• Title/Summary/Keyword: emitters

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Analysis of Failure in Miniature X-ray Tubes with Gated Carbon Nanotube Field Emitters

  • Kang, Jun-Tae;Kim, Jae-Woo;Jeong, Jin-Woo;Choi, Sungyoul;Choi, Jeongyong;Ahn, Seungjoon;Song, Yoon-Ho
    • ETRI Journal
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    • v.35 no.6
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    • pp.1164-1167
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    • 2013
  • We correlate the failure in miniature X-ray tubes with the field emission gate leakage current of gated carbon nanotube emitters. The miniature X-ray tube, even with a small gate leakage current, exhibits an induced voltage on the gate electrode by the anode bias voltage, resulting in a very unstable operation and finally a failure. The induced gate voltage is apparently caused by charging at the insulating spacer of the miniature X-ray tube through the gate leakage current of the field emission. The gate leakage current could be a criterion for the successful fabrication of miniature X-ray tubes.

Spatial distrbibution of star formation in extremely strong $H{\alpha}$ emitters

  • Shim, Hyunjin;Chary, Ranga Ram
    • The Bulletin of The Korean Astronomical Society
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    • v.39 no.2
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    • pp.65.1-65.1
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    • 2014
  • We present Palomar/SWIFT integral field spectroscopy of z~0.2 strong $H{\alpha}$ emitters identified in the Sloan Digital Sky Survey. The large Halpha equivalent widths as well as the huge specific star formation rates of these galaxies are comparable with that of z>4 Lyman break galaxies, thus understanding the gas kinematics and the distribution of massive stars in these systems will help to obtain a better understanding of high-redshift star forming environments and the growth of massive galaxies. We measure the velocity dispersion across the entire galaxy, estimate the number density and the spatial distribution of massive stars from the emission line morphologies. The role of minor mergers in powering star formation is investigated as an alternative to cold flow driven star formation.

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Field emission characteristics of carbon nanotubes under residual gases

  • Lee, Han-Sung;Jang, Eun-Soo;Goak, Jeung-Choon;Choi, Young-Chul;Lee, Nae-Sung
    • 한국정보디스플레이학회:학술대회논문집
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    • 2008.10a
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    • pp.1539-1540
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    • 2008
  • The field degradation of carbon nanotube field emitters in diode emission at constant current was demonstrated to be highly dependent upon the presence of residual gases at partial pressures. Upon exposure to a higher pressure of oxygen containing gases, for example, $O_2$ and CO increased the voltage. Those gases give rise to chemical etching to CNTs emitters. On the contrary, $CH_4$ affected the emission properties in the opposite direction as decreasing the voltage which was probably attributed to the introduction of adsorbate tunneling states. The mixed gas may cause a combined effect of both adsorbate tunneling states and CNT etching.

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Ultrahigh Efficiency from Novel Blue Emitters Using a Rational Molecular Design

  • Kim, Soo-Kang;Park, Young-Il;Park, Jong-Wook
    • 한국정보디스플레이학회:학술대회논문집
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    • 2008.10a
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    • pp.921-924
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    • 2008
  • We investigated new deep blue emitting materials including a novel side group such as CB-203. CB-203 shows relatively 40% increased PL quantum efficiency and higher Tg of $30^{\circ}C$ compared to MADN. It exhibits high External Quantum Efficiency (EQE) of 7.18% that is two times bigger than MADN's, which is the best efficiency in case of non-doped blue fluorescence OLED device to our knowledge. And deep blue emitting materials with a new core structure (CB-301) have been synthesized. CB-301 exhibit excellent blue fluorescence properties. Undoped OLED devices using CB-301 as blue emitters was found to deep blue CIE value (0.154, 0.078) and exhibit high luminance efficiencies of 2.01cd/A at $10\;mA/cm^2$.

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Exciton dissociation yields of semiconducting polymer thin film devices doped by various phosphorescent emitters

  • An, J.D.;Chang, J.Y.;Han, J.W.;Im, C.;Chin, B.D.
    • 한국정보디스플레이학회:학술대회논문집
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    • 2006.08a
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    • pp.1010-1013
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    • 2006
  • To understand the exact charge carrier photogeneration properties of photoactive thin films consisting of a ${\pi}-conjugated$ polymer matrix and a triplet dopant, we prepared two types of polymer, poly(9-vinylcarbazole) (PVK) and poly[9,9-bis(2- ethylhexyl)fluorene-2,7-diyl] (PF2/6) doped with triplet emitters for organic light-emitting diodes (OLED), either iridium(III)fac-tris(2-phenylpyridine) $(Ir(ppy)_3)$ or iridium(III)bis[(4,6-fluorophenyl)- $pyridinato-N,C^2'$]picolinate (FIrpic), as thin film devices by using the conventional method. Those doped film devices, as well as pristine film devices, on ITO substrates were characterized by means of steady state photocurrent measurement for a wide spectral range.

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New Current-Voltage Model for Statistically Distributed Field Emitters

  • Lee, Myoung-Bok;Lee, Jae-Hoon;Kwon, Ki-Rock;Hahm, Sung-Ho;Lee, Jong-Hyun;Lee, Jung-Hee
    • 한국정보디스플레이학회:학술대회논문집
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    • 2002.08a
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    • pp.1039-1040
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    • 2002
  • For the I-V modeling of sharp tip arrays and nanostructured planar emitters, we propose a new and much practical I-V relation including tip height and radius by considering a statistical distribution of tip radius. Frequently observed nonlinearity of Fowler-Nordheim plot for sharp tip and tip arrays was successfully simulated and then, an application example was provided to extract relevant emission-governing parameters of sharp tip.

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Fabrication Techniques for Carbon Nanotube Field Emitters by Screen Printing

  • Yi, Mann;Jung, Hyuk;Lee, Dong-Gu;Seo, Woo-Suk;Park, Jong-Won;Chun, Hyun-Tae;Koh, Nam-Je
    • 한국정보디스플레이학회:학술대회논문집
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    • 2002.08a
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    • pp.655-657
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    • 2002
  • The carbon nanotube emitters for field emission displays were fabricated by screen printing techniques. The pastes for screen printing are composed of organic binders, carbon nanotubes, and some additive materials. Then the pastes were printed on Cr-coated/Ag-printed soda-lime glass substrates. From the I-V characteristics, the turn-on field of SWNT was lower than that of MWNT. The decrease in the mesh size of screen masks resulted in decreasing the turn-on field and increasing the electron emission current. When the carbon nanotubes were mixed with glass frit, glass frit appeared to contribute to the vertically aligning of carbon nanotubes on glass.

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Relationship of the Distribution Thickness of Dielectric Layer on the Nano-Tip Apex and Distribution of Emitted Electrons

  • Al-Qudah, Ala'a M.;Mousa, Marwan S.
    • Applied Microscopy
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    • v.46 no.3
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    • pp.155-159
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    • 2016
  • This paper analyses the relationship between the distribution of a dielectric layer on the apex of a metal field electron emitter and the distribution of electron emission. Emitters were prepared by coating a tungsten emitter with a layer of epoxylite resin. A high-resolution scanning electron microscope was used to monitor the emitter profile and measure the coating thickness. Field electron microscope studies of the emission current distribution from these composite emitters (Tungsten-Clark Electromedical Instruments Epoxylite resin [Tungsten/CEI-resin emitter]) have been carried out. Two forms of image have been observed: bright single-spot images, thought to be associated with a smooth substrate and a uniform dielectric layer; and multi-spot images, though to be associated with irregularity in the substrate or the dielectric layer.

Field Emission Display and Backlight for LCD using Printed Carbon Nanotubes

  • Kim, Yong-Churl;Jung, D.S.;Song, B.K.;Bae, M.J.;Kang, H.S.;Han, I.T.;Kim, Jong-Min;Choi, Y.C.;Hwang, M.I.;Kim, I.H.;Park, J.H.
    • 한국정보디스플레이학회:학술대회논문집
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    • 2007.08a
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    • pp.1045-1048
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    • 2007
  • We mainly report recent progress in backlight unit (BLU) for liquid crystal display (LCD) using printed carbon nanotubes (CNTs) including top-gate and lateral gate structures. Lighting performances of CNTBLU and longevity of printed CNT emitters are intensively discussed. Selected issues related with field emission display (FED) using the same emitters also are presented.

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Measurement of Vacuum Pressure by Electron Emission from Carbon Nanotube Emitters (탄소나노튜브 전극으로부터 전자방출에 의한 진공도 측정)

  • Kim, Seong-Jeen;Cho, Kyu-Hwan;Kim, Seong-Yeob;Jeon, Jae-Ok;Lee, Sang-Hoon;Choi, Bok-Gil
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.18 no.5
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    • pp.396-400
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    • 2005
  • Carbon nanotubes (CNTs) have been well known as electron emitters for field emission applications like FEDs. In this work, we propose as new application a vacuum sensor using CNTs and discuss its current-voltage characteristics as a function of vacuum pressure. The proposed sensor, based on electrical discharge theories in air gap well-known as Townsend theory and as Paschen's law, works by figuring out the variation of the dark current and the initial breakdown voltage depending on the vacuum pressure of air which can ionize through collisions with the electrons accelerated by high electric field.