Fabrication and beam characteristics of an ultra-sharp electrode for field emission electron beam

2004 ◽  
Author(s):  
Seong-Soo Kim ◽  
Jong-Hang Lee ◽  
Youn-Chan Yim ◽  
Jung-Woo Hyun ◽  
Cheol-Woo Park ◽  
...  
Keyword(s):  
Electron Beam ◽  
Field Emission ◽  
Emission Electron ◽  
Beam Characteristics

Development of a 1-MV Field-Emission Electron Microscope III. Electron Optical Design and Development of Field-Emission Electron Gun

2000 ◽  
Vol 6 (S2) ◽  
pp. 1142-1143
Author(s):  
Takaho Yoshida ◽  
Takeshi Kawasaki ◽  
Junji Endo ◽  
Tadao Furutsu ◽  
Isao Matsui ◽  
...  
Keyword(s):  
Electron Beam ◽  
Field Emission ◽  
Optical Design ◽  
Electron Gun ◽  
Electron Holography ◽  
Optimized Design ◽  
Emission Electron ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Aharonov Bohm

Bright and coherent electron beams have been opening new frontiers in science and technology. So far, we have developed several field-emission transmission electron microscopes (FE-TEM) with increasing accelerating voltages to provide higher beam brightness. By using a 200-kV FE-TEM and electron holography techniques, we directly confirmed the Aharonov-Bohm effect. A 350-kV FE-TEM equipped with a low-temperature specimen stage enabled us to observe moving vortices in superconductors.2 Most Recently, we have developed a new 1-MV FE-TEM with a newly designed FE gun to obtain an even brighter and more coherent electron beam.Electron beam brightness, Br, defined in Figure 1, is suitable for measuring the performance of electron guns, since both lens aberrations and mechanical/electrical vibrations contribute to a decrease in beam brightness, and beam coherency is proportional to (Br)1/2. Therefore, we optimized design of the illuminating system and its operation by maximizing the electron beam brightness.

Evaluation of a 100 kV thermal field emission electron-beam nanolithography system

2000 ◽  
Vol 18 (6) ◽  
pp. 3089 ◽  
Author(s):  
D. M. Tennant ◽  
R. Fullowan ◽  
H. Takemura ◽  
M. Isobe ◽  
Y. Nakagawa
Keyword(s):  
Electron Beam ◽  
Field Emission ◽  
Thermal Field ◽  
Emission Electron

Holographic contrast transfer theory

1992 ◽  
Vol 50 (2) ◽  
pp. 984-985
Author(s):  
R. Plass ◽  
L. D. Marks
Keyword(s):  
Electron Beam ◽  
Transfer Function ◽  
Field Emission ◽  
Electron Holography ◽  
Contrast Transfer Function ◽  
Beam Focusing ◽  
Emission Electron ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Image Position

With the advent of reliable cold field emission transmission electron microscopes there is substantial interest in using the amplitude and phase information recorded in electron holograms to optically or numerically correct for the coherent aberrations of transmission electron microscopes. However electron holography cannot compensate for incoherent aberrations. The derivation of the contrast transfer function for off axis electron holography in this paper shows there is no fundamental improvement in resolution for electron holography over conventional transmission electron microscopy.Evaluating the contrast transfer function involves mathematically following an electron beam through a field emission electron microscope set up for off axis electron holography. Due to the high coherence of the field emission electron beam coherent aberrations caused by the pre-specimen beam focusing system must be accounted for. Starting with a spacial frequency distribution, C(v), for the electron beam leaving the gun, the electron beam is limited by the condenser aperture and coherently aberrated by the condenser lens and objective pre-field as it passes to the specimen region:

YBCO SQUIDs fabricated by field-emission electron beam source

1999 ◽  
Vol 9 (2) ◽  
pp. 3089-3092
Author(s):  
S.-J. Kim ◽  
J. Chen ◽  
Y. Mizugaki ◽  
K. Nakajima ◽  
T. Yamashita
Keyword(s):  
Electron Beam ◽  
Field Emission ◽  
Beam Source ◽  
Emission Electron

Silicon field emission electron beam sources

1995 ◽  
Author(s):  
D. Palmer ◽  
J. Shaw ◽  
H. Gray ◽  
J. Mancusi ◽  
G.E. McGuire ◽  
...  
Keyword(s):  
Electron Beam ◽  
Field Emission ◽  
Emission Electron

Dynamic Observation of Vortices in Superconductors Using Electron Waves

1995 ◽  
Vol 404 ◽  
Author(s):  
A. Tonomura
Keyword(s):  
Electron Beam ◽  
Field Emission ◽  
Direct Observation ◽  
Point Defects ◽  
Lorentz Microscopy ◽  
Dynamic Observation ◽  
Emission Electron ◽  
Coherent Field ◽  
Lines Of Force

AbstractIndividual vortices in superconductors were directly and even dynamically observed by using a “coherent” field emission electron beam. Magnetic lines of force of vortices were quantitatively observed in a holographic interference micrograph and their dynamics were observed by Lorentz microscopy. The interaction of vortices with both line- and point-defects was investigated by direct observation.

scholarly journals Field-emission electron gun for a MEMS electron microscope

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Michał Krysztof
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Field Emission ◽  
Control Function ◽  
Electron Gun ◽  
Emission Current ◽  
Electron Beam Current ◽  
Anode Current ◽  
Current Limit ◽  
Emission Electron

AbstractThis article presents a field-emission electron gun intended for use in a MEMS (microelectromechanical system) electron microscope. Its fabrication process follows the technology of a miniature device under development built from silicon electrodes and glass spacers. The electron gun contains a silicon cathode with a single very sharp protrusion and a bundle of disordered CNTs deposited on its end (called a sharp silicon/CNT cathode). It was tested in diode and triode configurations. For the diode configuration, a low threshold voltage <1000 V and a high emission current that reached 90 µA were obtained. After 30 min of operation at 900 V, the emission current decreased to 1.6 µA and was stable for at least 40 min, with RMS fluctuation in the anode current lower than 10%. The electron beam spot of the source was observed on the phosphor screen. In the diode configuration, the spot size was the same as the emission area (~10 µm), which is a satisfactory result. In the triode configuration, an extraction electrode (gate) control function was reported. The gate limited the emission current and elongated the lifetime of the gun when the current limit was set. Moreover, the electron beam current fluctuations at the anode could be reduced to ~1% by using a feedback loop circuit that controls the gate voltage, regulating the anode current. The developed sharp silicon/CNT cathodes were used to test the MEMS electron source demonstrator, a key component of the MEMS electron microscope, operating under atmospheric pressure conditions. Cathodoluminescence of the phosphor layer (ZnS:Ag) deposited on the thin silicon nitride membrane (anode) was observed.

The influence of the objective lens current in low magnification electron holography

1995 ◽  
Vol 53 ◽  
pp. 614-615
Author(s):  
B.G. Frost ◽  
D.C. Joy ◽  
E. Völkl ◽  
L.F. Allard
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Field Emission ◽  
Focal Plane ◽  
Reference Wave ◽  
Object Wave ◽  
Objective Lens ◽  
Electron Holography ◽  
Emission Electron

In order to align an electron microscope for low magnification holography we usually completely switch off the objective lens and image the sample by the first intermediate lens. In addition, to achieve a highly coherent electron beam we highly excite the condensor lens resulting in a divergent illumination of the sample and the intermediate lens. Now negatively biasing the fiber of a Möllenstedt type biprism placed between the first an second intermediate lenses of our Hitachi HF-2000 field emission electron microscope creates two virtual sources below the back focal plane of the first intermediate lens. These two sources are necessary to form off-axis holograms. Slightly exciting the objective lens and still imaging the sample by the first intermediate lens results in two major changes in our holograms.First: Due to an electron beam less divergent or even convergent illuminating the first intermediate lens when exciting the objective lens (compare Fig. 1 to Fig.2) the angle β at which object wave and reference wave are superimposed decreases.

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