Ordering In Zn0.5Fe0.5Se Epilayers Grown on InP Substrates by Molecular Beam Epitaxy

1991 ◽  
Vol 231 ◽  
Author(s):  
L. Salamanca Riba ◽  
K. Park ◽  
B. T. Jonker
Keyword(s):  
High Resolution ◽  
Ordered Structure ◽  
Cross Sectional ◽  
Zinc Blende ◽  
Transmission Electron ◽  
Lattice Images ◽  
High Resolution Images ◽  
Diffraction Patterns ◽  
Inp Substrates ◽  
Image Simulations

AbstractWe have observed an ordered structure in Zn0.5Fe0.5Se epilayers grown on (001) InP substrates using transmission electron microscopy. The ordered structure of Zn0.5Fe0.5Se has Fe atoms occupying the (0,0,0) and (½, ½, 0) sites and Zn atoms occupying the (0, ½, ½) and (½, 0, ½) sites in the zinc-blende unit cell. Ordering is observed in both electron diffraction patterns and cross-sectional high-resolution lattice images along the < 100 > and < 110 > directions. This ordered structure consists of alternating ZnSe and FeSe monolayers along the < 100 > and < 110 > directions. Computer image simulations of the high-resolution images under various thicknesses, and defocusing conditions have been obtained and are compared with those obtained experimentally.

Ordered Structures of Zn1−xFexSe Epilayers Grown on InP and GaAs Substrates

1993 ◽  
Vol 312 ◽  
Author(s):  
K. Park ◽  
H.- Y. Wei ◽  
L. Salamanca-Riba ◽  
B. T. Jonker
Keyword(s):  
Lattice Mismatch ◽  
Misfit Strain ◽  
Growth Direction ◽  
Ordered Structure ◽  
Cross Sectional ◽  
Ordered Structures ◽  
Gaas Substrates ◽  
Lattice Images ◽  
Diffraction Patterns ◽  
Inp Substrates

AbstractWe present evidence for two types of ordered structures, CuAu-I and CuPt, in Zn1−xFexSe (x≈ 0.4) epilayers grown by molecular beam epitaxy. These ordered structures are observed in both electron diffraction patterns and cross-sectional high-resolution lattice images. The CuAu-I ordered structure occurs in Zn1−xFexSe epilayers grown on (001) InP substrates, while the CuPt-type occurs in epilayers grown on (001) GaAs substrates. The ordered structure of Zn1−xFexSe grown on InP substrates consists of alternating ZnSe and FeSe layers along the [001] growth direction and the [110] direction. In contrast, the ordered structure of Zn1−xFexSe grown on GaAs substrates consists of alternating ZnSe and FeSe layers along the < 111 > directions. We have also investigated the role of the misfit strain associated with the lattice mismatch between the epilayers and the substrates on the type of ordered structure.

TEM Evaluation of CuAu-I Type Ordered Structures in MBE grown Ingaas Crystals on (110) Inp Substrates

1990 ◽  
Vol 209 ◽  
Author(s):  
O. Ueda ◽  
Y. Nakata ◽  
T. Nakamura ◽  
T. Fujii
Keyword(s):  
Electron Microscopy ◽  
Molecular Beam ◽  
Growth Surface ◽  
Ordered Structure ◽  
Phase Boundaries ◽  
Ordered Structures ◽  
Transmission Electron ◽  
Tilting Angle ◽  
High Resolution Images ◽  
Inp Substrates

ABSTRACTCuAu-I type ordered structures in InGaAs grown on (110) InP substrates by molecular beam epitaxy, have been studied by transmission electron microscopy. In the electron diffraction pattern from the InGaAs, superstructure spots associated withCuAu-I type ordered structure are found. When the tilting angle of the substrates increases, the ordering becomes stronger. The ordering is also stronger in crystals grown on substrates tilted toward the <001> or the <001> direction than those on substrates tilted toward the <110> direction. From these results, one can conclude that atomic steps on the growth surface play an important role in the formation of ordered structures. The ordering becomes stronger when the growth temperature increases in the range 360-485°C. In high resolution images of the crystal, doubling in periodicity of 220 and 200lattice fringes is found, which is associated with CuAu-I type ordered structure. Moreover, anti-phase boundaries are very often observed in the ordered regions. It is also found that ordering is not perfect, and that ordered regions are plate-like microdomains lying on planes slightly tilted from the (110) plane.

Effects of illumination spot size on high-resolution image contrast for radiation-sensitive specimens

1986 ◽  
Vol 44 ◽  
pp. 14-17
Author(s):  
Kenneth H. Downing
Keyword(s):  
High Resolution ◽  
Electron Diffraction ◽  
Spot Size ◽  
Image Contrast ◽  
Protein Crystals ◽  
Hexagonal Symmetry ◽  
High Resolution Image ◽  
Lattice Images ◽  
High Resolution Images ◽  
Diffraction Patterns

Electron diffraction patterns of a number of different protein crystals extend to well beyond 0.4 nm. However, until quite recently, no images of these crystals had been obtained which showed such high resolution. The recent introduction of monolayer crystals of paraffin, which diffract at 0.4 nm several thousand times as strongly as typical protein crystals, has made it possible to obtain such high-resolution images almost routinely, and has allowed the study of the causes for the previous lack of success. It has been found that the images of paraffin crystals fall far short of images which could be obtained under ideal circumstances. Not only do the images only rarely show the pseudo-hexagonal symmetry of the crystals, but quantitative analysis of lattice images has shown that under normal conditions the image contrast is typically only about 3-4% of that which is theoretically possible, based on the strength of electron diffraction spots.

Characterization of the (0110) α-Ti/γ-TiH Interface Using High-Resolution Transmission Electron Microscopy (TEM) and Electron Energy Loss Spectroscopy (EELS)

1996 ◽  
Vol 54 ◽  
pp. 108-109
Author(s):  
M. M. Tsai ◽  
J. M. Howe
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Hydrogen Atoms ◽  
Transmission Electron ◽  
High Resolution Tem ◽  
High Resolution Images ◽  
Electron Energy Loss ◽  
Image Simulations

Precipitation of γ-TiH in α-Ti-H alloys involves a hcp → fct lattice transformation with hydrogen as an interstitial diffusing element Results obtained from a previous TEM study have shown that the lengthening rate of γ-TiH is diffusionally controlled at 25°C, and possibly interfacially controlled at temperatures of 50°C and higher. Therefore, it is essential to ascertain the presence or absence of hydrogen atoms at the interface. TEM foils from a 800 ppm wt.% Ti-H alloy were analyzed using high-resolution TEM and image simulations in order to determine the effects of hydrogen on high-resolution images of the α-Ti/γ-TiH interface, and EELS was used to determine the whether the hydnde structure was fully formed up to the interface.

Electronic Cone Illumination with the Conventional Transmission Electron Microscope

1977 ◽  
Vol 35 ◽  
pp. 72-73
Author(s):  
William Krakow
Keyword(s):  
Electronic Device ◽  
Chromatic Aberration ◽  
Objective Lens ◽  
Hollow Cone ◽  
Transmission Electron ◽  
Lissajous Figures ◽  
High Resolution Images ◽  
Imaging Mode ◽  
Diffraction Patterns ◽  
Transmission Microscope

An electronic device has been constructed which manipulates the primary beam in the conventional transmission microscope to illuminate a specimen under a variety of virtual condenser aperture conditions. The device uses the existing tilt coils of the microscope, and modulates the D.C. signals to both x and y tilt directions simultaneously with various waveforms to produce Lissajous figures in the back-focal plane of the objective lens. Electron diffraction patterns can be recorded which reflect the manner in which the direct beam is tilted during exposure of a micrograph. The device has been utilized mainly for the hollow cone imaging mode where the device provides a microscope transfer function without zeros in all spatial directions and has produced high resolution images which are also free from the effect of chromatic aberration. A standard second condenser aperture is employed and the width of the cone annulus is readily controlled by defocusing the second condenser lens.

Transmission Electron Microscopy Studies of Aluminum Oxidation

1985 ◽  
Vol 43 ◽  
pp. 268-269
Author(s):  
J.Y. Lee
Keyword(s):  
Nucleation And Growth ◽  
Ion Milling ◽  
Cross Sectional ◽  
Polycrystalline Aluminum ◽  
Axis Orientation ◽  
Temperature Oxidation ◽  
Aluminum Oxidation ◽  
Transmission Electron ◽  
High Resolution Images ◽  
Argon Ion

In the oxidation of metals and alloys, microstructural features at the atomic level play an important role in the nucleation and growth of the oxide, but little is known about the atomic mechanisms of high temperature oxidation. The present paper describes current progress on crystallographic aspects of aluminum oxidation. The 99.999% pure, polycrystalline aluminum was chemically polished and oxidized in 1 atm air at either 550°C or 600°C for times from 0.5 hr to 4 weeks. Cross-sectional specimens were prepared by forming a sandwich with epoxy, followed by mechanical polishing and then argon ion milling. High resolution images were recorded in a <110>oxide zone-axis orientation with a JE0L JEM 200CX microscope operated at 200 keV.

High-resolution transmission electron microscopic study of highly oxygen doped silicon layer

1989 ◽  
Vol 47 ◽  
pp. 692-693
Author(s):  
H. Takaoka ◽  
M. Tomita ◽  
T. Hayashi
Keyword(s):  
High Resolution ◽  
Oxygen Concentration ◽  
Silicon Layer ◽  
Detailed Structure ◽  
Electron Microscopic ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Doped Silicon ◽  
Argon Ion

High resolution transmission electron microscopy (HRTEM) is the effective technique for characterization of detailed structure of semiconductor materials. Oxygen is one of the important impurities in semiconductors. Detailed structure of highly oxygen doped silicon has not clearly investigated yet. This report describes detailed structure of highly oxygen doped silicon observed by HRTEM. Both samples prepared by Molecular beam epitaxy (MBE) and ion implantation were observed to investigate effects of oxygen concentration and doping methods to the crystal structure.The observed oxygen doped samples were prepared by MBE method in oxygen environment on (111) substrates. Oxygen concentration was about 1021 atoms/cm3. Another sample was silicon of (100) orientation implanted with oxygen ions at an energy of 180 keV. Oxygen concentration of this sample was about 1020 atoms/cm3 Cross-sectional specimens of (011) orientation were prepared by argon ion thinning and were observed by TEM at an accelerating voltage of 400 kV.

Computers and diffraction analysis

1989 ◽  
Vol 47 ◽  
pp. 44-45
Author(s):  
J. A. Eades
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Electron Diffraction ◽  
Diffraction Analysis ◽  
Electron Diffraction Analysis ◽  
Image Simulation ◽  
Correct Interpretation ◽  
High Profile ◽  
High Resolution Images ◽  
Image Simulations

For well over two decades computers have played an important role in electron microscopy; they now pervade the whole field - as indeed they do in so many other aspects of our lives. The initial use of computers was mainly for large (as it seemed then) off-line calculations for image simulations; for example, of dislocation images.Image simulation has continued to be one of the most notable uses of computers particularly since it is essential to the correct interpretation of high resolution images. In microanalysis, too, the computer has had a rather high profile. In this case because it has been a necessary part of the equipment delivered by manufacturers. By contrast the use of computers for electron diffraction analysis has been slow to prominence. This is not to say that there has been no activity, quite the contrary; however it has not had such a great impact on the field.

A Structural Model for a Quasi-Crystalline Material Derived from TEM

1990 ◽  
Vol 48 (1) ◽  
pp. 48-49
Author(s):  
Jan-Olov Bovin ◽  
Osamu Terasaki ◽  
Jan-Olle Malm ◽  
Sven Lidin ◽  
Sten Andersson
Keyword(s):  
High Resolution ◽  
Electron Diffraction ◽  
Structural Model ◽  
Image Intensifier ◽  
Crystalline Materials ◽  
Icosahedral Phases ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Diffraction Patterns ◽  
Quasi Crystals

High resolution transmission electron microscopy (HRTEM) is playing an important role in identifying the new icosahedral phases. The selected area diffraction patterns of quasi crystals, recorded with an aperture of the radius of many thousands of Ångströms, consist of dense arrays of well defined sharp spots with five fold dilatation symmetry which makes the interpretation of the diffraction process and the resulting images different from those invoked for usual crystals. The atomic structure of the quasi crystals is not established even if several models are proposed. The correct structure model must of course explain the electron diffraction patterns with 5-, 3- and 2-fold symmetry for the phases but it is also important that the HRTEM images of the alloys match the computer simulated images from the model. We have studied quasi crystals of the alloy Al65Cu20Fe15. The electron microscopes used to obtain high resolution electro micrographs and electron diffraction patterns (EDP) were a (S)TEM JEM-2000FX equipped with EDS and PEELS showing a structural resolution of 2.7 Å and a IVEM JEM-4000EX with a UHP40 high resolution pole piece operated at 400 kV and with a structural resolution of 1.6 Å. This microscope is used with a Gatan 622 TV system with an image intensifier, coupled to a YAG screen. It was found that the crystals of the quasi crystalline materials here investigated were more sensitive to beam damage using 400 kV as electron accelerating voltage than when using 200 kV. Low dose techniques were therefore applied to avoid damage of the structure.

Automatic Registering and Stitching of TEM/STEM Image Mosaics

2013 ◽  
Author(s):  
Chung-Ching Lin ◽  
Franco Stellari ◽  
Lynne Gignac ◽  
Peilin Song ◽  
John Bruley
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Vlsi Circuit ◽  
Significant Progress ◽  
Research Areas ◽  
Automated Method ◽  
Transmission Electron ◽  
Stem Image ◽  
High Resolution Images ◽  
Global Optimal

Abstract Transmission Electron Microscopy (TEM) and scanning TEM (STEM) is widely used to acquire ultra high resolution images in different research areas. For some applications, a single TEM/STEM image does not provide enough information for analysis. One example in VLSI circuit failure analysis is the tracking of long interconnection. The capability of creating a large map of high resolution images may enable significant progress in some tasks. However, stitching TEM/STEM images in semiconductor applications is difficult and existing tools are unable to provide usable stitching results for analysis. In this paper, a novel fully automated method for stitching TEM/STEM image mosaics is proposed. The proposed method allows one to reach a global optimal configuration of each image tile so that both missing and false-positive correspondences can be tolerated. The experiment results presented in this paper show that the proposed method is robust and performs well in very challenging situations.

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