• Title, Summary, Keyword: Field Emission

Search Result 2,602, Processing Time 0.049 seconds

Numerical Calculation Study on the Generalized Electron Emission Phenomenon

  • Kim, Hee-Tae;Yu, Soon-Jae
    • Journal of Information Display
    • /
    • v.10 no.4
    • /
    • pp.158-163
    • /
    • 2009
  • There are two kinds of well-known electron emissions from metal: field and thermionic emission. For thermionic emission, electrons come out of a metal due to the thermal energy, whereas for field emission, electrons tunnel out of a metal through the strong electric field. In this study, the most general electron emission caused by the temperature and electric field with a free electron gas model was considered. The total current density of electron emission comes from the field emission effect, where the electron energy is lower than vacuum, and from the thermionic-emission effect, where the electron energy is higher than vacuum. The total current density of electron emission is shown as a function of the temperature for a constant electric field, and as a function of the electric field for a constant temperature.

Electron Emission from $Pb(Zr_xTi_{1-x})O_3$ Ferroelectrics by Pulsed Electric Field (펄스 전기장에 의한 $Pb(Zr_xTi_{1-x})O_3$ 강유전체의 전자 방출)

  • 김용태;윤기현;김태희;박경봉;곽상희
    • Journal of the Korean Ceramic Society
    • /
    • v.37 no.1
    • /
    • pp.6-11
    • /
    • 2000
  • Electron emission from the Pb(ZrxTi1-x)O3 ferroelectrics by pulsed electric field has been investigated as a function of Zr/Ti ratios such as 35/65, 50/50 and 65/35 below 250kV/cm. Electrons were emitted regardless of the applied field polarity to the rear electrode. When the negative field was applied to the rear electrode, the electron emission charge was more stable. It was proved that the electrons were emitted at the edge of the upper electrode. The emission charge increased in order of 65/35>50/50>35/65. The electron emission characteristics were dependent on the ferroelectric properties such as polarization and coercive field. The emission charge and emission threshold field were affected by the polarization change and the coercive field, respectively. This result explains that the electron emission is a field emission with polarization induced surface potential by a modified Fowler-Nordheim plot of emission charge.

  • PDF

Pulse electric field-excited electron emission from Pb$(Zr_xTi_{1-x})O_3$ ceramics prepared by conventional solid state reaction (고상 반응법에 의해 제조된 Pb$(Zr_xTi_{1-x})O_3$ 세라믹스에서 펄스 전계에 의한 전자 방출)

  • Kwak, Sang-Hee;Kim, Tae-Heui;Park, Kyung-Bong;Kim, Chang-Soo
    • Proceedings of the KIEE Conference
    • /
    • /
    • pp.1867-1869
    • /
    • 1999
  • Pulse electric field induced electron emission from ferroelectrics has been studied with Pb$(Zr_xTi_{1-x})O_3$ ceramics with varying Zr/Ti ratio from 35/65 to 65/35, Electron emission was proved to be concentrated on the electrode edge by emission profile test and emission capture photographs. The 65/35 composition showed largest emission charge in lowest field and lowest emission threshold field. The emission characteristics are closely dependent on their ferroelectric properties in hysteresis curve. Electron emission charge increases with the polarization charge and emission threshold voltage is dependent on coercive field regardless of their composition. But dielectric constant has little relation with emission property. Electron emission charge increases exponentially with pulse electric field irrespective of composition. On the assumption that the surface potential is linear with the pulse electric field, electron emission can be regarded as a field emission at the electrode edge using Fowler-Nordheim plot of ln$(Q_e/E_{fe})$ to $1/E_{fe}$.

  • PDF

Investigation of field emission mechanism of undoped polyucrystalline diamond films

  • Shim, Jae-Yeob;Chi, Eung-Joon;Song, Kie-Moon;Baik, Hong-Koo
    • Proceedings of the Korean Vacuum Society Conference
    • /
    • /
    • pp.62-62
    • /
    • 1999
  • Carbon based materials have many attractive properties such as a wide band gap, a low electron affinity, and a high chemical and mechanical stability. Therefore, researches on the carbon-based materials as field emitters have been drawn extensively to enhance the field emission properties. Especially, diamond gives high current density, high current stability high thermal conductivity durable for high temperature operation, and low field emission behaviors, Among these properties understanding the origin of low field emission is a key factor for the application of diamond to a filed emitter and the verification of the emission site and its distribution of diamond is helpful to clarify the origin of low field emission from diamond There have been many investigations on the origin of low field emission behavior of diamond crystal or chemical vapor deposition (CVD) diamond films that is intentionally doped or not. However, the origin of the low field emission behavior and the consequent field emission mechanism is still not converged and those may be different between diamond crystal and CVD diamond films as well as the diamond that is doped or not. In addition, there have been no systematic studies on the dependence of nondiamond carbon on the spatial distribution of emission sites and its uniformity. Thus, clarifying a possible mechanism for the low field emission covering the diamond with various properties might be indeed a difficult work. On the other hand, it is believed that electron emission mechanisms of diamond are closely related to the emission sites and its distributions. In this context, it will be helpful to compare the spatial distribution of emission sites and field emission properties of the diamond films prepared by systematic variations of structural property. In this study, we have focused on an understanding of the field emission variations of structural property. In this study, we have focused on an understanding of the field emission mechanism for the CVD grown undoped polycrystalline diamond films with significantly different structural properties. The structural properties of the films were systematically modified by varying the CH4/H2 ratio and/or applying positive substrate bias examined. It was confirmed from the present study that the field emission characteristics are strongly dependent on the nondiamond carbon contents of the undoped polycrystalline diamond films, and a possible field emission mechanism for the undoped polycrystalline diamond films is suggested.

  • PDF

Properties of Field Emission Electrons for CVD-grown Carbon Nanotubes (CVD법으로 제조한 탄소 나노튜브의 전계 전자 방출 특성)

  • Lee, Rhim-Youl
    • Korean Journal of Materials Research
    • /
    • v.13 no.7
    • /
    • pp.424-428
    • /
    • 2003
  • The microstructure and field emission properties of carbon nanotubes(CNT) grown by Ni-catalytic chemical vapor deposition(CVD) were investigated. CVD-grown CNT had a high density of curved shape with randomly oriented. It was found that an increase in electric field caused an increase in field emission current and field emission sites of CNT. The maximum field emission current density was measured to be 3.6 ㎃/$\textrm{cm}^2$ at 2.5 V/$\mu\textrm{m}$, while the brightness of 56 cd/$\textrm{cm}^2$ was observed for the CNT-grown area of 0.8 $\textrm{cm}^2$ from a phosphor screen. Field emission current at constant electric field gradually decreased initially and then stabilized with time.

Electron Emission Theory for LCD Backlight

  • Kim, Hee-Tae;Lee, Dong-Chin;Nam, Seok-Hyun;Jang, Tae-Seok
    • 한국정보디스플레이학회:학술대회논문집
    • /
    • /
    • pp.1602-1605
    • /
    • 2008
  • We considered most general electron emission caused by temperature as well as electric field with a free electron gas model. The total electron emission current density comes from field emission effect where electron energy is lower than vacuum and from thermionic emission effect where electron energy is higher than vacuum. The total electron emission current density is shown as a function of temperature for constant electric field, and as a function of electric field for constant temperature.

  • PDF

Fabrication of CNT Flexible Field Emitters and Their Field Emission Properties

  • Shin, Dong-Hoon;Song, Yenan;Sun, Yuning;Shin, Ji-Hong;Lee, Cheol-Jin
    • Proceedings of the Korean Vacuum Society Conference
    • /
    • /
    • pp.384-384
    • /
    • 2011
  • Carbon nanotubes (CNTs) have been studied as an ideal material for field emitters due to the high aspect ratio, excellent electrical property and good mechanical strength. There were many reports on CNT emitters fabricated on rigid substrates, but rare reports about CNT flexible field emitters. Recently, we considered that CNTs can be a good candidate for a flexible field emitter material because of their excellent Young's modulus and elasticity, which could not be achieved with metal tips or semiconducting nanowire tips. In this work, we demonstrated the CNT flexible field emitters fabricated by a simple method and studied the field emission properties of the CNT flexible field emitters under various bending conditions. The flexible field emitters showed stable and uniform emission characteristics. Especially, there is no remarkable change of the field emission properties at the CNT flexible field emitters according to the bending conditions. The CNT flexible field emitters also exhibited a good field emission performance like the low turn-on field and high emission current. Therefore, we suggest that the CNT flexible emitters can be used in many practical applications under different bending conditions.

  • PDF

Field emission properties of the silicon field emission arrays coated with diamond-like carbon film prepared by filtered cathodic vacuum arc technique (진공아크방전으로 제작된 다이아몬드상 탄소 박막이 코팅된 실리콘 전계 방출 소자의 전계 방출 특성)

  • 황한욱;김용상
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.13 no.4
    • /
    • pp.326-331
    • /
    • 2000
  • We have fabricated the field emitter arrays coated with diamond-like carbon (DLC) films that improved the field emission characteristics. The nitrogen doped DLC films are prepared by the filtered cathodic vacuum are (FCVA) tehnique. The activation energy of the nitrogen doped DLC films are derived from electrical conductivity measurements. The silicon field emission arrays (FEAs) were prepared by the VLSI technique. The turn-on field was rapidly decreasing and the emission current was remarkably increasing the DLC-coated FEAs than the non-coated silicon FEAs. In the nitrogen doped FEAs, the turn-on field decreased and the emission current increased with increasing the nitrogen found out the field emission current and the work function of the DLC-coated FEAs was remarkably decreased than that of the non-coated silicon FEAs. As nitrogen doping concentrations are increased the work function of FEAs is decreased and the field emission properties are improved in nitrogen doped DLC-coated FEAs. This phenomenon in due the fact that the Fermi energy level moves to the conduction band by increasing nitrogen doping concentration.

  • PDF

Enhanced field emission and luminescent properties of straightened carbon nanotubes for applications in field emission display

  • Kim, Do-Hyung;Jang, Hoon-Sik;Lee, Sung-Youp;Lee, Hyeong-Rag;Kim, Chang-Duk;Cho, Dong-Soo
    • 한국정보디스플레이학회:학술대회논문집
    • /
    • /
    • pp.207-212
    • /
    • 2003
  • The field emission and luminescent properties of carbon nanotubes (CNTs) that were straightened out by argon ion irradiation were investigated. Argon ion irradiation permanently straightened out both as-grown and screen-printed CNTs in the presence of a strong electric field. The straightening process enhanced the emission properties of CNT films by showing a decrease in turn-on field, an increase in total emission current, and a stable emission. Furthermore, the number of emission sites was confirmed to increase by observing the luminescent properties of CNT films after the straightening. The mechanism involved in the straightening of the CNTs is proposed and the enhancement in field emission is discussed in detail.

  • PDF

Thermo-Field emission in silicon nanomembrane ion detector for mass spectrometry (실리콘 나노 박막의 열-전계 방출효과를 이용한 분자 질량분석)

  • Park, Jong-Hoo
    • Journal of the Korean Applied Science and Technology
    • /
    • v.30 no.4
    • /
    • pp.586-591
    • /
    • 2013
  • This paper describes the characteristics of thermo-field emission in a freestanding silicon nanomembrane under ion bombardment with various thermal and field conditions. The thermal effect and field effect in thermo-field emission in silicon nanomembrane are investigated by varying kinetic energy of ions and electric field applied to the silicon nanomembrane surface, respectively. We found that thermo-field emission increases linearly as the electric field increases, when the electric field intensity is lower than the threshold. The thermo-field emission (schottky effect) increases proportionally to the power of temperature, which agree well with the predictions of a thermo-field emission model.