A Field Emission Scanning Electron Microscope Operating in the Secondary Electron Imaging Mode

1972 ◽  
Vol 30 ◽  
pp. 434-435
Author(s):  
T. Komoda ◽  
S. Saito ◽  
Y. Kakinuma ◽  
A. Okura
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Field Emission ◽  
Secondary Electron ◽  
Electron Gun ◽  
Emission Current ◽  
Electron Imaging Mode ◽  
Imaging Mode ◽  
Electron Imaging ◽  
Scanning Electron

The authors have built a surface scanning electron microscope incorporating a field emission electron gun. The gun has a brightness almost three order of magnitude higher than that of the ordinary thermionic electron gun, which is promissing high resolution in the secondary electron imaging mode.Emission current fluctuation, which is one of the most serious problems in field emission guns, depends on the vacuum condition around the field emission tip. In order to provide a good vacuum environment, the gun assembly in this microscope is located in the center of an ion-pump system which is symmetrically laid out relative to the electron optical axis. Two tips are mounted on a turret holder and they are exchangeable from the outside without disturbing the vacuum in the gun chamber. A stable emission current of the order of 10μA is obtainable at the normal vacuum operation better than 5x10-10 Torr.

An Electron Gun Scanning Microscope

1968 ◽  
Vol 26 ◽  
pp. 360-361
Author(s):  
A. V. Crewe ◽  
D. Johnson ◽  
M. Isaacson
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Field Emission ◽  
Beam Current ◽  
Angular Spread ◽  
Electron Gun ◽  
Emission Current ◽  
Scanning Microscope ◽  
Schematic Drawing ◽  
Scanning Electron

A simple scanning electron microscope has been built using a field emission electron gun. The gun is used alone, without the aid of auxiliary lenses, and is theoretically capable of producing a 100 Å probe with a beam current of 10-10 A. Such a beam current allows scan times of the order of a few seconds.A schematic drawing of the microscope is shown in Fig. 2. The field emission voltage is applied to the first anode which controls the emission current. An accelerating voltage is applied to the second anode, and the field between the anodes focuses the electrons to form an image of the tip at the specimen. The angular spread of the beam is limited by an aperture on the second anode.

Novel and Advanced Applications of the Low Vacuum and Environmental Scanning Electron Microscope (SEM)

1997 ◽  
Vol 3 (S2) ◽  
pp. 385-386 ◽  
Author(s):  
Brendan J. Griffin
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Secondary Electron ◽  
Electron Gun ◽  
Environmental Scanning ◽  
Electron Detector ◽  
Environmental Sem ◽  
Practical Sense ◽  
Advanced Applications ◽  
Scanning Electron

The environmental SEM is an extremely adaptive instrument, allowing a range of materials to be examined under a wide variety of conditions. The limitations of the instrument lie mainly with the restrictions imposed by the need to maintain a moderate vacuum around the electron gun. The primary effect of this has been, in a practical sense, the limited low magnification available. Recently this has been overcome by modifications to the final pressure limiting aperture and secondary electron detector (Fig.l). The modifications are simple and users should be brave in this regard.A variety of electron detectors now exist including various secondary, backscattered and cathodoluminescence systems (Figs 2-5). These provide an excellent range of options; the ESEM must be regarded as a conventional SEM in that a range of imaging options should be installed. In some cases, e.g. cathodoluminescence, the lack of coating provides an advantage unique to the low vacuum SEMs.

Imaging thin and thick sections of biological tissue with the secondary electron detector in a field-emission scanning electron microscope

Scanning ◽  
2006 ◽  
Vol 19 (6) ◽  
pp. 387-395 ◽  
Author(s):  
William P. Wergin ◽  
Robert W. Yaklich ◽  
Stéphane Roym ◽  
David C. Joy ◽  
Eric F. Erbe ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Field Emission ◽  
Biological Tissue ◽  
Secondary Electron ◽  
Electron Detector ◽  
Scanning Electron

A Compact Field Emission Scanning Electron Microscope

1971 ◽  
Vol 29 ◽  
pp. 32-33 ◽  
Author(s):  
L. M. Welter ◽  
V. J. Coates
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Field Emission ◽  
Electron Gun ◽  
Readout System ◽  
Amplitude Control ◽  
Emission Electron ◽  
Compact Field ◽  
New Instrument ◽  
Scanning Electron

A compact field emission scanning electron microscope has been developed and modeled after the optical microscope. The new instrument consists of the field emission electron gun, an externally adjustable aperture strip containing four different hole sizes, an electromagnetic single deflection system, an electromagnetic stigmator with independent magnitude and amplitude control, an ion pumped specimen chamber, and a television readout system. No magnetic lenses are used.The field emission electron gun incorporates an electrode system which simultaneously accelerates and focuses the electrons drawn from a field emission source. Several improvements have been made in the basic gun to provide for higher tip stability and reliability. A unique pumping scheme has been incorporated in the gun to provide tip region pressures in the order of 10-9 Torr and below so that stable field emission can be routinely obtained.

Secondary-Electron imaging by Scintillating Gaseous Detection Device

1992 ◽  
Vol 50 (2) ◽  
pp. 1302-1303 ◽  
Author(s):  
G. D. Danilatos
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Secondary Electron ◽  
Environmental Scanning Electron Microscope ◽  
Environmental Scanning ◽  
Specimen Preparation ◽  
Additional Signal ◽  
Gaseous Environment ◽  
Electron Imaging ◽  
Scanning Electron

The environmental scanning electron microscope (ESEM) incorporates the functions of the conventional SEM while it has the added capability of allowing the examination of virtually any specimen in a gaseous environment. The main modes of imaging are all represented in the ESEM, and some developments with regard to the secondary electron (SE) mode are reported herewith.The conventional E-T detector fails to operate in the gaseous conditions of ESEM, but this obstacle has been overcome with the advent of a gaseous detection device (GDD). The principle of operation of this device is based on the monitoring of the products of interaction between signals and gas. Initially, the ionization from the signal/gas interaction was used to produce images of varying contrast and, later, the gaseous scintillation, from the same interaction, was also used to produce images. First, a low bias was applied to various electrodes but later a much higher bias was used for the purpose of achieving additional signal gain. By careful shaping and positioning the respective electrode, it was shown that SE imaging is possible in the ESEM. This has been also independently demonstrated by use of a special specimen preparation.

Development of 100 kV Field Emission Scanning Electron Microscope

1974 ◽  
Vol 32 ◽  
pp. 408-409
Author(s):  
H. Koike ◽  
Y. Harada ◽  
T. Goto ◽  
Y.Kokubo ◽  
K. Yamada ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Field Emission ◽  
Chemical Elements ◽  
Signal To Noise Ratio ◽  
Electron Gun ◽  
The Past ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Scanning Electron

During the past ten years, the resolution of the CTEM has been improved to a theoretical value determined by spherical and diffraction aberrations. In the scanning electron microscope, however, the resolution is restricted by the signal-to-noise ratio. Crewe et al were the first to increase the resolution by applying a field emission source to a 35 kV scanning electron microscope, resulting in a 5 Å resolution. Owing to its prominent brightness, the feild emission electron gun promises to increase not only the resolution of STEM images, but also to realize an analytical electron microscope which identifies chemical elements, crystalline structures and chemical bonding in specimen microareas in the order of less than 100 Å.

Microprocessor control of a field-emission scanning electron microscope (Model S-800)

1983 ◽  
Vol 41 ◽  
pp. 410-411
Author(s):  
S. Saito ◽  
Y. Nakaizumi ◽  
T. Nagatani ◽  
H. Todokoro
Keyword(s):  
Electron Microscope ◽  
Control System ◽  
Scanning Electron Microscope ◽  
Field Emission ◽  
Operating Conditions ◽  
Gun Control ◽  
Electron Gun ◽  
Microprocessor Control ◽  
Emission Electron ◽  
Scanning Electron

We have developed an ultra high resolution scanning electron mícroscope utílízíng a fíeld emíssíon electron source (Fig.1). This instrument has a guaranteed resolution of 2 nm in the secondary electron image mode and it has incorporated a microprocessor control for optimized operating conditions and maximum ease of operation by various automated functions. The microprocessor control system includes field emission electron gun control, electron optical system control, and video signal control. The field emission electron gun control system includes flashing operation which is used to clean the tip surface by heating for a very short time, high voltage operation of accelerating voltage (V0) and tip voltage (V1), correction of emission current which changes with time, and correction of virtual source position which changes with a voltage ratio V0/V1. We have automated these series of operations by developing an auto FE gun control system. Fig. 2 shows details of this system.

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