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

2016 ◽  
Vol 119 (8) ◽  
pp. 084504 ◽  
Author(s):  
Qilong Wang ◽  
Xiangkun Li ◽  
Yusong Di ◽  
Cairu Yu ◽  
Xiaobing Zhang ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Field Emission ◽  
High Brightness ◽  
Brightness Field

A Stable Field Emission Electron Source

1977 ◽  
Vol 35 ◽  
pp. 58-59
Author(s):  
W.R. Bottoms ◽  
G.B. Haydon
Keyword(s):  
Field Emission ◽  
Signal To Noise Ratio ◽  
High Brightness ◽  
Electron Sources ◽  
Brightness Field ◽  
Current Densities ◽  
Properties Of Materials ◽  
Stable Field ◽  
Stable Current ◽  
Careful Design

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.

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

2007 ◽  
Author(s):  
Mingyao Zhu ◽  
Xin Zhao ◽  
R. Outlaw ◽  
Kun Hou ◽  
Peter Miraldo ◽  
...  
Keyword(s):  
Field Emission ◽  
High Brightness ◽  
Carbon Nanosheets ◽  
Brightness Field

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

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.

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

Vacuum ◽  
2020 ◽  
Vol 181 ◽  
pp. 109733
Author(s):  
Meng-Jey Youh ◽  
Cheng-Liang Huang ◽  
Yun-Lin Wang ◽  
Li-Ming Chiang ◽  
Yuan-Yao Li
Keyword(s):  
Field Emission ◽  
High Brightness ◽  
Ito Electrode ◽  
Lighting Device ◽  
Brightness Field

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

2009 ◽  
Vol 9 (10) ◽  
pp. 4308-4314 ◽  
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

Characteristics and Application of Temperature-Field Emitters

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.

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

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.

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

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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