scholarly journals Issues in Cathode Performance Part 3-Cathode Emitter Material

1995 ◽  
Vol 3 (5) ◽  
pp. 10-11
Author(s):  
Damon Heer
Keyword(s):  
Electron Beam ◽  
High Resolution ◽  
Crystal Orientation ◽  
High Stability ◽  
High Brightness ◽  
High Beam ◽  
Industry Standard ◽  
Small Spot ◽  
Long Lifetime ◽  
Beam Currents

Part 1 of this article series (October 1994 issue) covered the performance features of various tip shapes and explained why the <100> crystal orientation is the industry standard. Part 2 (January/February 1995 issue) covered cathode mounting design and explained how the Mini Vogel Mount cathode design provides high-stability and long-lifetime performance.LaB6 and CeB6 cathodes are used as high-brightness, high-stability, longlifetime cathodes in a variety of electron beam applications. A high-brightness source provides small spot sizes for high resolution and improved analytical results from high beam currents.

Small-Spot Illumination For High-Resolution Electron Microscopy of Beam-Sensitive Specimens

1985 ◽  
Vol 43 ◽  
pp. 320-321
Author(s):  
Kenneth H. Downing ◽  
Robert M. Glaeser
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
High Resolution ◽  
Electron Diffraction ◽  
High Resolution Electron Microscopy ◽  
Photographic Emulsion ◽  
Lateral Motion ◽  
Small Spot ◽  
Resolution Electron ◽  
Diffraction Patterns

The contrast observed in images of beam-sensitive, crystalline specimens is found to be significantly less than one would predict based on observations of electron diffraction patterns of the specimens. Factors such as finite coherence, inelastic scattering, and the limited MTF of the photographic emulsion account for some decrease in contrast. It appears, however, that most of the loss in signal is caused by motion of the specimen during exposure to the electron beam. The introduction of point and other defects in the crystal, resulting from radiation damage, causes bending and lateral motion, which degrade the contrast in the image. We have therefore sought to determine whether the beam-induced specimen motion can be reduced by reducing the area of the specimen which is illuminated at any one time.

scholarly journals Issues in Cathode Performance Part 2 - Cathode Mounting Design

1995 ◽  
Vol 3 (1) ◽  
pp. 10-11
Author(s):  
Damon Heer
Keyword(s):  
Electron Beam ◽  
Electron Bombardment ◽  
Thin Wire ◽  
High Brightness ◽  
Temperature Conditions ◽  
Long Lifetime

LaB6 and CeB6 cathodes are widely used as high-brightness, highstability, long-lifetime cathodes in a variety of electron beam appiications. Two of these factors - stability and lifetime - are critically dependent on proper cathode-mounting design.When the benefits of LaB6 as an emitter material were first investigated, the LaB6 was indirectly heated by an electron bombardment coil. This design was cumbersome and did not perform well. Wire mounts, such as those used for tungsten emitters, were developed (and are stili used today); however, they have many drawbacks. Their stability and lifetime are limited because the thin wire mount moves easily and will eventually break under the changing temperature conditions encountered during operation.

X-Ray Microbeam Studies of Electromigration

1999 ◽  
Vol 563 ◽  
Author(s):  
G. S. Cargill III ◽  
A. C. Ho ◽  
K. J. Hwang ◽  
H. K. Kao ◽  
P.-C. Wang ◽  
...  
Keyword(s):  
High Resolution ◽  
Real Time ◽  
High Stability ◽  
Polycrystalline Metal ◽  
Optical Elements ◽  
High Brightness ◽  
X Ray ◽  
Composition Changes ◽  
Stability Energy ◽  
Made In

AbstractThe interplay between stress and electromigration has been recognized since I. A. Blech et al. used x-ray topography in 1976 to demonstrate that stress gradients developed during electromigration. Availability of high brightness synchrotron x-ray sources, high stability energy dispersive detectors, high resolution area detectors, and pinholes, capillaries and other optical elements for forming x-ray microbeams, has made possible more quantitative, real time measurements of strains and composition changes which develop in polycrystalline metal conductor lines during electromigration. This paper describes advances made in this area, implications of results which have been obtained, and prospects for further progress.

The Schottky Source

1991 ◽  
Vol 49 ◽  
pp. 978-979
Author(s):  
L.W. Swanson
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Low Voltage ◽  
High Beam ◽  
Emission Point ◽  
Noise Characteristics ◽  
Beam Currents

The ZrO/W(100) Schottky source is a unique field-assisted, thermionic point cathode which operates at 1800K. It rivals the W(310) cold field emission point cathode in brightness and exceeds it in terms of noise characteristics. It is ideally suited for use in low-voltage microscopy applications where high beam currents and high resolution are needed.

High Resolution Scanning Electron Microscopy

1991 ◽  
Vol 49 ◽  
pp. 478-479
Author(s):  
David Joy ◽  
James Pawley
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Electron Beam ◽  
Electron Microscope ◽  
High Resolution ◽  
Scanning Electron Microscope ◽  
Electron Probe ◽  
Impact Point ◽  
Interaction Volume ◽  
Scanning Electron

The scanning electron microscope (SEM) builds up an image by sampling contiguous sub-volumes near the surface of the specimen. A fine electron beam selectively excites each sub-volume and then the intensity of some resulting signal is measured. The spatial resolution of images made using such a process is limited by at least three factors. Two of these determine the size of the interaction volume: the size of the electron probe and the extent to which detectable signal is excited from locations remote from the beam impact point. A third limitation emerges from the fact that the probing beam is composed of a finite number of discrete particles and therefore that the accuracy with which any detectable signal can be measured is limited by Poisson statistics applied to this number (or to the number of events actually detected if this is smaller).

The method of replication affects metal film granularity and resolution

1989 ◽  
Vol 47 ◽  
pp. 708-709
Author(s):  
George C. Ruben
Keyword(s):  
Electron Beam ◽  
High Resolution ◽  
Film Thickness ◽  
Single Molecule ◽  
Metal Film ◽  
Vertical Surface ◽  
High Resolution Imaging ◽  
Controllable Factors ◽  
Resolution Imaging

Single molecule resolution in electron beam sensitive, uncoated, noncrystalline materials has been impossible except in thin Pt-C replicas ≤ 150Å) which are resistant to the electron beam destruction. Previously the granularity of metal film replicas limited their resolution to ≥ 20Å. This paper demonstrates that Pt-C film granularity and resolution are a function of the method of replication and other controllable factors. Low angle 20° rotary , 45° unidirectional and vertical 9.7±1 Å Pt-C films deposited on mica under the same conditions were compared in Fig. 1. Vertical replication had a 5A granularity (Fig. 1c), the highest resolution (table), and coated the whole surface. 45° replication had a 9Å granulartiy (Fig. 1b), a slightly poorer resolution (table) and did not coat the whole surface. 20° rotary replication was unsuitable for high resolution imaging with 20-25Å granularity (Fig. 1a) and resolution 2-3 times poorer (table). Resolution is defined here as the greatest distance for which the metal coat on two opposing faces just grow together, that is, two times the apparent film thickness on a single vertical surface.

High-resolution observation of sintered alumina (Al2O3) using the specimen-heated and electron-beam-induced conductivity method in a UHR-SEM

1994 ◽  
Vol 52 ◽  
pp. 1046-1047
Author(s):  
K. Ogura ◽  
T. Suzuki ◽  
C. Nielsen
Keyword(s):  
Electron Beam ◽  
High Resolution ◽  
Specimen Preparation ◽  
Conductivity Method ◽  
Fine Grain ◽  
Grain Structures ◽  
Resolution Observation ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Charging Effect

In spite of the complicated specimen preparation, Transmission Electron Microscopes (TEM) have traditionally been used for the investigation of the fine grain structures of sintered ceramics. Scanning Electron Microscopes (SEM) have not been used much for the same purpose as TEM because of poor results caused by the specimen charging effect, and also the lack of sufficient resolution. Here, we are presenting a successful result of high resolution imaging of sintered alumina (pure Al2O3) using the Specimen Heated and Electron Beam Induced Conductivity (SHEBIC) method, which we recently reported, in an ultrahigh resolution SEM (UHR-SEM). The JSM-6000F, equipped with a Field Emission Gun (FEG) and an in-lens specimen position, was used for this application.After sintered Al2O3 was sliced into a piece approximately 0.5 mm in thickness, one side was mechanically polished to get a shiny plane for the observation. When the observation was started at 20 kV, an enormous charging effect occured, and it was impossible to obtain a clear Secondary Electron (SE) image (Fig.1).

Performance and applications of the holography electron microscope

1993 ◽  
Vol 51 ◽  
pp. 1078-1079
Author(s):  
Akira Tonomura
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Phase Measurement ◽  
Electron Holography ◽  
Imaging Method ◽  
High Contrast ◽  
Magnetic Lens ◽  
High Brightness ◽  
Holographic Imaging ◽  
Dynamic Observation

Electron holography is a two-step imaging method. However, the ultimate performance of holographic imaging is mainly determined by the brightness of the electron beam used in the hologram-formation process. In our 350kV holography electron microscope (see Fig. 1), the decrease in the inherently high brightness of field-emitted electrons is minimized by superposing a magnetic lens in the gun, for a resulting value of 2 × 109 A/cm2 sr. This high brightness has lead to the following distinguished features. The minimum spacing (d) of carrier fringes is d = 0.09 Å, thus allowing a reconstructed image with a resolution, at least in principle, as high as 3d=0.3 Å. The precision in phase measurement can be as high as 2π/100, since the position of fringes can be known precisely from a high-contrast hologram formed under highly collimated illumination. Dynamic observation becomes possible because the current density is high.

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