Single Crystal
Authors: Zhou WL , Sasaki Y , Ikuhara Y , C.J.O’Connor  
Published: July 2020

Abstract
Artificial defects generated by ion irradiation have been considered an efficient method to enhance the critical current density in superconducting materials. The mechanism of producing defects as flux pining centers is still an important issue since the efficiency of irradiation-induced defects in flux pinning strongly depends on their microstructures. Different types of defects have been found in heavy ion irradiation. However, there are few results that show light ion irradiation due to the target material selected, the type of light ion and energy, and the incident ion angle. Another factor is the difficulty of cross-sectional sample preparation. In this paper, a single crystal Bi2Sr2CaCu2O7-x with 11 MeV B5+ ion irradiation was observed by transmission electron microscope (TEM) from both plan and cross-sectional view.
The Bi2Sr2CaCu2O7-x single crystals used for ion irradiation were prepared using the floating-zone melting method. The crystals were cleaved into thin sheets of about 20 μm thickness along the a-b plane and cut to about 2mmx2mm size.
Observation of an Elementary Cuboctahedron Of Xe Nanocrystal in an Al Matrix
Authors: W. Allen Charles , C. Birtcher Robert , Furuyat Kazuo , Songt M , E. Donnelly Steven , A. Ryan Edward 
Published: July 2020

Abstract
When a noble gas element such as Xe is implanted in an fee metal matrix such as Al at room temperature, a fine dispersion of precipitates forms. The precipitates are elementary fee crystals up to diameters of several nanometers (for Xe in Al, 8-10 nm), above which they are non-crystalline. The precipitates exhibit a cube-on-cube orientation relation with the matrices and have lattice parameters which are much larger than those of the matrices (axe ≃ 1-5aAl). Thus the interphase interfaces are incommemsurate though the lattices are isotactic. The precipitates assume the shape of matrix cavities; for an Al matrix, at equilibrium this is a cuboctahedron, a {111} octahedron truncated at the corners on {100}. Fig. 1 is a sketch of a dispersion of such cuboctahedra, viewed approximately along a &lt;110&gt;.
For this study specimens were prepared in the HVEM-Tandem Facility at Argonne National Laboratory by implanting 35 keV Xe to a dose of 4x1019 m−2 into well-annealed 5N Al discs which had been thinned by jet electropolishing.
AES and SEM/EDS Analysis of Silvered Teflon Laminates of Optical Solar Reflector
Authors: Wang Len , Kiwak Robert , Kauder Lonny , Greer Gregory 
Published: July 2020

Abstract
The Optical Solar Reflector (OSR) of Earth Observing System-PM (EOS-PM) is made of a flexible function layer of silvered Teflon/Inconel/Kapton laminate bonded to a honeycomb panel. After having been thermal cycled in vacuum, the laminate/panel was irradiated in air with UV at 2.2 equivalent suns intensity for 500 hours. Severe darkening was observed in areas exposed to UV but little or no darkening occurred in adjacent but shaded areas. Drastic increase of absorptance was observed-due to the darkening.
In order to investigate the cause of the degradation, test samples were irradiated at different configurations for 1000 equivalent sun hours (ESH). These samples were freestanding laminates and irradiated in vacuum and air, respectively. No darkening was observed on the sample that was irradiated in vacuum. Severe darkening was observed on the sample that was irradiated in the air. A laminate sample was irradiated in dry nitrogen for 1000 ESR and found no darkening either.
EELS and Xanes Analysis of Plutonium and Cerium Edges From Titanate Ceramics for Fissile Materials Disposal
Authors: Fortner JA , Buck EC , Kropf AJ , Bakel AJ , Hash MC , Aase SB , Chamberlain DB 
Published: July 2020

Abstract
We report x-ray absorption near edge structure (XANES) and extended x-ray fine structure analysis (EXAFS) spectra from the plutonium Llll and cerium Lm edges in prototype titanate ceramic hosts for disposal of surplus fissile materials. These spectra were obtained using the MRCAT beamline at the Advanced Photon Source (APS). The XANES and EXAFS results are compared with electron loss spectra (EELS) determination of oxidation state from the plutonium MlV,V and cerium MlV,V edges [1,2]. The titanate ceramics studied are based upon the hafniumpyrochlore and zirconolite mineral structures and will serve as an immobilization host, containing as much as 10 weight % fissile plutonium, and 20 weight % (natural or depleted) uranium. Similar formulations were composed using cerium as a “surrogate” element, replacing both plutonium and uranium in the ceramic matrix. We find the plutonium to be present almost entirely as Pu (IV), while the cerium is clearly in a mixed III-IV oxidation state in the surrogate ceramic.
Microstructural and Compositional Characterization of SiC-On-Insulator Structures
Authors: Ishimaru Manabu , M. Dickerson Robert , E. Sickafus Kurt 
Published: July 2020

Abstract
As the size of Si integrated circuit structures is continually reduced, interest in semiconductor-oninsulator (SOI) structures has heightened. SOI structures have already been developed for Si using oxygen ion implantation. However, the application of Si devices is limited due to the physical properties of Si. As an alternative to Si, SiC is a potentially important semiconductor for high-power, high-speed, and high-temperature electronic devices. Therefore, this material is a candidate for expanding the capabilities of Si-based technology. In this study, we performed oxygen ion implantation into bulk SiC to produce SiC-on-insulator structures. We examined the microstructures and compositional distributions in implanted specimens using transmission electron microscopy and a scanning transmission electron microscope equipped with an energy-dispersive X-ray spectrometer (STEM-EDX).
Figures 1(a) and 2(a) show bright-field images of 6H-SiC implanted with 180 keV oxygen ions at 650 °C to fluences of 7xl017 and 1.4xl018 cm−2, respectively. Three regions with distinct image contrast are apparent in Figs. 1(a) and 2(a), as indicated by A, B, and C.
Nanoindentation in Tin/Nbn Multilayers and Thin Films Examined Using Transmission Electron Microscopy
Authors: Lloyd SJ , Pitchford JE , Molina-Aldareguia JM , Barber ZH , Blamire MG , Clegg WJ 
Published: July 2020

Abstract
Nanoindentation allows the hardness of thin coatings and synthetic multilayer structures to be measured, since indentation depths can be as little as a few 10s of nm. In combination with the cross-sectional transmission electron microscopy (TEM) analysis described here it is possible to observe the deformation structure under an indent, and potentially to understand deformation mechanisms on a nm scale in a wide variety of materials. Synthetic multilayers are a particularly interesting system to investigate. Variations in hardness with the multilayer compositional repeat distance (A) have been reported for several systems. The highest hardnesses, which are in excess of what a simple “rule of mixtures” would predict, occur in nitride multilayers at A ∼5nm. Here we present some preliminary results showing the deformation structure in both a monolithic NbN film and a TiN/NbN multilayer in which both components have the rQck salt structure with lattice parameters 0.424nm (TiN) and 0.439nm (NbN).
Heterogeneous Formation of Oriented Silicon Oxynitride on α-Si3N4 Seed Crystals : Habits And Radiation Stability
Authors: Carpenter RW , Braue W , Kim MJ 
Published: July 2020

Abstract
Lath-like silicon oxynitride crystals have often been observed in the microstructure of silicon nitride based ceramics after processing. They are usually located in glassy regions which are siliceous solidified sintering aid liquid, and usually contain a small (∼100nm) a-Si3N4 crystal. These nitride crystals are considered to be seeds, incompletely dissolved in the melt, that are heterogeneous nucleation sites for the oxynitride crystals. We present here the first observations of morphological and crystallographic habits between the seed nanocrystals and the host oxynitride laths.
Fig. 1 shows a typical oxynitride lath containing a nitride seed crystal. The lath is surrounded by glass and ß-Si3N4 particles, and a small cristobalite particle (a minor constituent). This microstructure is from an Si02-Si3N4 ceramic processed with Al2O3 sintering aid. The same oxynitride lath/seed structures were observed when other sintering aids (eg. Y2O3, MgO, ZrO2) were used, so they are independent of sintering aid.
In Situ Observation of Ferroelectric Domain Motion in BaTiO3
Authors: Krishnan A , Bisher ME , Treacy MMJ 
Published: July 2020

Abstract
Ferroelectrics are used in many applications such as non-volatile memory, infrared detectors, phased array radar and optical switches. While substantial progress has been made in the development of commercial ferroelectric devices, we still do not possess a good understanding of the fundamental processes in ferroelectrics. Trapped charge and oxygen vacancies are believed to strongly influence domain motion. In order to study these issues, we have designed an in situ TEM holder that can subject ferroelectric crystals to voltage, heat and UV irradiation.
Bulk BaTi03 crystals, grown by the Remeika method, were mechanically polished and thinned in hot ophosphoric acid. The resulting thin flakes were attached to copper rings with conductive carbon paint and electrical wires were glued to the copper rings, which act as electrodes. The sample was placed in the cradle of the in situ TEM holder and examined in a Hitachi H9000NAR TEM.
Analytical Electron Microscopy of Composite Interfaces
Authors: Kim Steven , P. Dravid Vinayak 
Published: July 2020

Abstract
The fiber/matrix interfaces play a critical role in the mechanical performance of fiber-reinforced ceramic-matrix composites (CMCs). In this vein, the placement of an interphase material between the fiber and matrix phases has received considerable attention. The main purpose of the interphase coating is to enhance toughness of the composite by influencing crack trajectories at the mechanically critical (weak) fiber/coating interface.
This interest in coated-fiber composites has been accompanied by the need for accurate microanalysis of the CMC systems, owing to issues of both morphological and chemical incompatibilities between the dissimilar fiber and coating materials. Consequently, microanalysis has been driven below the micrometer scale, into the length scale of nanometers. Thus, the examination of the fiber/coating interfaces in CMCs falls squarely into the realm of transmission electron microscope (TEM) and scanning transmission electron microscopy (STEM) analyses.
However, the success of TEM/STEM-based microanalysis of CMCs hinges critically on the quality of TEM specimen.