Imaging simulation of charged nanowires in TEM with large defocus distance

Microscopy ◽  
2021 ◽  
Author(s):  
Te Shi ◽  
Shikai Liu ◽  
H Tian ◽  
Z J Ding
Keyword(s):  
Electron Beam ◽  
Charge Distribution ◽  
Complete Solution ◽  
Bayesian Optimization ◽  
Electron Optics ◽  
Verification Method ◽  
Transmission Electron ◽  
Imaging Simulation ◽  
Phase Map ◽  
Good Agreement

Abstract In transmission electron microscope (TEM), both the amplitude and the phase of electron beam change when electrons traverse a specimen. The amplitude is easily obtained by the square root of the intensity of a TEM image, while the phase affects defocused images. In order to obtain the phase map and verify the theoretical model of the interaction between electron beam and specimen, a lot of simulations have to be performed by researchers. In this work, we have simulated defocus images of a SiC nanowire in TEM with the method of electron optics. Mean inner potential and charge distribution on the nanowire have been considered in the simulation. Besides, due to electron scattering, coherence loss of the electron beam has been introduced. A dynamic process with Bayesian optimization was used in the simulation. With the infocus image as input and by adjusting fitting parameters, the defocus image is determined with a reasonable charge distribution. The calculated defocus images are in a good agreement with the experimental ones. Here, we present a complete solution and verification method for solving nanoscale charge distribution in TEM.

scholarly journals A novel copper precursor for electron beam induced deposition

2018 ◽  
Vol 9 ◽  
pp. 1220-1227 ◽  
Author(s):  
Caspar Haverkamp ◽  
George Sarau ◽  
Mikhail N Polyakov ◽  
Ivo Utke ◽  
Marcos V Puydinger dos Santos ◽  
...  
Keyword(s):  
Electron Beam ◽  
Optical Transmission ◽  
Pure Copper ◽  
Dielectric Behavior ◽  
Copper Oxidation ◽  
Transmission Electron ◽  
Sum Formula ◽  
Electron Beam Induced Deposition ◽  
High Degree ◽  
Good Agreement

A fluorine free copper precursor, Cu(tbaoac)2 with the chemical sum formula CuC16O6H26 is introduced for focused electron beam induced deposition (FEBID). FEBID with 15 keV and 7 nA results in deposits with an atomic composition of Cu:O:C of approximately 1:1:2. Transmission electron microscopy proved that pure copper nanocrystals with sizes of up to around 15 nm were dispersed inside the carbonaceous matrix. Raman investigations revealed a high degree of amorphization of the carbonaceous matrix and showed hints for partial copper oxidation taking place selectively on the surfaces of the deposits. Optical transmission/reflection measurements of deposited pads showed a dielectric behavior of the material in the optical spectral range. The general behavior of the permittivity could be described by applying the Maxwell–Garnett mixing model to amorphous carbon and copper. The dielectric function measured from deposited pads was used to simulate the optical response of tip arrays fabricated out of the same precursor and showed good agreement with measurements. This paves the way for future plasmonic applications with copper-FEBID.

Techniques for Transmission Electron Microscopy of Fiber-Matrix Interfaces in Aluminum Alloy-Boron Composites by Ion Erosio

1971 ◽  
Vol 29 ◽  
pp. 204-205
Author(s):  
G. G. Shaw
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Aluminum Alloy ◽  
Electron Beam ◽  
Pure Aluminum ◽  
Ion Milling ◽  
Transmission Electron ◽  
Fiber Matrix ◽  
Ion Erosion ◽  
Row Of Fibers

The morphology and composition of the fiber-matrix interface can best be studied by transmission electron microscopy and electron diffraction. For some composites satisfactory samples can be prepared by electropolishing. For others such as aluminum alloy-boron composites ion erosion is necessary.When one wishes to examine a specimen with the electron beam perpendicular to the fiber, preparation is as follows: A 1/8 in. disk is cut from the sample with a cylindrical tool by spark machining. Thin slices, 5 mils thick, containing one row of fibers, are then, spark-machined from the disk. After spark machining, the slice is carefully polished with diamond paste until the row of fibers is exposed on each side, as shown in Figure 1.In the case where examination is desired with the electron beam parallel to the fiber, preparation is as follows: Experimental composites are usually 50 mils or less in thickness so an auxiliary holder is necessary during ion milling and for easy transfer to the electron microscope. This holder is pure aluminum sheet, 3 mils thick.

Domain Formation in Synthetic Quartz

1971 ◽  
Vol 29 ◽  
pp. 156-157
Author(s):  
Joseph J. Comer
Keyword(s):  
Electron Beam ◽  
Room Temperature ◽  
Domain Formation ◽  
Synthetic Quartz ◽  
Transmission Electron ◽  
Black Spots ◽  
Diffraction Mode ◽  
Domain Boundaries ◽  
Kikuchi Lines ◽  
Straight Lines

Domains visible by transmission electron microscopy, believed to be Dauphiné inversion twins, were found in some specimens of synthetic quartz heated to 680°C and cooled to room temperature. With the electron beam close to parallel to the [0001] direction the domain boundaries appeared as straight lines normal to <100> and <410> or <510> directions. In the selected area diffraction mode, a shift of the Kikuchi lines was observed when the electron beam was made to traverse the specimen across a boundary. This shift indicates a change in orientation which accounts for the visibility of the domain by diffraction contrast when the specimen is tilted. Upon exposure to a 100 KV electron beam with a flux of 5x 1018 electrons/cm2sec the boundaries are rapidly decorated by radiation damage centers appearing as black spots. Similar crystallographio boundaries were sometimes found in unannealed (0001) quartz damaged by electrons.

Aspects of microanalysis in a transmission electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 510-511
Author(s):  
R. Sinclair ◽  
B.E. Jacobson
Keyword(s):  
Grain Size ◽  
Electron Beam ◽  
Electron Microscope ◽  
Chemical Analysis ◽  
Transmission Electron Microscope ◽  
Vapor Deposition ◽  
Critical Currents ◽  
X Ray ◽  
Fine Grain ◽  
Transmission Electron

INTRODUCTIONThe prospect of performing chemical analysis of thin specimens at any desired level of resolution is particularly appealing to the materials scientist. Commercial TEM-based systems are now available which virtually provide this capability. The purpose of this contribution is to illustrate its application to problems which would have been intractable until recently, pointing out some current limitations.X-RAY ANALYSISIn an attempt to fabricate superconducting materials with high critical currents and temperature, thin Nb3Sn films have been prepared by electron beam vapor deposition [1]. Fine-grain size material is desirable which may be achieved by codeposition with small amounts of Al2O3 . Figure 1 shows the STEM microstructure, with large (∽ 200 Å dia) voids present at the grain boundaries. Higher quality TEM micrographs (e.g. fig. 2) reveal the presence of small voids within the grains which are absent in pure Nb3Sn prepared under identical conditions. The X-ray spectrum from large (∽ lμ dia) or small (∽100 Ǻ dia) areas within the grains indicates only small amounts of A1 (fig.3).

Reduction of Specimen Contamination in Electron-Beam Instruments

1976 ◽  
Vol 34 ◽  
pp. 576-577
Author(s):  
G. Lehmpfuhl ◽  
P. J. Smith
Keyword(s):  
Electron Beam ◽  
Cold Trap ◽  
Beam Diameter ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Hydrocarbon Molecules ◽  
Electron Microscopes ◽  
Combination Of Methods ◽  
Convergent Beam ◽  
Very High

Specimens being observed with electron-beam instruments are subject to contamination, which is due to polymerization of hydrocarbon molecules by the beam. This effect becomes more important as the size of the beam is reduced. In convergent-beam studies with a beam diameter of 100 Å, contamination was observed to grow on samples at very high rates. Within a few seconds needles began forming under the beam on both the top and the underside of the sample, at growth rates of 400-500 Å/s, severely limiting the time available for observation. Such contamination could cause serious difficulty in examining a sample with the new scanning transmission electron microscopes, in which the beam is focused to a few angstroms.We have been able to reduce the rate of contamination buildup by a combination of methods: placing an anticontamination cold trap in the sample region, preheating the sample before observation, and irradiating the sample with a large beam before observing it with a small beam.

Effects of High-Energy Ions on Synthetic Quartz

1972 ◽  
Vol 30 ◽  
pp. 544-545
Author(s):  
Joseph J. Comer ◽  
Charles Bergeron ◽  
Lester F. Lowe
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
High Energy ◽  
Transmission Electron ◽  
Kikuchi Lines ◽  
High Energy Ions ◽  
Diffraction Patterns ◽  
Dauphiné Twinning ◽  
Beam Damage

Using a Van De Graaff Accelerator thinned specimens were subjected to bombardment by 3 MeV N+ ions to fluences ranging from 4x1013 to 2x1016 ions/cm2. They were then examined by transmission electron microscopy and reflection electron diffraction using a 100 KV electron beam.At the lowest fluence of 4x1013 ions/cm2 diffraction patterns of the specimens contained Kikuchi lines which appeared somewhat broader and more diffuse than those obtained on unirradiated material. No damage could be detected by transmission electron microscopy in unannealed specimens. However, Dauphiné twinning was particularly pronounced after heating to 665°C for one hour and cooling to room temperature. The twins, seen in Fig. 1, were often less than .25 μm in size, smaller than those formed in unirradiated material and present in greater number. The results are in agreement with earlier observations on the effect of electron beam damage on Dauphiné twinning.

Rocking Beam Microarea Diffraction Applied to Metallic thin Films

1976 ◽  
Vol 34 ◽  
pp. 396-397
Author(s):  
R. H. Geiss
Keyword(s):  
Thin Films ◽  
Electron Diffraction ◽  
Small Area ◽  
Objective Lens ◽  
Electron Optics ◽  
Metallic Thin Films ◽  
Transmission Electron Diffraction ◽  
Transmission Electron ◽  
Sample Height ◽  
Scanning Transmission

The theory and practical limitations of micro area scanning transmission electron diffraction (MASTED) will be presented. It has been demonstrated that MASTED patterns of metallic thin films from areas as small as 30 Åin diameter may be obtained with the standard STEM unit available for the Philips 301 TEM. The key to the successful application of MASTED to very small area diffraction is the proper use of the electron optics of the STEM unit. First the objective lens current must be adjusted such that the image of the C2 aperture is quasi-stationary under the action of the rocking beam (obtained with 40-80-160 SEM settings of the P301). Second, the sample must be elevated to coincide with the C2 aperture image and its image also be quasi-stationary. This sample height adjustment must be entirely mechanical after the objective lens current has been fixed in the first step.

Enhanced information from biological materials through technological improvements in cryo-electron microscopy

1992 ◽  
Vol 50 (1) ◽  
pp. 788-789
Author(s):  
Marc J.C. de Jong ◽  
Wim M. Busing ◽  
Max T. Otten
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Biological Materials ◽  
Electron Crystallography ◽  
Cryo Electron Microscopy ◽  
Transmission Electron ◽  
The Many ◽  
Technological Improvements ◽  
Beam Damage

Biological materials damage rapidly in the electron beam, limiting the amount of information that can be obtained in the transmission electron microscope. The discovery that observation at cryo temperatures strongly reduces beam damage (in addition to making it unnecessaiy to use chemical fixatives, dehydration agents and stains, which introduce artefacts) has given an important step forward to preserving the ‘live’ situation and makes it possible to study the relation between function, chemical composition and morphology.Among the many cryo-applications, the most challenging is perhaps the determination of the atomic structure. Henderson and co-workers were able to determine the structure of the purple membrane by electron crystallography, providing an understanding of the membrane's working as a proton pump. As far as understood at present, the main stumbling block in achieving high resolution appears to be a random movement of atoms or molecules in the specimen within a fraction of a second after exposure to the electron beam, which destroys the highest-resolution detail sought.

The use of an energy-filtering electron microscope to reduce chromatic aberration in images of thick biological specimens

1986 ◽  
Vol 44 ◽  
pp. 88-91
Author(s):  
L. D. Peachey ◽  
J. P. Heath ◽  
G. Lamprecht
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
Cross Section ◽  
Electron Scattering ◽  
Chromatic Aberration ◽  
Image Resolution ◽  
Incident Electron Energy ◽  
Energy Filtering ◽  
Transmission Electron

Biological specimens of cells and tissues generally are considerably thicker than ideal for high resolution transmission electron microscopy. Actual image resolution achieved is limited by chromatic aberration in the image forming electron lenses combined with significant energy loss in the electron beam due to inelastic scattering in the specimen. Increased accelerating voltages (HVEM, IVEM) have been used to reduce the adverse effects of chromatic aberration by decreasing the electron scattering cross-section of the elements in the specimen and by increasing the incident electron energy.

Automatic analysis of Kikuchi diffraction patterns

1994 ◽  
Vol 52 ◽  
pp. 900-901
Author(s):  
H. Weiland ◽  
D. P. Field
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Spatial Resolution ◽  
Relevant Information ◽  
Crystalline Materials ◽  
Large Size ◽  
Transmission Electron ◽  
New Type ◽  
Diffraction Patterns ◽  
Orientation Determination

Recent advances in the automatic indexing of backscatter Kikuchi diffraction patterns on the scanning electron microscope (SEM) has resulted in the development of a new type of microscopy. The ability to obtain statistically relevant information on the spatial distribution of crystallite orientations is giving rise to new insight into polycrystalline microstructures and their relation to materials properties. A limitation of the technique in the SEM is that the spatial resolution of the measurement is restricted by the relatively large size of the electron beam in relation to various microstructural features. Typically the spatial resolution in the SEM is limited to about half a micron or greater. Heavily worked structures exhibit microstructural features much finer than this and require resolution on the order of nanometers for accurate characterization. Transmission electron microscope (TEM) techniques offer sufficient resolution to investigate heavily worked crystalline materials.Crystal lattice orientation determination from Kikuchi diffraction patterns in the TEM (Figure 1) requires knowledge of the relative positions of at least three non-parallel Kikuchi line pairs in relation to the crystallite and the electron beam.

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