• Vacuum Magazine
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• v.2 no.2
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• pp.24-28
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• 2015

The brightness of an electron source, along with the aberrations of an objective lens, determines the image resolution and beam current on samples, which are two important parameters for evaluating the performance of an electron microscope. Here we introduce thermal electron source, Schottky emitter and cold field electron emitter. Thermal electron source is the cheapest and stable electron source but it has the lowest brightness. Schottky emitter is 10000 times brighter than tungsten thermal electron source, but requires ultrahigh vacuum operating condition. Cold field electron emitter is 10 times brighter than Schottky emitters, but it is rather unstable and its operation requires most stringent vacuum condition, hindering its widespread use.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1998.11a
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• pp.131-133
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• 1998

Electron temperature, electron density and electron energy distribution function were measured in Radio-Frequency Inductively Coupled Plasma(RFICP) using a probe method. Measurements were conducted in argon discharge for pressure from 10 mTorr to 40 mTorr and input rF power from 100W to 600W and flow rate from 3 sccm to 12 sccm. Spatial distribution of electron temperature, electron density and electron energy distribution function were measured for discharge with same aspect ratio (R/L=2). Electron temperature was found to depend on pressure, but only weakly on power. Electron density and electron energy distribution function strongly depended on both pressure and power. Electron density and electron energy distribution function increased with increasing flow rate. Radial distribution of the electron density and electron energy distribution function were peaked in the plasma center. Normal distribution of the electron density, electron energy distribution function were peaked in the center between quartz plate and substrate. These results were compared to a simple model of ICP, finally, we found out the generation mechanism of Radio-Frequency Inductively Coupled Plasma.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.2
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• pp.40-51
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• 1998

Electron transport properties are investigated by Monte Carlo simulation in n-HgCdTe. The material is easily degenerated at low temperature or being slightly doped, and is characterized by small band gap and large nonparabolic factor. The degeneracy is incorporated in the Monte Carlo simulation by taking into account the electron-electron scattering and the pauli exclusion principle. In the conventional method, however, the electron-electron scattering rate was developed under the assumption of parabolic conduction band. A new formulation of the electron-electron scattering rate is develop considering the band nonparabolicity and overlap integral. The electron-electron scattering effects on the electron distribution,impact ionization coefficienty, electron temperature, drift velocity and electron energy are presented.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.4
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• pp.53-60
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• 2008

Electron detectors used in scanning electron microscope accept electrons emitted from the specimen and convert them to an electrical signal that, after amplification, is used to modulate the gray-level intensities on a cathode ray tube, producing an image of the specimen. Electron detector is one of the key components dominating the performance of scanning electron microscope so that the development of electron detectors having high performance is indispensable to acquire high quality images using scanning electron microscope. In this paper, we designed and manufactured an electron detector and conducted a couple of image capture experiments using it. In particular, scintillator which generates light photons when it is struck by high-energy electrons was manufactured and experimental studies on the optimization of manufacturing condition was carried out. From experiments to evaluate the performance of our detector, it was verified that the performance of our detector is equivalent to or better than that of the conventional one.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.5
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• pp.52-57
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• 2008

Most of the electrons emitted from the filament, are captured by the anode. The portion of the electron current that leaves the gun through the hole in the anode is called the beam current. Electron beam probe is called the focused beam on the specimen. Because of the lenes and aperture, the probe current becomes smaller than the beam current. It generate various signals(backscattered electron, secondary electron) in an interaction with the specimen atoms. Backscattered electron provide an useful signal for composition and local specimen surface inclination. Secondary electron is used far the formation of surface imagination. The steady electron beam probe is very important for the imagination formation and the brightness. In this paper, we show the results of developed elements that create electron beam probe and the measured beam probe in various acceleration voltages by Faraday cup. These data are used to analysis and improve the performance of the system in the development.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.208-208
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• 1999

It is found that with increasing power, the measured electron energy distribution by Langmuir probe evolves into a Druyvesteyn-like electron energy distribution in the low-pressure regime of 1mTorr in a small inductively coupled plasma. Electron bounce resonance is introduced to explain the transition of the electron energy distribution against the rf power, The energy diffusion coefficients which determine the shape of the electron energy distribution in elastic range are calculated with and without electron bounce resonance. This electron energy distribution transition is well explained by the electron bounce resonance.

• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.1
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• pp.10-14
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• 2004

A large area electron beam generator has been developed for industrial applications, for example, waste water cleaning, flue gas treatment, and food pasteurization. The operational principle is based on the emission of secondary electrons from the cathode when ions in the plasma contact the cathode, which are accelerated toward the exit window by the gradient of the electric potential. Conventional electron beam generators require an electron beam scanning mechanism because a small area thermal electron emitter is used. The electron beam of the large area electron beam generator does not need to be scanned over target material because the beam area is considerable. We have fabricated a large area electron beam generator with peak energy of 200keV, and a beam diameter of 200mm. The electron beam current has been investigated as a function of accelerating voltage and distance from the extracting window while its radial distribution in front of the extracting window has been also measured.

• Applied Microscopy
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• v.45 no.3
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• pp.150-154
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• 2015

Negative staining electron microscopy facilitates the visualization of small bio-materials such as proteins; thus, many electron microscopists have used this conventional method to visualize the morphologies and structures of biological materials. To achieve sufficient contrast of the materials, a number of imaging parameters must be considered. Here, we examined the effects of one of the fundamental imaging parameters, electron beam exposure time, on electron densities generated using transmission electron microscopy. A single site of a negatively stained biological sample was illuminated with the electron beam for different times (1, 2, or 4 seconds) and sets of micrographs were collected. Computational image processing demonstrated that longer exposure times provide better electron densities at the molecular level. This report describes technical procedures for testing parameters that allow enhanced evaluations of the densities of electron microscopy images.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 1991.05a
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• pp.8-12
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• 1991

Biodegradation of carbon tetrachloride (CTC) in denitrifying and aerobic columns was investigated under various conditions of electron-acceptor and electron-donor availability. CTC removal increased when the electron-acceptor (nitrate) injection was stopped in the denitrifying column ; however, CTC removal decreased when electron donor (acetate) was deleted in the denitrifying and the aerobic column. Small fractions of the CTC removed appeared as chloroform, indicating that reductive dechlorination of CTC was occurring. The results from the denitrifying column support the hypothesis that CTC behave as an electron acceptor that competes for the pool of available electrons inside the bacterial cells.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1996.11a
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• pp.134-139
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• 1996

The electron energy distributions function were analysed in sulphur hexaflouride at E/N : 500~800(Td) for a case of non-equilibrium ion in the mean electron energy. This paper describes the electron transport characteristics in SF$_{6}$ gas calculated for range of E/N values from 150~800(Td) by the Monte Carlo simulation and Boltzmann equation method using a set of electron collision cross sections determined by the authors and the values of electron swarm parameters. The results gained that the value of an electron swarm parameter such as the electron drift velocity, the electron ionization or attachment coefficients, longitudinal and transverse diffusion coefficients agree with the experimental and theoretical for a range of E/N. The properties of electron avalanches in an electron energy non-equilibrium region.n.