• Korean Journal of Materials Research
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• v.11 no.9
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• pp.759-762
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• 2001

Mg$_2$SnO$_4$having an inverse spinel structure was selected as a new host material of $Mn^{2+}$ activator. The luminescence of the $Mg_2$SnO$_4$:Mn phosphor prepared by the solid-state reaction were investigated under ultraviolet and low-voltage electron excitation. The Mn-doped magnesium tin oxide exhibited strong green emission with the spectrum centered at 500nm wavelength. It was explained that the green emission in $Mg_2$SnO$_4$:Mn phosphor is due to energy transfer from $^4T_1to ^6A_1\;of\; Mn^{2+}$ ion at tetrahedral site in the spinel structure. The optimum concentration of $Mn^{2+}$/ion exhibiting maximum emission intensity by the low-voltage electron excitation was 0.6mol%. ？

• Korean Journal of Metals and Materials
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• v.49 no.4
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• pp.342-347
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• 2011

We fabricated the silicon nanodots using the low pressure chemical vapor deposition technique to investigate their electron field emission characteristics. Atomic force microscope measurements performed for the silicon nanodot samples having various process parameters, such as, deposition time and deposition pressure, revealed that the silicon nanodots with an average size of 20 nm, height of 5 nm, and density of $1.3\;{\times}\;10^{11}\;cm^{-2}$ were easily formed. Electron field emission measurements were performed with the silicon nanodot layer as the cathode electrode. The current-voltage curves revealed that the threshold electric field was as low as $8.3\;V/{\mu}m$ and the field enhancement factor reached as large as 698, which is compatible with the silicon cathode tips fabricated by other techniques. These electron field emission results point to the possibility of using a silicon-based light source for display devices.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.3
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• pp.121-124
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• 2002

CNTs(Carbon Nano Tube) were employed as an electron source in electron-gun of CRT(Cathode-Ray Tube). The CNTs were grown on the Si substrates and the electron gun by LP-CVD(Low Pressure-Chemical Vapor Deposition). Their physical and field emission property satisfied the requirements of the electron gun of CRT. The fabricated electron gun was inserted into 19 inch-sifted CRT and its operating properly was evaluated for practical usage.

• Journal of Information Display
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• v.6 no.4
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• pp.35-39
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• 2005

In this paper, we investigate the oxide cathodes for the development of reliable electron sources. Poisoning in oxide cathodes is one of the serious problems in achieving reliable electron emission. In particular, early poisoning induces poor life performance as will be demonstrated herein. The survivability of electron emission sources is significantly improved by high doping of high-speed activator. The robust oxide cathodes with 0.17 % Mg operating at about 1,050 K are expected to work for very long times (>100,000 hours). We suggest that this key idea will contribute to solving the basic problems in oxide cathodes such as poisoning or ion bombardment for high power or high frequency applications of electron sources.

• Journal of Astronomy and Space Sciences
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• v.33 no.2
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• pp.109-117
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• 2016

We explain the results of Yu et al. (2015b) of the novel sharpness angle measurement to a large number of spectra obtained from the Fermi gamma-ray burst monitor. The sharpness angle is compared to the values obtained from various representative emission models: blackbody, single-electron synchrotron, synchrotron emission from a Maxwellian or power-law electron distribution. It is found that more than 91% of the high temporally and spectrally resolved spectra are inconsistent with any kind of optically thin synchrotron emission model alone. It is also found that the limiting case, a single temperature Maxwellian synchrotron function, can only contribute up to 58⁺²³₋₁₈% of the peak flux. These results show that even the sharpest but non-realistic case, the single-electron synchrotron function, cannot explain a large fraction of the observed spectra. Since any combination of physically possible synchrotron spectra added together will always further broaden the spectrum, emission mechanisms other than optically thin synchrotron radiation are likely required in a full explanation of the spectral peaks or breaks of the GRB prompt emission phase.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.55-56
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• 2000

We report the fabrication of carbon nanostureture films with excellent electron-emission characteristics on chrome electrodes using a pre-deposited transition metal catalyst layer. The emission current densities of 1 ${\mu}A/cm^2$ and 1 $mA/cm^2$ were measured at the electric field of 2.5 and 4.8 $V/{\mu}m$, respectively, and the current fluctuation of less than 2.5% was observed at the average current density 211 ${\mu}A/cm^2$ for the measurement duration of 20 minutes. We counted more than ${\sim}10^4$ emission sites per $cm^2$ from the emission images, and also noticed good mechanical stability. Moreover, we were able to fabricate good electron-emitting carbon films on chrome electrodes on Corning glass substrates at the nominal temperature below $650^{\circ}C$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.8
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• pp.634-639
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• 2001

We investigated the etching characteristics of chromium films by using Cl$_2$/O$_2$ gas mixtures with electron cyclotron resonance plasma. In order to examine the chemical etch characteristics of Cr films by using Cl$_2$/O$_2$ gas plasma, we obtained the etch rate with various gas mixing ratios. By X-ray photoelectron spectroscopy, the surface reaction on the chromium films during the etch was examined. From narrow scan analyses of Cr, Cl, and O, it was confirmed that a chromium oxychlorie (CrCl$_{x}$O$_{y}$) layer was formed on the surface by the etch using Cl$_2$/O$_2$ gas mixtures. We observed a new characteristic emission line during the etch of chromium films using Cl$_2$/O$_2$ gas mixtures by an optical emission spectroscopy. It was found that the peak intensity of this emission line had a tendency compatible with the etch rate. The origin of this emission line was discussed in detail. At the same time, the etched profile was also examined by scanning electron microscope.e.e.

• Transactions on Electrical and Electronic Materials
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• v.11 no.2
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• pp.49-53
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• 2010

Microstructural origins of leakage current and physical degradation during operation in product-quality AlGaN/GaN high electron mobility transistor (HEMT) devices were investigated using photon emission microscopy (PEM) and transmission electron microscopy (TEM). AlGaN/GaN HEMTs were fabricated with metal organic chemical vapor deposition on semi-insulating SiC substrates. Photon emission irregularity, which is indicative of gate leakage current, was measured by PEM. Site specific TEM analysis assisted by a focused ion beam revealed the presence of threading dislocations in the channel below the gate at the position showing strong photon emissions. Observation of electrically degraded devices after life tests revealed crack/pit shaped defects next to the drain in the top AlGaN layer. The morphology of the defects was three-dimensionally investigated via electron tomography.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.7
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• pp.634-639
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• 2002

Using laser ablation technique carbon thin films were deposited on Si(100) substrate as a function of substrate temperature. In this study, the surface morphologic, structural and field emission properties of these carbon thin films were investigated using Raman spectroscopy, scanning electron microscopy, and a diode technique, respectively. With increasing of the substrate temperature, the surface morphologies were changed significantly. Moreover, the intensity of D-band and the full width at half maximum of these bands were dependent on substrate temperatures. As the substrate temperature was increased, the field emission properties were improved. As the result, we find that the field emission properties of the films were changed significantly with the substrate temperature and structural features of carbon than films.

• Journal of Korean Vacuum Science & Technology
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• v.3 no.1
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• pp.49-53
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• 1999

We have studied the field emission characteristics of diamond-like-carbon (DLC) films deposited by a layer-by-layer technique using plasma enhanced chemical vapor deposition, in which the deposition of a thin layer of DLC and a CH4 plasma exposure on its surface were carried out alternatively. The hydrogen-free DLC can be deposited by CH4 plasma exposure for 140 sec on a 5 nm DLC layer. N2 gas-phase doping in the CH4 plasma was also carried out to reduce the work function of the DLC. The optimum [N2]/[CH4] flow rate ratio was found to be 9% for the efficient electron emission, at which the onset-field was 7.2 V/$\mu\textrm{m}$. It was found that the hydrogen-free DLC has a stable electron emitting property.