bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization Of SiOx Smoke Particles by Electron Energy Loss Spectroscopy and Energy-Filtering Imaging
Authors: Dufner DC , Danczyk S , Wooldridge M 
Published: July 2020

Abstract
Combustion synthesis has led to many advances in materials science, in part via the synthesis of powders consisting of particles of nanometer dimensions. Particle morphology is a key concern regarding the powders produced, but also of comparable importance is particle composition. Electron energy loss spectroscopy (EELS) and energy-filtering imaging (EFI) can be used to interrogate the gas-phase combustion synthesis environment for elemental particle composition information. Once established, this diagnostic approach can be used to address control of particle composition and other issues associated with particle formation and growth in flames. The evolution of the particle morphology in a laboratory scale combustion synthesis facility can be examined by passing TEM grids directly through the combustion synthesis flame at various heights above the burner surface, as shown in Fig. la. For the current work, SiOx particle samples are obtained from a SilL/^/FL/Ar flame using a rapid probe insertion technique.
EELS Characterization of Silicon Oxycarbide Glasses
Authors: Cheng SC , Colombo P , Pantano CG 
Published: July 2020

Abstract
Anionic modification of silicate-based glasses with carbon has recently attracted the attention of many research groups due to the beneficial effect on mechanical properties and both thermal and chemical stability. These carbon containing glasses, termed silicon oxycarbide glasses, can be synthesized from various organically modified silica gels or from preceramic polymers after a pyrolysis process in an inert atmosphere. The oxycarbide network is often mixed with a free carbon phase, and so the local environment around C atoms exhibits a complex distribution. In the ideal silicon oxycarbide phase, carbon atoms would be present only in carbidic units (forming only Si-C bonds). The carbon phases and the chemical bonding in the silicon oxycarbide have been investigated by high resolution electron microscopy (HREM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR). Electron Energy Loss Spectroscopy (EELS) is an important analytical technique that can be used to further characterize the local chemistry and electronic structure of these glasses.
Threshold Energy Effects in Secondary Electron Emission
Authors: Howie A 
Published: July 2020

Abstract
The work function ϕ, the bandgap Eg, the threshold energy level Et, for the inelastic scattering of excited electrons and the threshold energy transfer Ed for the onset of structural ionisation damage are clearly of major significance in various actively developing forms of hot carrier imaging. Two exciting examples here are the ability to image small and dynamic local changes in work function by PEEM and as well as mapping the variations in electronic structure between p and n-type regions of a semiconductor by SE imaging in the SEM. More recently still there have been indications that the SE signal in the ESEM might be sensitive to local changes in bandgap and suggestions that it might be even possible to image spatial variations in pH. It is increasingly clear that if these attractive opportunities are to be efficiently explored and developed, systematic and preferably quantitative observations are needed. Such work requires specimens whose atomic and electronic structure is either fully known beforehand or can be deduced from other signals available in a situation where the physical processes in the microscope are well understood.
Valence Electron EELS Spectroscopy on Nanoparticle Surfaces
Authors: Colliex C , Suenaga K , Kociak M , Stephan O 
Published: July 2020

Abstract
A series of recent experiments, using electron as well as photon probes [1-3], have attracted considerable interest on the importance of surface plasmon modes in nanostructured media such as nanospheres, nanotubes, nanowires, nanopores or nanoholes.
The basic principle for STEM operation had early been recognized to be well suited to the investigation of cases where non penetrating electrons propagate at a given impact parameter from an external surface (along "aloof7 trajectories, using a terminology proposed by Warmack et al. [4]). One of the most spectacular effect is that signals attributed to the excitation of-surface plasmon modes could be detected in vacuum at distances as large as a few tens of nanometers from the outside surface of a specimen, see for instance [5] for the planar geometry and [6], for the spherical one. Most interpretations accounting for the spatial dependence of EELS spectra in the "aloof geometries, rely on models using the bulk dielectric coefficients of the material to describe the induced charges and polarization responsible for the specimen electric field acting on the probe electron and consequently for the measured energy loss.
Microscopy of Metal Oxide Surfaces
Authors: Castell MR , Dudarev SL , Muggelberg C , Briggs GAD , Sutton AP , Goddard DT 
Published: July 2020

Abstract
Widespread application of metal oxides in catalysis, gas sensing, and as substrates for thin film growth has stimulated a strong interest in the atomic and electronic surface structure of these materials. The electronic structure of many metal oxide surfaces is characterised, and complicated from the theoretical modelling point of view, by the presence of strong on-site Coulomb repulsion (strong correlations) between valence electrons localised on the metal ions. Additionally, experimental studies have to deal with the difficulties associated with the electrically insulating nature of many of these oxides. We have overcome these problems through the development of novel experimental and theoretical techniques capable of providing structural and electronic information about strongly correlated insulating metal oxide surfaces.
The surfaces of NiO and CoO were investigated through elevated temperature scanning tunnelling microscopy (STM) thereby overcoming problems of low electrical conductivity of the samples.We show atomically resolved elevated temperature STM images of (001) cobalt and nickel monoxide surfaces obtained under similar conditions which show an order of magnitude difference in the atomic corrugation heights.
Designer Nanostructures Of Catalysts in the Environmental-HREM
Authors: L. Gai Pratibha 
Published: July 2020

Abstract
Major advances in the field of in situ environmental high resolution electron microscopy (EHREM) probe selective oxidation catalysis directly on the atomic scale. Dynamic gas-solid surface interactions are studied in real-time and under realistic reaction conditions to unravel atomic level insights into active sites and structure-property relationships in vital chemical and technological processes [1-3]. The recent developments include a pioneering approach with the controlled environmental cell (ECELL) facilities permanently mounted inside the EHREM [2]. Accessories have been added for simultaneous structural and compositional analyses of the reactor contents in real-time, and using atomic resolution imaging with transmission electron diffraction and parallel electron energy loss spectroscopy (PEELS). We are now developing innovative experimental methods that include very high temperature studies and combining in the same instrument facilities for both EHREM and environmental-SEM (ESEM), (EHREM-ESEM), with attractive possibilities for studying the science of selective oxidation catalysis.
Alkane Catalysis, Chlorofluorocarbons and Nanotubes:
In the domain of transition metal based oxides, discoveries of fundamental mechanisms underlying selective catalyzation have come from EHREM studies.
Stacking-Fault Fringes
Authors: Barry Carter C , Medlin DL , Cohen Dov , Campbell Geoffrey 
Published: July 2020

Abstract
Crystalline interfaces associated with lattice translations such as stacking-faults (SFs) and twin boundaries may be characterized in the transmission electron microscope (TEM) by oscillatory fringe contrast known as SF, or rigid-body-translation, fringes. Such fringe contrast is usually obtained using weak-beam bright-field (BF) or dark-field (DF) conditions with ideally only one reflection, g, excited. The nature of the SF contrast has been explained by dynamical theory of electron diffraction in terms of the Howie-Whelan equations [1]. The fringe contrast arises from an interference caused by a phase shift the diffracted electron beams, undergo upon propagating across the interface. The phase shift, α, is proportional to the projection of the translation vector, R, onto the diffraction vector, g (i.e. α # g.R). The direction of the translation state can be determined explicitly from the SF contrast in a manner analogous to the analysis of dislocation Burgers vector.
An analysis of SF fringes with respect to diffraction theory permits the magnitude of the lattice translation to be evaluated in experimental images.
In-Situ HREM of A Surface Reconstruction of Si Surface With Molten Al at High Temperatures
Authors: Tsukimoto S , Arai S , Miyai H , Saka H 
Published: July 2020

Abstract
Introduction
The morphology of Si surface has much effect on physical and chemical properties of the surface. It is well known that the structure of Si surface can be modified by deposition of metals, and extensive studies have been carried out on the modified surface structures of Si. These studies were carried out on clean surfaces of Si in an ultra-high vacuum (UHV). However recently, it has been shown by Kamino et al.[l] that molten Au atoms remove a surface amorphous layer on the Si surface, making the surface clean even in a non ultra-high vacuum. The present study is an extension to the previous one (Kamino et al.) and Si surfaces modified by-molten Al atoms in a conventional vacuum were observed by means of TEM.
Experimental
The specimen used in this study was a mixture of pure Al particles and Si particles, the latter being prepared by crushing a Si single crystal into pieces.
Novel Xerogel Catalyst Materials for Hydrogenation Reactions and the Role of Atomic Scale Interfaces
Authors: Gai PL , Kourtakis K , Dindi H , Ziemecki S 
Published: July 2020

Abstract
We are developing a new family of heterogeneous catalysts for hydrogenation catalysis. Catalyst synthesis is accomplished using colloidal polymerization chemistry which produce high surface area xerogel catalysts. These xerogels have been synthesized by one-step sol gel chemistry. These catalysts contain ruthenium and modifiers such as gold occluded or incorporated in a titanium oxide matrix. The materials, especially the modified systems exhibit favorable performance in microreactor evaluations for hydrogenation reactions and exhibit high activities. Nanostructural studies have revealed that the materials contain dispersed catalyst clusters which are desirable microstructures for the catalysis since the majority of the atoms are exposed to catalysis and are potentially active sites.
The composition and atomic structure of the xerogel catalysts containing ruthenium and other metals have been examined using our in-house developments of environmental high resolution electron microscopy (EHREM) the atomic scale [1-3] and low voltage high resolution SEM (LVSEM)[4] methods.
Electron Microscopy of Solid- Liquid Interfaces: HREM Observation and EELS Analysis
Authors: Saka H , Arai S , Tsukimoto S , Miyai H , Konno M , Kamino T 
Published: July 2020

Abstract
A solid-liquid interface in the Al–Si system has been observed at near-atomic resolution by in-situ heating experiments inside transmission electron microscopes. Chemical mapping was also attempt to detect distribution of constituent atoms near a solid–hquid interface.
Mixtures of Al particles and Si particles, the diameter of which ranged from 200nm to 800nm, were mounted on a specimen–heating holder developed by Kamino and Saka and examined in a Hitachi H–9000NAR and a Hitachi HF–2000 electron microscope, operated at accelerating voltages of 300 and 200kV, respectively. Heating these specimens above the melting point of pure Al inside the microscopes resulted in the melting of the Al particles. The liquid Al reacted with nearby Si, leading to the formation of Al–Si alloy phase. An interface between solid Si and Al–Si alloy hquid and also an interface between solid Al and Al–Si alloy liquid were observed. The dynamical behaviour was recorded continuously using TV–VTR systems. The distribution of Al and Si was visualized using a Gatan imaging filter GIF analyzer.
High Angular Resolution Measurements Of K Shell X-Ray Emission Created by Electron Channeling in the Analytical Electron Microscope
Authors: J. Zaluzec Nestor 
Published: July 2020

Abstract
Since the original observations by Duncumb in 1962, a number of studies have been conducted on the effects of electron channel on characteristic x-ray emission and microanalysis. Most of the recent studies have concentrated upon using the phenomenon to perform site specific distributions of impurity elements in ordered compounds using the ALCHEMI methodology. Very few studies have attempted to accurately measure the effect as a function of orientation and compare these results to theory. In this study, two dimensional high angular resolution studies of channeling enhance x-ray emission were performed and herein the results are compared to theoretical calculations of Allen etal.
All experimental measurements presented here were conducted on a Philips EM 420T analytical electron microscope. The instrument was operated in the TEM mode, at 120 kV using an LaB6 electron source. The characteristic x-ray emission was measured using an EDAX ultra thin window Si(Li) detector having a FWHM of ∼ 145 eV at Mn Kα.
Field Emission Characteristics of Single Nano-Tips of Amorphous Carbon Grown on Tungsten Mini-Spheres
Authors: Edgcombe C , Valdrè U 
Published: July 2020

Abstract
Introduction
We report here results additional to those presented earlier on single amorphous carbon nano-tips grown by carbon contamination on substrates of well-defined geometry in a scanning electron microscope (SEM). This method offers beneficial accuracy in controlling the properties of the nanoemitters such as length, aspect ratio and positioning on the given substrate.
The work function, emission field, current density, emitting area, solid angle of emission, energy distribution and short and long term stability of these emitters are all of interest. Since the literature does not provide, as far as we know, the work function of contamination-grown amorphous carbon, its value must be determined experimentally, in our case through Fowler-Nordheim (F-N) plots. This quantity and others can be derived once the electric field F at the emitting surface is known. Since the geometry of our emitters is reasonably well known from the fabrication procedure and subsequent electron microscopy, it is possible to find a satisfactory value for F by computation.
High Resolution Measurements of Two Dimensional Dopant Diffusion in Silicon
Authors: Spinella Corrado 
Published: July 2020

Abstract
The development of the very large and ultra large scale integrated technology technology is based on the shrinkage of the lateral dimensions of semiconductors devices to a sub-micron level. Under these conditions the precise control of the total amount of dopant atoms dissolved in the silicon substrate, and of their depth and lateral distribution, become crucial requirements. One of the most promising device characterization technique is that based on transmission electron microscopy (TEM) analysis. Indeed, by means of TEM observations the device morphology can be imaged with a spatial resolution of the order of 0.1 — 0.3 nm; and, after an appropriate sample preparation method, based on selective chemical etch of doped silicon regions, the 2D dopant concentration profiles can be delineated with a resolution of the order of 5nm.
The chemical solution used for this aim consists of a mixture of both nitric and hydrofluoric acid.
In-Situ TEM Studies of the Interaction Between Dislocations in SiGe Heterostructures
Authors: Stach EA , Hull R , Tromp RM , Ross FM , Reuter MC , Bean JC 
Published: July 2020

Abstract
The rate of heteroepitaxial strain relaxation via misfit dislocation introduction is strongly limited by the kinetics of dislocation nucleation, propagation and interaction. Here we describe real-time observations of the interaction between moving threading dislocations and pre-existing interfacial misfit dislocations using in-situ transmission electron microscopy. This was accomplished both during in-situ observations of the heteroepitaxial growth process using a modified ultrahigh vacuum TEM (UHV-TEM) equipped with chemical vapor deposition capabilities, as well as during in-situ anneals of metastable structures grown by molecular beam epitaxy.
In Figure 1, we present our UHV-TEM observations of the epilayer thicknesses and compositions at which dislocation interactions result in blocking of the propagating threading segment, and compare these with the theoretical predictions of Freund and those of Schwarz and Tersoff. Our results show that dislocation blocking can significantly affect the overall rate of strain relaxation in these structures. This is important, as blocked threading segments introduce undesired band gap states into electronic devices and can act as easy diffusion paths for impurities and dopants.
Lighting With GaN: How Can HREM Help To Understand The Iii-Nitride System?
Authors: Kisielowski C , Nelson EC , Song C 
Published: July 2020

Abstract
Nowadays, High Resolution Electron Microscopes are capable to resolve structures on a scale below 100 pm. They can be equipped for Electron Holography in order to detect electric / magnetic fields and for chemical analyses (Electron Energy Loss Spectroscopy & Energy Dispersed X-ray's) that can be performed with a lateral resolution of 0.5 to 1 nm [1]. With the aid of computer sciences it became also possible to quantify local strain. We utilize Philips CM200 and CM300 field emission instruments with attached image filters, the JEOL Atomic Resolution Microscope and specialized software [2] to perform these tasks. On the other hand, a recent highlight in materials sciences is the development a GaN technology that is driven by a fast trial and error approach and aims to revolutionize lighting [3]. It was unavoidable that basic materials properties of the nano-structured thin films are barely understood because of the rapid progress [4].
Detection of Interstitial Molecules in Wide Band Gap Materials Using Cathodoluminescence Microanalysis
Authors: Stevens Kalceff MA 
Published: July 2020

Abstract
Cathodoluminescence (CL) microanalysis (spectroscopy and microscopy) enables both pre-existing and irradiation induced defects in the bulk and surface defect structure of wide band gap materials (i.e. semiconductors and insulators) to be monitored and characterized with high spatial resolution and sensitivity. The local micro-volume of specimen may be selected for investigation by varying the electron beam parameters. CL micro analytical techniques allow the in situ monitoring of electron irradiation induced defects and the investigation of irradiation induced electromigration of mobile charged defect species. Irradiation can result in the formation of defects and /or the transformation of existing defect precursors. CL emissions from a material are usually associated with native and impurity defects of the host lattice, however in special cases CL microanalysis can provide direct or indirect evidence for the presence of interstitial molecular species in a material. Atomic displacements from the normal bonding (i.e. defect free) sites induced by an electron beam can result from either knock-on, or radiolytic processes, depending on the incident electron beam energy.
Horizontal Defects Parallel to the Interface in GaN Pyramids
Authors: Mao Zhigang , McKernan Stuart , Barry Carte C , Yang Wei , A. McPherson Scott 
Published: July 2020

Abstract
The performance of III-V nitride-based microelectronic and optoelectronic devices relates directly to the micro structure of these materials. Selective lateral overgrowth has been exploited to produce GaN heteroepitaxial films with low defect density [1]. Si is a promising substrate due to its low cost, large size, and the potential for the intergration of GaN-based optoelectronic devices with Si-based electronics. It is also possible to produce high-quality GaN material for devices using lateral overgrowth on a Si substrate [2]. At present, only limited information on the defect structure in GaN heteroepitaxial films grown by selective lateral growth is available, especially those grown on Si substrate. Recent work [3] on GaN pyramids grown on (111) Si substrates by this method has shown that in the center, or core, of the GaN pyramid (at and above the window area) dislocations thread through the pyramid nearly perpendicular to the substrate surface and the dislocation density is quite high.
Weak-Beam Thickness-Fringe Contrast Analysis of Defects in GaN Pyramids
Authors: Mao Zhigang , McKeraan Stuart , Barry Carter C , Yang Wei , A. McPherson Scott 
Published: July 2020

Abstract
The possible dislocations and slip systems in the wurtzite structure are the same as in hcp structure [1]. The Burgers vectors of these dislocations are . The dislocations can lie on either the (0001) basal plane or prism planes. The dislocations lie on pyramidal planes. TEM studies have revealed that there are predominately three types of dislocations in a wurtzite GaN epilayer which has not been grown by selective overgrowth (e. g. [2, 3]). The majority of the dislocations are threading dislocations with Burgers vector which appear randomly in the epilayer, they result from the growth errors during the growth process. The other two types of dislocation are halflpops with a [0001] or Burgers vector. The [0001] dislocation half-loop lies on the prism plane and the dislocation half-loop lies on the (0001) basal plane which usually appears near the epilayer/substrate interface.
Chemical Characterization of Semiconductor Defects and Particles on the Wafer Surface by Multiple Microanalysis Techniques
Authors: Uritsky YS , Conti G , Brundle CR , Savoy R , Kinney PD 
Published: July 2020

Abstract
Development of future semiconductor processes and improving existing ones requires a strong capability to identify and eliminate the sources of particle defects. The current industry approach for accomplishing this task is to analyze the particles on the wafer surface. The most commonly used technique for this purpose is SEM with EDX (SEM/EDX). This approach provides information about defect chemistry and morphology, which in turn provides a direct path to the reevaluation of processes and hardware parts needed to determine the root cause of a problem. However, the SEM/EDX has three fundamental limitations: (a) it is a large volume technique and therefore, the sensitivity can be insufficient for sub micron particles and thin patches; (b) there is no chemical bonding information due to poor energy resolution; (c) charging problem for dielectrics. In some cases there is a need to use other techniques to support or substitute the EDX results.