Development of a high-brightness field-emission lighting device with ITO electrode

There is great interest in improving the brightness of electron sources and therefore the ability of electron optical instrumentation to probe the properties of materials. Extensive work by Dr. Crew and others has provided extremely high brightness sources for certain kinds of analytical problems but which pose serious difficulties in other problems. These sources cannot survive in conventional system vacuums. If one wishes to gather information from the other signal channels activated by electron beam bombardment it is necessary to provide sufficient current to allow an acceptable signal-to-noise ratio. It is possible through careful design to provide a high brightness field emission source which has the capability of providing high currents as well as high current densities to a specimen. In this paper we describe an electrode to provide long-lived stable current in field emission sources.The source geometry was based upon the results of extensive computer modeling. The design attempted to maximize the total current available at a specimen.

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High brightness field emission from carbon nanosheets and back-gated devices

Proceedings 2007 IEEE SoutheastCon ◽

10.1109/secon.2007.342854 ◽

2007 ◽

Author(s):

Mingyao Zhu ◽

Xin Zhao ◽

R. Outlaw ◽

Kun Hou ◽

Peter Miraldo ◽

...

Keyword(s):

Field Emission ◽

High Brightness ◽

Carbon Nanosheets ◽

Brightness Field

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High brightness field emission from printed carbon nanotubes in an S-band microwave gun

Journal of Applied Physics ◽

10.1063/1.4942441 ◽

2016 ◽

Vol 119 (8) ◽

pp. 084504 ◽

Cited By ~ 2

Author(s):

Qilong Wang ◽

Xiangkun Li ◽

Yusong Di ◽

Cairu Yu ◽

Xiaobing Zhang ◽

...

Keyword(s):

Carbon Nanotubes ◽

Field Emission ◽

High Brightness ◽

Brightness Field

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Advantages of a Field Emission Gun for a Combined Analytical and High Resolution Transmission Electron Microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s1431927600000313 ◽

1980 ◽

Vol 38 ◽

pp. 72-73

Author(s):

J. Bentley

Keyword(s):

High Resolution ◽

Field Emission ◽

Operating Conditions ◽

Objective Lens ◽

High Brightness ◽

Transmission Electron ◽

Tem Mode ◽

Brightness Field ◽

High Resolution Microscopy ◽

Current Exposure

This paper describes the various areas of analytical and high resolution microscopy which can be greatly improved by the use of a high-brightness field emission gun (FEG). The instrument used was a Philips EM400T equipped with a FEG, 6585 STEM unit, EDAX EDS detector and Kevex 5100 spectrometer. The <111> oriented W tip was supplied by the manufacturer. The brightness β (current density per unit solid angle) normalized to the ac-celeratiang voltage, V0 is defined by β = 4I/πd2α2jV0, where I is the current in a probe of diameter d and divergence αi. Results are presented in Table 1 for three typical operating conditions. Probe currents >10−7 A have been obtained in the TEM mode which is sufficient for work at medium magnifications (20 to 100 K). Probe currents were measured from the screen current/exposure time system which had been calibrated with a purpose built Faraday cup. Probe diameters in TEM were measured from high magnification TEM images and in STEM by imaging the STEM raster in the TEM mode. This is possible because of the symmetric objective lens which can operate at the same excitation in TEM and STEM. An example is shown in Fig. 1. The values in Table 1 should be compared to conventional W hairpin sources for which β ≅ 1.

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A high brightness field emission display

IEEE Conference Record - Abstracts. 1996 IEEE International Conference on Plasma Science ◽

10.1109/plasma.1996.551466 ◽

2002 ◽

Author(s):

A. Palevsky

Keyword(s):

Field Emission ◽

Field Emission Display ◽

High Brightness ◽

Brightness Field

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Selective Crystalline Seed Layer Assisted Growth of Vertically Aligned MgZnO Nanowires and Their High-Brightness Field-Emission Behavior

Crystal Growth & Design ◽

10.1021/cg900018p ◽

2009 ◽

Vol 9 (10) ◽

pp. 4308-4314 ◽

Cited By ~ 8

Author(s):

Dong Chan Kim ◽

Bo Hyun Kong ◽

Sanjay Kumar Mohanta ◽

Hyung Koun Cho ◽

Jae Hong Park ◽

...

Keyword(s):

Field Emission ◽

Seed Layer ◽

High Brightness ◽

Brightness Field ◽

Emission Behavior ◽

Vertically Aligned

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Characteristics and Application of Temperature-Field Emitters

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100114347 ◽

1975 ◽

Vol 33 ◽

pp. 144-145

Author(s):

N. Tamura ◽

T. Goto ◽

Y. Harada

Keyword(s):

Temperature Field ◽

Electron Microscope ◽

Field Emission ◽

Resolving Power ◽

High Brightness ◽

Field Emitters ◽

Emission Electron ◽

Sufficient Stability ◽

Scanning Electron ◽

Illuminating System

On account of its high brightness, the field emission electron source has the advantage that it provides the conventional electron microscope with highly coherent illuminating system and that it directly improves the, resolving power of the scanning electron microscope. The present authors have reported some results obtained with a 100 kV field emission electron microscope.It has been proven, furthermore, that the tungsten emitter as a temperature field emission source can be utilized with a sufficient stability under a modest vacuum of 10-8 ~ 10-9 Torr. The present paper is concerned with an extension of our study on the characteristics of the temperature field emitters.

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A comparative study on the cold type and thermal type field emission guns used in the same electron microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100107435 ◽

1978 ◽

Vol 36 (1) ◽

pp. 58-59

Author(s):

M. Iwatsuki ◽

Y. Kokubo ◽

Y. Harada

Keyword(s):

Electron Microscope ◽

Field Emission ◽

Signal To Noise Ratio ◽

Electron Source ◽

Resolving Power ◽

Optical Source ◽

Experimental Conditions ◽

High Brightness ◽

Illumination System ◽

Transmission Electron

On accout of its high brightness, small optical source size, and minimal energy spread, the field emission gun (FEG) has the advantage that it provides the conventional transmission electron microscope (TEM) with a highly coherent illumination system and directly improves the resolving power and signal-to-noise ratio of the scanning electron microscope (SEM). The FEG is generally classified into two types; the cold field emission (C-FEG) and thermal field emission gun (T-FEG). The former, in which a field emitter is used at the room temperature, was successfully developed as an electron source for the SEM. The latter, in which the emitter is heated to the temperature range of 1000-1800°K, was also proved to be very suited as an electron source for the TEM, as well as for the SEM. Some characteristics of the two types of the FEG have been studied and reported by many authors. However, the results of the respective types have been obtained separately under different experimental conditions.

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Performance and applications of a field-emission gun TEM/STEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100129346 ◽

1992 ◽

Vol 50 (2) ◽

pp. 942-943

Author(s):

Judith M. Brock ◽

Max T. Otten ◽

Marc. J.C. de Jong

Keyword(s):

Field Emission ◽

High Resolution Imaging ◽

High Quality ◽

Small Energy ◽

High Brightness ◽

Small Probe ◽

Resolution Imaging ◽

Convergent Beam ◽

Beam Patterns ◽

Beam Diffraction

A Field Emission Gun (FEG) on a TEM/STEM instrument provides a major improvement in performance relative to one equipped with a LaB6 emitter. The improvement is particularly notable for small-probe techniques: EDX and EELS microanalysis, convergent beam diffraction and scanning. The high brightness of the FEG (108 to 109 A/cm2srad), compared with that of LaB6 (∼106), makes it possible to achieve high probe currents (∼1 nA) in probes of about 1 nm, whilst the currents for similar probes with LaB6 are about 100 to 500x lower. Accordingly the small, high-intensity FEG probes make it possible, e.g., to analyse precipitates and monolayer amounts of segregation on grain boundaries in metals or ceramics (Fig. 1); obtain high-quality convergent beam patterns from heavily dislocated materials; reliably detect 1 nm immuno-gold labels in biological specimens; and perform EDX mapping at nm-scale resolution even in difficult specimens like biological tissue.The high brightness and small energy spread of the FEG also bring an advantage in high-resolution imaging by significantly improving both spatial and temporal coherence.

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Practical Correction of Three Fold Astigmatism in the Philips CM TEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100164556 ◽

1996 ◽

Vol 54 ◽

pp. 418-419

Author(s):

Arno J. Bleeker ◽

Mark H.F. Overwijk ◽

Max T. Otten

Keyword(s):

Optical Properties ◽

Phase Contrast ◽

The Other ◽

Objective Lens ◽

Symmetric Part ◽

A Posteriori ◽

Contrast Transfer Function ◽

High Brightness ◽

Rotationally Symmetric ◽

Brightness Field

With the improvement of the optical properties of the modern TEM objective lenses the point resolution is pushed beyond 0.2 nm. The objective lens of the CM300 UltraTwin combines a Cs of 0. 65 mm with a Cc of 1.4 mm. At 300 kV this results in a point resolution of 0.17 nm. Together with a high-brightness field-emission gun with an energy spread of 0.8 eV the information limit is pushed down to 0.1 nm. The rotationally symmetric part of the phase contrast transfer function (pctf), whose first zero at Scherzer focus determines the point resolution, is mainly determined by the Cs and defocus. Apart from the rotationally symmetric part there is also the non-rotationally symmetric part of the pctf. Here the main contributors are not only two-fold astigmatism and beam tilt but also three-fold astigmatism. The two-fold astigmatism together with the beam tilt can be corrected in a straight-forward way using the coma-free alignment and the objective stigmator. However, this only works well when the coefficient of three-fold astigmatism is negligible compared to the other aberration coefficients. Unfortunately this is not generally the case with the modern high-resolution objective lenses. Measurements done at a CM300 SuperTwin FEG showed a three fold-astigmatism of 1100 nm which is consistent with measurements done by others. A three-fold astigmatism of 1000 nm already sinificantly influences the image at a spatial frequency corresponding to 0.2 nm which is even above the point resolution of the objective lens. In principle it is possible to correct for the three-fold astigmatism a posteriori when through-focus series are taken or when off-axis holography is employed. This is, however not possible for single images. The only possibility is then to correct for the three-fold astigmatism in the microscope by the addition of a hexapole corrector near the objective lens.

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