bluuebunny/crossref_metadata_2025_split huggingface dataset:
Convergent-beam electron diffraction at high spatial resolution
Authors: Steeds J W 
Published: June 2020

That the techniques of convergent beam electron diffraction (CBED) are now widely practised is evident, both from the way in which they feature in the sale of new transmission electron microscopes (TEMs) and from the frequency with which the results appear in the literature: new phases of high temperature superconductors is a case in point. The arrival of a new generation of TEMs operating with coherent sources at 200-300kV opens up a number of new possibilities.First, there is the possibility of quantitative work of very high accuracy. The small probe will essentially eliminate thickness or orientation averaging and this, together with efficient energy filtering by a doubly-dispersive electron energy loss spectrometer, will yield results of unsurpassed quality. The Bloch wave formulation of electron diffraction has proved itself an effective and efficient method of interpreting the data. The treatment of absorption in these calculations has recently been improved with the result that <100> HOLZ polarity determinations can now be performed on III-V and II-VI semiconductors.
Grain boundary segregation in metals
Authors: Briant C.L. 
Published: June 2020

Grain boundary segregation is the process by which solute elements in a material diffuse to the grain boundaries, become trapped there, and increase their local concentration at the boundary over that in the bulk. As a result of this process this local concentration of the segregant at the grain boundary can be many orders of magnitude greater than the bulk concentration of the segregant. The importance of this problem lies in the fact that grain boundary segregation can affect many material properties such as fracture, corrosion, and grain growth.One of the best ways to study grain boundary segregation is with Auger electron spectroscopy. This spectroscopy is an extremely surface sensitive technique. When it is used to study grain boundary segregation the sample must first be fractured intergranularly in the high vacuum spectrometer. This fracture surface is then the one that is analyzed. The development of scanning Auger spectrometers have allowed researchers to first image the fracture surface that is created and then to perform analyses on individual grain boundaries.
Measurement of segregation at interfaces by AEM
Authors: Garratt-Reed Anthony J. 
Published: June 2020

Many material properties are determined by the segregation (or lack of it!) of atoms of trace elements to boundaries, including, for example, the strength, electrical conductivity, dielectric constant, and diffusion properties. Many scientists are therefore interested in measurements of the segregation, and have found the field-emission scanning transmission electron microscope to be an invaluable tool.There are two cases to be differentiated. In the first, typified by sensitization in stainless steels, the width of the segregation or depletion zone is large compared with the diameter of the electron probe and the beam broadening. In the second, the reverse is true, the beam diameter and/or the beam broadening is large compared with the extent of the segregation. While the first case is certainly of interest, this paper will be concerned solely with the second.The earliest attempts at detecting grain boundary segregation by AEM were made by Doig et. al., studying tin segregation in iron alloys in a 100kV microscope with a tungsten-hairpin electron gun.
Annular dark-held images of crystals
Authors: Silcox John , Hillyard Sean , Loane Russell F. 
Published: June 2020

The demonstration of Z-contrast atom structure images and high spatial resolution using annular dark field STEM has drawn considerable interest. This approach is well suited for quantitative image and diffraction pattern acquisition. It has thus proven possible to use experimental data to validate calculations of convergent beam electron diffraction (CBED) patterns in silicon and ADF STEM images of (100) InP. Such simulations can then be extended, as reported here, to explore the dependence of images on factors such as thickness.Energy filtered CBED patterns over an angular range of over 150 mrads and covering a range of over four orders of magnitude in intensity from silicon were recorded with a VG HB501A STEM for thicknesses of 217Å, 326Å and 543Å. Simulation using a “frozen phonon” approximation successfully modeled this data provided an accurate phonon amplitude was used. A similar quantitative study for images has been carried out for (100) oriented InP.
Experiences with HPGe EDS detectors on a philips EM430 and a JEOL 6300F FESEM
Authors: Griffin Brendon J. , Johnson Andrew W.S. 
Published: June 2020

A turreted 10mm2 HPGe Link EDS detector has been mounted on a JEOL 6300F field emission SEM and the performance compared to that of a Si(Li) Link detector on a JEOL 6400 conventional SEM with identical geometry and construction.A second HPGe Link EDS detector has been mounted on a Philips EM430.The detector is 30 mms. sq.in area,with a type LZ5 ultra thin window and is mechanically configured to retract behind a gate valve and in addition, has a pneumatically operated shutter to provide a rapid protection from excessive electron and x-ray doses.Both detectors were shipped 'wet' from the factory and appeared to be contaminated by ice when initially tested on the columns. The FESEM detector was de-iced after two conditioning events and achieved an on-column resolution at Mn Kα of 115ev which matched the factory performance. Principal changes to spectra through the de-icing were improvement of resolution, decrease of dead time, reduction of oxygen Kα peak and improvement in copper Lα : Kα peak ratio. The EM430 detector has been more problematical.
Peak-to-background measurements on a 300-kV TEM/STEM
Authors: Zemyan S. M. , Williams D. B. 
Published: June 2020

As has been reported elsewhere, a thin evaporated Cr film can be used to monitor the x-ray peak to background ratio (P/B) in an analytical electron microscope. Presented here are the results of P/B measurements for the Cr Ka line on a Philips EM430 TEM/STEM, with Link Si(Li) and intrinsic Ge (IG) x-ray detectors. The goal of the study was to determine the best conditions for x-ray microanalysis.We used the Fiori P/B definition, in which P/B is the ratio of the total peak integral to the average background in a 10 eV channel beneath the peak. Peak and background integrals were determined by the window method, using a peak window from 5.0 to 5.7 keV about Cr Kα, and background windows from 4.1 to 4.8 keV and 6.3 to 7.0 keV.
Elemental analysis of telatively thick specimens by EELS
Authors: Egerton R.F. , Cheng S.C. 
Published: June 2020

Core-loss spectra of thicker specimens are strongly influenced by plural scattering. Plural inelastic events increase the background Ibunderneath an ionization edge by an amount dependent on t/λ, t being the specimen thickness and λ the total-inelastic mean free path. However, plural scattering also contributes to the integral core-loss signal Ic. In fact, if the latter were integrated over a sufficiently large energy window Δ, the signal/background ratio (SBR=IC/Ib) might be expected to be independent of t.Figure 1 shows K-edge signal/background ratios for elemental carbon and silicon, presented as measured data points (for a collection semi-angle of l0mrad, 120keV incident energy and Δ=100eV) and as solid curves calculated by convolving a power-law edge profile with a delta-function approximation of the low-loss region. For silicon, SBR falls off more slowly with increasing t/λ, as expected from its higher edge energy. This trend is confirmed by measurements on amorphous silicon dioxide depicted in Fig.2, which shows the signal/background ratios of the oxygen and silicon K-edges as a function of thickness.
Effects of chamber pressure and accelerating voltage on X-RAY resolution in the ESEM
Authors: Griffin Brendon J. 
Published: June 2020

Chamber pressure, accelerating voltage and working distance have been shown to control the relative diameter of the scattered skirt of the primary electron beam at the specimen surface in the ESEM. Inital x-ray studies indicate that at 3 torr, 30 kV and a WD=15mm, 45% of the beam comes from beyond 25 μm of the incidence point and 4% from beyond 1.5mm. At 5 torr 66% of the beam is scattered beyond 25 μm2. No specific data was available on the spatial resolution of x rays and this study aimed to improve that situation. The results also form the basis for establishing a mechanism for and defining the potential limits of quantitative EDS microanalysis in the ESEM.The negative viewing angle of the EDS x-ray detector in the current ESEM (model E-3) requires at least a 15 degree tilt on a flat sample for microanalysis. This geometry places a narrow limit on the working distance range that can be used, due to the collimation of the detector, thereby effectively eliminating working distance as a variable in x-ray microanalysis.
Analytical characterization of dilute cxsi1-x alloys grown by molecular beam epitaxy on si(100)
Authors: Posthill J.B. , Malta D.P. , Humphreys T.P. , Hattangady S.V. , Fountain G.G. , Rudder R.A. , Markunas R.J. 
Published: June 2020

As discussed elsewhere recently, metastable CxSi1-x epitaxial alloys on Si(100) have been fabricated which may eventually find utility in Si bipolar or FET device technology where a heterobarrier or specific strain control would be desirable. Research on the metastable binary CxSi1-x system is also the logical first step toward development of the metastable ternary CxSiyGez system where the possibility of independently altering lattice parameter, strain, and band gap exists. Since the initial report of the epitaxial growth of dilute CxSi1-x alloys on Si(l00) by remote plasma-enhanced chemical vapor deposition (RPECVD), there has also been progress in this field using solid source molecular beam epitaxy (MBE); particularly in the growth of strained layer Si/CxSi1-x/Si superlattices. We report on MBE growth and characterization of CxSi1-x epitaxial alloys grown to a substantial thickness.An MBE chamber equipped with independent e-beam evaporation of Si and graphite and a base pressure of 5×10−10 Torr was used for growth.
TEM studies of (ZnSe/FeSe) superlattices
Authors: Park K. , Salamanca-Riba L. , Jonker B. T. 
Published: June 2020

Diluted magnetic semiconductors (DMS) are of considerable interest in the area of heterostructures and superlattices because the lattice parameter, energy gap, and effective mass can be “tuned” in a controlled fashion by varying the composition. This tunability has been exploited in the fabrication of DMS superlattices. Since the superlattices can be grown with a wide range of choices of materials, there is a great variety of possible applications requiring magneto-optical properties. However, the lattice mismatch between the constituent layers in the superlattice and between the superlattice and the substrate makes it difficult to grow high quality superlattices.Superlattices of (11.4 Å FeSe/34.0 Å ZnSe)12 (sample A) and (20.0 Å FeSe/45.3 Å ZnSe)6 (sample B) were grown on (001) GaAs substrates using MBE. Sample A was grown on a ZnSe buffer layer with a thickness of 500 Å on a (001) GaAs substrate, while sample B was grown directly on a GaAs substrate. TEM samples were prepared by mechanical grinding, dimple grinding, and ion-milling (3.0 keV Ar+ ions and 1 mA current) at liquid nitrogen temperature.
Formation of defects in implanted hipox-structures
Authors: Pegler Peter , David Theodore N. , Pan Ming 
Published: June 2020

High-pressure oxidation of silicon (HIPOX) is one of various techniques used for electrical-isolation of semiconductor-devices on silicon substrates. Other techniques have included local-oxidation of silicon (LOCOS), poly-buffered LOCOS, deep-trench isolation and separation of silicon by implanted oxygen (SIMOX). Reliable use of HIPOX for device-isolation requires an understanding of the behavior of the materials and structures being used and their interactions under different processing conditions. The effect of HIPOX-related stresses in the structures is of interest because structuraldefects, if formed, could electrically degrade devices.This investigation was performed to study the origin and behavior of defects in recessed HIPOX (RHIPOX) structures. The structures were exposed to a boron implant. Samples consisted of (i) RHlPOX'ed strip exposed to a boron implant, (ii) recessed strip prior to HIPOX, but exposed to a boron implant, (iii) test-pad prior to HIPOX, (iv) HIPOX'ed region away from R-HIPOX edge. Cross-section TEM specimens were prepared in the <110> substrate-geometry.
Microstructure of capacitor-structures exhibiting varying charge-to-breakdown
Authors: Pan Ming , Gong Sheng , David Theodore N. 
Published: June 2020

The quality of oxide/silicon structures is of interest because of extensive application in capacitors and MOSFETs. Various factors can influence electrical breakdown of such structures. Breakdown can occur by enhancement of electric fields at the injecting interface due to the presence of trapped positive charges (holes), due to mobile ions, or due to interface roughness and oxide nonuniformities. In the present study, transmission electron microscopy (TEM) was used to characterize oxide/ substrate and oxide/ poly-Si interfaces in poly-Si/ oxide/ substrate-silicon structures. Electrical measurements had shown varying values of charge-to-breakdown (Qbd) for different but equivalent structures on a wafer. The purpose of this study was to investigate differences in microstructure and interfaces among the different structures.Capacitors were fabricated on (100) p-type silicon with a 1.6μm p-type epitactic layer. A 4E12 cm−2 phosphorus implant was used for Nwell capacitors and a 3.5E12 cm− boron implant was used for Psub capacitors. Silicon-dioxide (∼175 Å) was grown on top of implanted substrates. Phosphorus-doped polysilicon (5E12 cm−2 phosphorus) was then deposited on top the oxide layers to form field plates.
Auger electron spectroscopy at nanometer resolution
Authors: Hembree Gary G. 
Published: June 2020

Auger electron spectroscopy (AES) is a surface sensitive microanalytical technique. Auger electrons are only detected from the top few atomic layers due to their very small inelastic mean free paths. The lateral spatial resolution of AES of thin samples is dominated by the excitation beam profile. Thin samples are defined as having a thickness which is much smaller than the back-scattered electron range at the incident beam energy. Utilizing high current density nanometer-sized probes available in field emission gun STEMs, AES signals extracted from sample regions as small as a few atoms should be detectable. However, the extremely low production efficiency for Auger electrons makes this atomic scale resolution difficult to achieve in practice.We have achieved nanometer spatial resolution AES in our modified Vacuum Generators HB-501S. In this instrument secondary electrons emitted from either surface of the sample are efficiently collected using the collimating properties of the objective lens field, a sample bias potential and additional solenoidal focusing coils.
Recent improvements of the capabilities of multichannel Raman microprobing
Authors: Delhaye M. , Barbillat J. , Dhamelincourt P. ,   DILOR S.A. (France)
Published: June 2020

Raman microprobing techniques, pioneered nearly 20 years ago, have demonstrated their potential in a large variety of application domains. From the origin up to now, a fruitflul collaboration was established between our laboratory at CNRS-University of Lille - and the industrial team of engineers and scientists brought together by E. DA SILVA at DILOR. A series of innovative progresses, inventions and developments was undoubtedly the consequence of this close cooperation, resulting from a careful analysis of the requirements of spectroscopists and analysts in fundamental or applied research, together with a critical appreciation of the various approaches offered by new technologies.The choice of dispersion, resolution and spectral coverage of conventional optical spectrometers are physically limited by the design parameters (i.e. grating groove spacing, diffraction angle, focal length and detector array dimensions). However, it would be often desirable, in order to select the best compromise of Resonance Raman and fluorescence background, to first examine quickly at low dispersion the whole spectrum from near UV to near IR, in the next step to cover at once the full vibrational range 0-3500 cm-1 with the choosen exciting radiation for a rapid survey of an unknown specimen, and finally to focus the spectral analysis in a narrow spectral domain at high resolution. Such a procedure is often not feasible with a single instrument.
Resolution in scanning IR infrared microprobe analysis
Authors: Reffner John A. 
Published: June 2020

The scanning infrared microprobe was critically analyzed in terms of both its imaging and its compositional resolution. Fundamentally, resolution is the act or process of breaking something into its constituent parts or elements. Separating parts of the image is the point-to-point resolution of an imaging system. In interferometry and profilometry, the separation of heights is an additional criterion for resolution. Microprobe analysis has extended-resolution requirements that consist of the break-up of the sample's image into its chemical parts.In scanning infrared microprobe analysis, resolution has several meanings: resolution of the visual image, the spatial resolution of the analyzed domain, and the resolution of the chemistry within the analyzed sample. The point-to-point resolution of the visual image is limited by diffraction, as in all classical microscopy. The resolution, in terms of the area defined for spectral analysis, is limited by both diffraction effects and spectrometer sensitivity. The chemical resolution of the SIRM is compared with other microprobe techniques.
The use of IR microspectroscopy in the analysis of etowah textiles: evidence of dye use and pseud0m0rph formation
Authors: Martoglio Pamela A. , Jakes K. A. , Katon J. E. 
Published: June 2020

Previously, our laboratory reported the analysis of archaeological textiles from the Paracas Necropolis (400 BC - 400 AD) in Peru. The study has been expanded to include textile fragments from the Etowah Mound C located in Northwest Georgia. These fragments have been dated approximately 1200 AD. Samples were removed from four textile fragments, catalog numbers EMC 640, EMC 842, EMO A842, and an unnumbered copper covered ear disk. These textiles have been described in detail in other publications. Infrared and visible spectra were obtained from fibers removed from each of these fragments, as well as spectra of three dye plant extracts (Galium corymbosium, Galium aparine, Rubia tinctoria or cordifolia) and spectra of alum mordanted wool dyed with those extracts.IR spectra are obtained on an Analect AQS-20M IR microspectrometer system with an MCT narrow band detector. Single fibers are prepared for analysis by flattening with a metal probe and transferring to a 1 mm-thick KC1 plate. Typical sample areas range from 30 to 50 μm in diameter.
Pressure tuning IR and micro-raman spectra of solid zeiseߣs salt, kp[pt(η-C2H4)Cl4], and the related dimer, [Pt(η-C2H4)Cl2]2
Authors: Baldwin Jean , Butler Ian S. , Gilson Denis F. R. 
Published: June 2020

Pressure-tuning vibrational spectroscopy using diamond-anvil cells is now well established as a useful technique for investigating the phase-transition behavior of inorganic and organic solids. Much of our recent research has been focused on organotransition metal compounds, especially metal carbonyls. The pressure dependences (dv/dP) of the v(CO) modes provide important information on the extent of #- backbonding between the metals and the carbonyl groups. We have now extended these high-presure studies to other #-acceptor ligands, including olefins. We report here the results of a high-pressure IR and micro-Raman spectroscopic investigation of the ethylene complexes, K[Pt(η-C2H4)C13] (Zeise's salt) and the related dimeric species, [Pt(η-C2H4)C12]2- We were interested in examining the effect of high pressures on the Dewar-Chatt-Ducanson σ-/π-bonding description of the platinum-ethylene bonding. There is still considerable controversy over the relative σ- and π-contributions to the overall bonding in such metal-olefin complexes.Micro-Raman spectra of solid K[Pt(η-C2H4)C13] were obtained at room temperature for the low-energy region (500-180 cm-1) at varying pressures up to 33 kbar with the aid of a diamond-anvil cell. Similarly, pressure-tuning IR spectra were measured for Zeise's salt (3080-480 cm-1; 32 kbar) and Zeise's dimer (4000-480 cm-1; 28 kbar) up to the pressures indicated.
Use of Raman microprobe for study of inhomogeneity of the high-transition-temperature superconductors
Authors: Ishitani Akira , Katagiri Gen , Ishida Hideyuki 
Published: June 2020

Study of inhomogeneity of high Tc superconductors is becoming more important when real application of the exciting materials has started. Raman microprobe can be one of the important techniques for the characterization because of the capability of giving detailed structural information with μm spatial resolution. Preliminary study on YBa2Cu3Oz(YBCO) will be reported.Qualitative analysis of impurity phases by Raman spectroscopy is effective, because YBCO has relatively small scattering capability whereas common impurities like Y2BaCuO5 and BaCuO2 show intense Raman scattering as indicated in Figure 1. A fused YBCO with Y2BaCuO5 intentionally brought in to enhance the pinning effect shows clearly the characteristic Y2BaCuO5 spectrum overlapped with the host material as in Figure 2.Study of crystalline orientation of polycrystal1ine YBCO is important for practical application as an electric wire. The average orientation can be obtained by Xray and neutron diffraction techniques. Raman microprobe gives orientation of a minute crystal of the size of μm range. Figure 3 gives an example.
Energy-filtered imaging in biological intermediate voltage TEM
Authors: Gubbens A.J. , Krivanek O.L. 
Published: June 2020

In biological specimens of 150 nm and greater, inelastic scattering typically surpasses elastic scattering in magnitude. Because of the chromatic aberration of the objective lens of a TEM, the inelastically scattered electrons are focused differently, resulting in a loss of contrast in an ordinary TEM. With energy filtering, however, the inelastically scattered electrons can be prevented from contributing to the image, resulting in substantial recovery of contrast. In very thick specimens (1-5 μm), an energy filter can be used to select electrons of a particular energy loss, and an image with usable contrast can be formed. Further, by imaging only with electrons that have experienced characteristic energy losses, information can be obtained about the spatial distribution of various elements in the sample.Because of presently available instrumentation, energy filtered biological TEM has so far only been performed with TEMs of primary energies of 120 keV and lower. In this paper, we demonstrate the feasibilty of obtaining interesting biological information with a newly developed imaging filter designed for operation at up to 400 kV.