CBED Tools for semi-automatic measurement of crystal thicknesses

2017 ◽  
Vol 50 (1) ◽  
pp. 313-319 ◽  
Author(s):  
Shi Honglong ◽  
Luo Minting ◽  
Wang Wenzhong
Keyword(s):  
Automatic Measurement ◽  
Convergent Beam Electron Diffraction ◽  
Zero Order ◽  
Crystal Thickness ◽  
Beam Electron ◽  
Linear Fitting ◽  
Fitting Method ◽  
Kikuchi Lines ◽  
Convergent Beam ◽  
Thin Crystal

Convergent-beam electron diffraction (CBED) is one of the most popular techniques to measure crystal thickness. The traditional measurement involves linear fitting of several fringes across the CBED disc, but for a thin crystal with fewer than three fringes the usefulness of this method will be limited. CBED Tools, a free plugin for the DigitalMicrograph software, provides a fast (∼1–2 min) and accurate algorithm to measure the crystal thickness on the basis of the linear fitting method, but it is also capable of determining the crystal thickness when it is very thin and only one fringe or part of the first fringe is recorded. CBED Tools can also be utilized to handle the severely distorted CBED pattern obtained when the zero-order Laue zone Kikuchi lines overlap with the fringes.

Strain measurement in In0.2Ga0.8As/GaAs quantum wires by convergent beam electron diffraction

1995 ◽  
Vol 53 ◽  
pp. 444-445
Author(s):  
S. Hillyard ◽  
Y.-P. Chen ◽  
J.D. Reed ◽  
W.J. Schaff ◽  
L.F. Eastman ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Semiconductor Lasers ◽  
Quantum Wire ◽  
Quantum Wires ◽  
Convergent Beam Electron Diffraction ◽  
Zero Order ◽  
Beam Electron ◽  
Local Lattice ◽  
Device Applications ◽  
Convergent Beam

The positions of high-order Laue zone (HOLZ) lines in the zero order disc of convergent beam electron diffraction (CBED) patterns are extremely sensitive to local lattice parameters. With proper care, these can be measured to a level of one part in 104 in nanometer sized areas. Recent upgrades to the Cornell UHV STEM have made energy filtered CBED possible with a slow scan CCD, and this technique has been applied to the measurement of strain in In0.2Ga0.8 As wires.Semiconductor quantum wire structures have attracted much interest for potential device applications. For example, semiconductor lasers with quantum wires should exhibit an improvement in performance over quantum well counterparts. Strained quantum wires are expected to have even better performance. However, not much is known about the true behavior of strain in actual structures, a parameter critical to their performance.

A DigitalMicrograph™ Script for Crystal Thickness Measurements Using Convergent Beam Electron Diffraction

2004 ◽  
Vol 10 (S02) ◽  
pp. 1380-1381 ◽  
Author(s):  
Vincent Hou
Keyword(s):  
Electron Diffraction ◽  
Convergent Beam Electron Diffraction ◽  
Crystal Thickness ◽  
Beam Electron ◽  
Convergent Beam ◽  
Thickness Measurements

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.

scholarly journals Quantitative Convergent Beam Electron Diffraction for Simultaneous Structure Factor and Debye Waller Factor Determination - Fitting Method Optimization

2010 ◽  
Vol 16 (S2) ◽  
pp. 938-939 ◽  
Author(s):  
X Sang ◽  
A Kulovits ◽  
JMK Wiezorek
Keyword(s):  
Electron Diffraction ◽  
Structure Factor ◽  
Waller Factor ◽  
Convergent Beam Electron Diffraction ◽  
Beam Electron ◽  
Debye Waller Factor ◽  
Fitting Method ◽  
Method Optimization ◽  
Convergent Beam

Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010.

Sensitive detection of mirror symmetry by CBED applied to LaAlO3 and GdAlO3

2007 ◽  
Vol 63 (1) ◽  
pp. 69-74 ◽  
Author(s):  
Daniel M. Jones
Keyword(s):  
Electron Diffraction ◽  
Mirror Symmetry ◽  
High Sensitivity ◽  
Convergent Beam Electron Diffraction ◽  
Higher Order ◽  
Zero Order ◽  
Crystal Surfaces ◽  
Beam Electron ◽  
Space Groups ◽  
Convergent Beam

Convergent-beam electron diffraction (CBED) patterns tilted away from major zone axes have been used to re-examine the space groups of LaAlO3 and GdAlO3 perovskites. The higher-order Laue zones (HOLZ) in CBED patterns at such tilted orientations have been found to have high sensitivity to the presence of mirror symmetry. This sensitivity has enabled the space group of LaAlO3, previously claimed to be cubic (Fm\bar 3c), to be confirmed as rhombohedral R\bar 3c by CBED. It is clear that patterns of sufficient tilt will be more sensitive for distinguishing between screw axes and glide planes than the observation of HOLZ deficit lines in zero-order Laue zone reflections. No symmetry degrading effects due to the influence of tilted crystal surfaces could be observed.

Symmetries and Extinction Rules in CBED

1982 ◽  
Vol 40 ◽  
pp. 684-685
Author(s):  
K. Ishizuka
Keyword(s):  
Electron Diffraction ◽  
Incident Beam ◽  
Convergent Beam Electron Diffraction ◽  
Beam Direction ◽  
Beam Electron ◽  
Convergent Beam

The technique of convergent-beam electron diffraction (CBED) has been established. However there is a distinct discrepancy concerning the CBED pattern symmetries associated with translation symmetries parallel to the incident beam direction: Buxton et al. assumed no detectable effects of translation components, while Goodman predicted no associated symmetries. In this report a procedure used by Gjønnes & Moodie1 to obtain dynamical extinction rules will be extended in order to derive the CBED pattern symmetries as well as the dynamical extinction rules.

A library of convergent-beam electron diffraction patterns

1986 ◽  
Vol 44 ◽  
pp. 688-691
Author(s):  
John F. Mansfield
Keyword(s):  
Electron Diffraction ◽  
Materials Science ◽  
Convergent Beam Electron Diffraction ◽  
Beam Electron ◽  
Transmission Electron ◽  
Yield Information ◽  
Analytical Electron ◽  
Diffraction Patterns ◽  
Convergent Beam ◽  
Electron Energy Loss

One of the most important advancements of the transmission electron microscopy (TEM) in recent years has been the development of the analytical electron microscope (AEM). The microanalytical capabilities of AEMs are based on the three major techniques that have been refined in the last decade or so, namely, Convergent Beam Electron Diffraction (CBED), X-ray Energy Dispersive Spectroscopy (XEDS) and Electron Energy Loss Spectroscopy (EELS). Each of these techniques can yield information on the specimen under study that is not obtainable by any other means. However, it is when they are used in concert that they are most powerful. The application of CBED in materials science is not restricted to microanalysis. However, this is the area where it is most frequently employed. It is used specifically to the identification of the lattice-type, point and space group of phases present within a sample. The addition of chemical/elemental information from XEDS or EELS spectra to the diffraction data usually allows unique identification of a phase.

Convergent-beam electron diffraction at high spatial resolution

1992 ◽  
Vol 50 (2) ◽  
pp. 1152-1153 ◽  
Author(s):  
J W Steeds
Keyword(s):  
Electron Diffraction ◽  
High Temperature Superconductors ◽  
Bloch Wave ◽  
Convergent Beam Electron Diffraction ◽  
Beam Electron ◽  
Energy Filtering ◽  
Small Probe ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Convergent Beam

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.

Convergent Beam Electron Diffraction Zone Axis Pattern Map of Zirconium

1990 ◽  
Vol 48 (2) ◽  
pp. 496-497
Author(s):  
E. Silva ◽  
R. Scozia
Keyword(s):  
Electron Diffraction ◽  
Convergent Beam Electron Diffraction ◽  
Zone Axis ◽  
Pole Piece ◽  
Small Particles ◽  
Present Communication ◽  
Beam Electron ◽  
Zero Layer ◽  
Set Up ◽  
Convergent Beam

The purpose in obtaining zone axis pattern map (zap map) from a given material is to provide a quick and reliable tool to identify cristaline phases, and crystallographic directions, even in small particles. Bend contours patterns and Kossel lines patterns maps from Zr single crystal in the [0001] direction have been presented previously. In the present communication convergent beam electron diffraction (CBED) zap map of Zr will be shown. CBED patterns were obtained using a Philips microscope model EM300, which was set up to carry out this technique. Convergent objective upper pole piece for STEM and some electronic modifications in the lens circuits were required, furthermore the microscope was carefully cleaned and it was operated at a vacuum eminently good.CBED patterns in the Zr zap map consist of zero layer disks, showing fine details within them which correspond to intersecting set of higher order Laue zone (HOLZ) deficiency lines.

Large-angle convergent-beam electron-diffraction study of coherent precipitates and decorated dislocations

1996 ◽  
Vol 54 ◽  
pp. 1002-1004
Author(s):  
J.M.K. Wiezorek ◽  
H.L. Fraser
Keyword(s):  
Electron Diffraction ◽  
Angular Resolution ◽  
Large Angle ◽  
Electron Diffraction Study ◽  
Convergent Beam Electron Diffraction ◽  
Crystal Defects ◽  
High Angular Resolution ◽  
Beam Electron ◽  
Diffraction Plane ◽  
Convergent Beam

Conventional methods of convergent beam electron diffraction (CBED) use a fully converged probe focused on the specimen in the object plane resulting in the formation of a CBED pattern in the diffraction plane. Large angle CBED (LACBED) uses a converged but defocused probe resulting in the formation of ‘shadow images’ of the illuminated sample area in the diffraction plane. Hence, low-spatial resolution image information and high-angular resolution diffraction information are superimposed in LACBED patterns which enables the simultaneous observation of crystal defects and their effect on the diffraction pattern. In recent years LACBED has been used successfully for the investigation of a variety of crystal defects, such as stacking faults, interfaces and dislocations. In this paper the contrast from coherent precipitates and decorated dislocations in LACBED patterns has been investigated. Computer simulated LACBED contrast from decorated dislocations and coherent precipitates is compared with experimental observations.

Sign in / Sign up

Export Citation Format

Share Document