Using the TEM Condenser Lens to Switch between Image and Diffraction Modes

2013 ◽  
Vol 21 (2) ◽  
pp. 40-40
Author(s):  
Lydia Rivaud
Keyword(s):  
Electron Microscope ◽  
Diffraction Pattern ◽  
Transmission Electron Microscope ◽  
Condenser Lens ◽  
Selected Area Diffraction Pattern ◽  
Transmission Electron ◽  
Set Up ◽  
Convergent Beam ◽  
Beam Diffraction ◽  
Convergent Beam Diffraction

Central to the operation of the transmission electron microscope (TEM) (when used with crystalline samples) is the ability to go back and forth between an image and a diffraction pattern. Although it is quite simple to go from the image to a convergent-beam diffraction pattern or from an image to a selected-area diffraction pattern (and back), I have found it useful to be able to go between image and diffraction pattern even more quickly. In the method described, once the microscope is set up, it is possible to go from image to diffraction pattern and back by turning just one knob. This makes many operations on the microscope much more convenient. It should be made clear that, in this method, neither the image nor the diffraction pattern is “ideal” (details below), but both are good enough for many necessary procedures.

Convergent-Beam Diffraction in the Characterization of Crystalline Phases

1985 ◽  
Vol 62 ◽  
Author(s):  
J. A. Eades ◽  
M. J. Kaufman ◽  
H. L. Fraser
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Zone Axis ◽  
Crystalline Materials ◽  
Powerful Technique ◽  
Transmission Electron ◽  
Convergent Beam ◽  
Beam Diffraction ◽  
Convergent Beam Diffraction

ABSTRACTConvergent-beam diffraction in the transmission electron microscope is a powerful technique for the characterization of crystalline materials. Examples are presented to show the way in which convergent-beam zone-axis patterns can be used to determine: the unit cell; the symmetry; the strain of a crystal. The patterns are also recognizable and so can be used, like fingerprints, to identify phases.

One of my Failures: Diffraction in the TEM

2011 ◽  
Vol 19 (1) ◽  
pp. 72-72 ◽  
Author(s):  
Alwyn Eades
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Standard Method ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
Convergent Beam ◽  
Beam Diffraction ◽  
Convergent Beam Diffraction

There are two principal techniques for obtaining diffraction patterns in the transmission electron microscope (TEM). They are selected-area diffraction (SAD) and convergent-beam diffraction (CBED). CBED is quicker and easier to use, and it provides a much richer characterization of the sample. Thus, it is clear that CBED should be used in the vast majority of cases. It should be the diffraction technique that students learn first, and students should be taught to consider it the standard method of doing diffraction in the TEM.

Measurement of lattice parameter at the nanometer scale using convergent-beam microdiffraction from a thermal emission source

1993 ◽  
Vol 51 ◽  
pp. 690-691
Author(s):  
W. T. Pike
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Thermal Emission ◽  
Lattice Parameter ◽  
Scanning Transmission Electron Microscope ◽  
Emission Source ◽  
Device Structure ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Convergent Beam

With the advent of crystal growth techniques which enable device structure control at the atomic level has arrived a need to determine the crystal structure at a commensurate scale. In particular, in epitaxial lattice mismatched multilayers, it is of prime importance to know the lattice parameter, and hence strain, in individual layers in order to explain the novel electronic behavior of such structures. In this work higher order Laue zone (holz) lines in the convergent beam microdiffraction patterns from a thermal emission transmission electron microscope (TEM) have been used to measure lattice parameters to an accuracy of a few parts in a thousand from nanometer areas of material.Although the use of CBM to measure strain using a dedicated field emission scanning transmission electron microscope has already been demonstrated, the recording of the diffraction pattern at the required resolution involves specialized instrumentation. In this work, a Topcon 002B TEM with a thermal emission source with condenser-objective (CO) electron optics is used.

Automated Grain Mapping Using Wide Angle Convergent Beam Electron Diffraction in Transmission Electron Microscope for Nanomaterials

2011 ◽  
Vol 17 (6) ◽  
pp. 859-865 ◽  
Author(s):  
Vineet Kumar
Keyword(s):  
Grain Size ◽  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Visual Inspection ◽  
Mapping Method ◽  
Wide Angle ◽  
Inspection Method ◽  
Automated Method ◽  
Transmission Electron ◽  
Convergent Beam

AbstractThe grain size statistics, commonly derived from the grain map of a material sample, are important microstructure characteristics that greatly influence its properties. The grain map for nanomaterials is usually obtained manually by visual inspection of the transmission electron microscope (TEM) micrographs because automated methods do not perform satisfactorily. While the visual inspection method provides reliable results, it is a labor intensive process and is often prone to human errors. In this article, an automated grain mapping method is developed using TEM diffraction patterns. The presented method uses wide angle convergent beam diffraction in the TEM. The automated technique was applied on a platinum thin film sample to obtain the grain map and subsequently derive grain size statistics from it. The grain size statistics obtained with the automated method were found in good agreement with the visual inspection method.

Electron Image Series Reconstruction of Twin Interfaces in InP Superlattice Nanowires

2011 ◽  
Vol 17 (5) ◽  
pp. 752-758 ◽  
Author(s):  
Martin Ek ◽  
Magnus T. Borgström ◽  
Lisa S. Karlsson ◽  
Crispin J.D. Hetherington ◽  
L. Reine Wallenberg
Keyword(s):  
Electron Microscope ◽  
Diffraction Pattern ◽  
Transmission Electron Microscope ◽  
Interface Structure ◽  
Twin Structure ◽  
Twin Interface ◽  
Transmission Electron ◽  
Electron Image ◽  
Model Structures ◽  
Aberration Corrected

AbstractThe twin interface structure in twinning superlattice InP nanowires with zincblende structure has been investigated using electron exit wavefunction restoration from focal series images recorded on an aberration-corrected transmission electron microscope. By comparing the exit wavefunction phase with simulations from model structures, it was possible to determine the twin structure to be the ortho type with preserved In-P bonding order across the interface. The bending of the thin nanowires away from the intended ⟨110⟩ axis could be estimated locally from the calculated diffraction pattern, and this parameter was successfully taken into account in the simulations.

Channel Strain Characterization in Semiconductor Device by Techniques Based on Transmission Electron Microscope

2011 ◽  
Vol 1349 ◽  
Author(s):  
Jinghong Li ◽  
Jeff Johnson ◽  
Dureseti Chidambarrao ◽  
Yunyu Wang ◽  
Anthony G. Domenicucci
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Computer Aided Design ◽  
Semiconductor Device ◽  
Stress Measurement ◽  
Strain Characterization ◽  
Transmission Electron ◽  
Strain Stress ◽  
Convergent Beam ◽  
Aided Design

ABSTRACTThree techniques based on transmission electron microscope (TEM) have been successfully applied to measure strain/stress in the channel area of PMOS semiconductor devices with embedded SiGe in the source/drain areas: convergent beam electron diffraction (CBED), nano beam diffraction (NBD) and dark-filed holography (DFH). Consistent channel strain measurements from the three techniques on the same TEM sample (eSiGe PMOS with 17%Ge) were obtained. Reliable strain/stress measurement results in the channel area have been achieved with very good agreement with computer-aided design (TCAD) calculations.

Image and Diffraction Pattern Rotations in the TEM

2012 ◽  
Vol 20 (5) ◽  
pp. 52-55
Author(s):  
Graham J.C. Carpenter
Keyword(s):  
Electron Microscope ◽  
Diffraction Pattern ◽  
Transmission Electron Microscope ◽  
Image Rotation ◽  
Spiral Path ◽  
Transmission Electron ◽  
Pass Through ◽  
Computer Processor ◽  
Focused Beam ◽  
Imaging Plane

When electrons pass through the electromagnetic lenses in a transmission electron microscope (TEM), they follow a spiral path that results in image rotation. In many TEMs, the image or diffraction pattern that appears at the final imaging plane has therefore suffered a significant rotation compared to the actual specimen. The extent of the rotation is equal to the sum of the contributions from each lens. In some recent instruments an extra lens is built into the column to compensate for these rotations. In the case of a scanning TEM (STEM), where the image is created by scanning a focused beam on the specimen, the orientation of the image to the specimen is fixed but can be controlled electronically by the computer processor.

Seeing is Not Always Believing: Reduction of Artefacts by an Improved Point Resolution With a Spherical Aberration Corrected 200 Kv Transmission Electron Microscope

1997 ◽  
Vol 3 (S2) ◽  
pp. 1179-1180 ◽  
Author(s):  
M. Haider ◽  
S. Uhlemann
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Materials Science ◽  
Imaging System ◽  
Periodic Structures ◽  
Spherical Aberration ◽  
Spatial Frequencies ◽  
Transmission Electron ◽  
Set Up ◽  
Aberration Corrected

The most interesting structures in materials science are non-periodic areas where the crystalline structure is disturbed such as interfaces, defects or dislocations. These non-periodic structures can be hidden by artefacts, caused by aberrations, and therefore they can be easier analysed if an aberration free imaging system can be used. Therefore, in order to improve the point resolution and to obtain easier access to the hidden information, a spherical aberration corrected 200 kV TEM, following a proposal by Rose, was set up.Phase contrast in a transmission electron microscope (TEM) is obtained, as it was shown by Scherzer, due to the phase shifting power of the wave aberrations as there are: the defocus and the spherical aberration. The defocus can be optimised in terms of the well transferred bandwidth of spatial frequencies (Scherzer defocus) Δfsch = (Cs*λ.)1/2. The upper limit of the spatial frequency without a contrast reversal when choosing a Scherzer defocus is called the point resolution d ≈ 0.71 (Cs λ3)1/4.

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