Carbon Nanotube Field Emission Display Research Articles

Fine tuning of the color of light emitted from Sr1-xCaxS:Mn2+ phosphors for CNT-FEDs

Sr1-xCaxS:Mn2+ phosphors with calcium ion mole fraction (x) values of 0, 0.2, 0.4, 0.6, 0.8, and 1 were synthesized from CaS, SrS, and MnS by carrying out solid-state reactions. Cathodoluminescence (CL) spectra of these phosphors were acquired using moderate voltages in the range 4–10 kV in order to assess their applicability to carbon nanotube field emission displays (CNT-FEDs). The wavelength at the maximum intensity of the CL spectra of the phosphors increases gradually from 549 to 602 nm, and then slightly decreases to 599 nm, as x is increased. This increase can be interpreted in terms of the crystal structures of the phosphors. The ability to tune the color of light emitted from the Sr1-xCaxS:Mn2+ phosphors from greenish yellow to red confirms the promise of these phosphors for use in CNT-FEDs.

Study on the Driving Circuit of Carbon Nanotube Field Emission Display Based on Luminance Control

Carbon nanotube field emission display (CNT-FED) is one of the most significant subjects due to its unique qualities and perfect performance. But there are still some problems in FED, for example, the modulation of each pixel unit of field emission display device is discrete, and the traditional voltage pulse-width modulation driving mode cannot solve luminance non-uniformity and non-linearity of FED. So a novel driving circuit based on cathode current source is proposed. The current driving circuit can be fabricated on Si substrate in advance, and then carbon nanotube is grown at room temperature, carbon nanotube and constant current source circuits are integrated on the same Si substrate. Current source circuit and cathode emission part are integrated together, which not only can solve the FED luminance problem, but also can meet FED thin design.

Secondary electron emission in a triode carbon nanotube field emission display and its influence on the image quality

The secondary electron (SE) emission (SEE) in a triode carbon nanotube (CNT) field emission display (FED) and its influence on the image quality have been studied with a 3.5in. vacuum-sealed FED prototype fabricated by using screen printing and frit sealing techniques. By analyzing the emission property difference of the device under two different kinds of work modes, we have found that it is the SEE from the insulator above the gate that induced the anode image distortion of FED under normal work mode. Two improved structures, by decreasing the size of insulator layer and by coating a conductive layer to stabilize the potential of the insulators, are provided to eliminate SEE influence and achieved a uniform anode image. It is expected that our results will benefit the research and design of CNT FED with high performance.

Using patent analyses to monitor the technological trends in an emerging field of technology: a case of carbon nanotube field emission display

Carbon nanotube field emission display (CNT-FED) represents both emerging application of nanotechnology and revolutionary invention of display. Therefore, it is an important subject to monitor the states and trends of CNT-FED technology before the next stage of development. The present paper uses patent bibliometric analysis and patent network analysis to monitor the technological trends in the field of CNT-FED. These results firstly reveal the different aspects of patenting activities in the field of CNT-FED. Then, patent network analysis indicates the developing tendency of worldwide FED production based on the synthesis of CNT materials. Furthermore, key technologies of three clusters can be identified as the depositing CNT on substrate, coating phosphor on screen and assembling process for whole device. Finally, emitter material is taken for the key factor in R&D work to improve the efficacy in CNT-FED technology.

Microscopic origin of current degradation of fully-sealed carbon-nanotube field emission display

The current-degradation mechanism of a fully sealed, carbon-nanotube field emission display is investigated experimentally and theoretically. From residual gas analysis, it is strongly evidenced that CH 3 radicals from the organic materials in the paste deteriorate emission properties. Based on ab initio methods, it is found that CH 3 radicals can increase electrical resistance of the nanotube and suppress emission currents. In addition, molecular dynamics simulations demonstrate that thermal destruction of CH 3-attached nanotubes occurs at lower temperatures than for pristine nanotubes. Our results suggest that the material selection of the paste is crucial for extending the lifetime of nanotube-based field emission displays.

Enhancement of Dimension Uniformity of Wet-Etched Thick Insulator Holes in Triode Carbon Nanotube Field-Emission Display Devices

A triode structure carbon nanotube field-emission display was fabricated using the thick-film process. The critical dimensional uniformity of wet-etched thick insulator holes was enhanced by changing the wet etching mechanism from vertical dip-etching to horizontal spray-etching. The profile of the insulator holes fabricated using the new etcher was similar to anisotropic. After optimizing the operation conditions of the new etcher, the dimensional uniformity of the insulator holes increased to 97.7%. The optimal concentration of etchant was 2.2 wt % for achieving the least side etching of the insulator holes. The carbon nanotube paste was pattern-printed into the insulator holes. The uniform size of the insulator holes implied that the carbon nanotube distribution was similarly among the insulator holes. This result showed an improved uniform field emission image over the panel from 59 to 83.85%.

Improving the emission characteristics of a carbon nanotube film in NaCl electrolyte

Screen printing is undoubtedly the most cost-effective process for the fabrication of large-sized carbon nanotube field emission display (CNT-FED). A novel post-treatment method in NaCl electrolyte was presented to solve the problem of poor field emission characteristics of printed CNT films. Compared to those of untreated films, the turn-on electric field of the treated film decreased from 2.4 to 1.4V/μm and the total emission current of the treated film that has the same printing area as the untreated one increased from ∼100 to ∼1800μA. Scanning electron microscope (SEM) and Raman spectrum study revealed that field emission characteristics are enhanced by two factors. Firstly, the NaCl electrolyte treatment appeared to render the CNT surfaces more activey by exposing more CNTs from the CNT film. Secondly, the numerous defects of CNTs of the CNT film were increased by electrical current energy.

Improvement of Interpixel Uniformity in Carbon Nanotube Field Emission Display by Luminance Correction Circuit

Interpixel uniformity is critical to image quality, and is hard to be improved by structural reformation of emissive elements because of nonuniformity in luminance characteristics of subpixels in self-emissive device like the carbon nanotube field emission display (CNT-FED). In this paper, we discuss the improvement of the interpixel uniformity by individually controlling the luminance of all subpixels in a display panel. We propose a prototype CNT-FED with improved interpixel uniformity using luminance correction circuitry. The analysis of interpixel uniformity with the proposed luminance correction circuit shows that the index of interpixel uniformity increases about 8% with only about 10% luminance reduction ratio that is a relatively small penalty compared to the enhancement of the interpixel uniformity. The proposed correction method can also be used to ensure improvement of the interpixel uniformity in large-size CNT-FED panels.

Fabrication and properties of Al 2O 3/Cu/InSnO 3 multilayer cathode electrodes in carbon nanotube field emission display

Multilayer cathode electrodes consisting of Al 2O 3 bufferlayer, Cu conductive layer and InSnO 3 current limiting layer, used in carbon nanotube (CNT) field emission display, were prepared by direct current magnetron sputtering and wet etching. Compared with conventional monolayer cathode electrodes, the multilayer electrodes possess higher current limiting resistance with lower inherent resistance variation. Profilometer measurement indicates the etched edges of the multilayer electrodes were abrupt and regular. Nano Indenter experiment shows that the multilayer electrodes remained intact after annealing treatment and were resistance to scratch damage at loads up to 12.6 mN. X-ray diffraction analysis reveals that no oxidized copper was formed during the annealing treatment. Atomic force microscope images show that the surface of the multilayer electrodes became smoother after plasma bombardment, and the maximum protrusion height decreased from 48.6 nm to 15.4 nm. With the multilayer cathode electrodes, the field emission properties of CNT film cathodes, such as uniformity, lifetime and stability are improved.

Cathodoluminescence from a device of carbon nanotube-field emission display with ZnOnanocluster phosphor

Carbon nanotube (CNT) cathodes are electron emitters that operate at room temperature,which are a suitable replacement for thermionic emitters. Cathodoluminescence (CL) ismeasured for the first time with ZnO nanoclusters as a phosphor for a CNT-FED (carbonnanotube-field emission display) device. The CNT cathode is operated in diode mode withbeam currents of 10 and 20 mA and low accelerating voltages of 1.7 and 1.8 kV. CL exhibitstwo peaks: the first peak in the visible range with a broad full width half-maximum(FWHM) and a much narrower second peak (384 nm) in the ultraviolet (UV)range.

37.4: A Study on PWM Driving Schemes for a 20 inch VGA Carbon Nanotube Field Emission Display

AbstractPWM driving schemes for a 20″ carbon nanotube field emission display (CNT‐FED) are studied in this paper. One of their advantages is the inherent ability to linearize the gamma curves of CNT‐FEDs to increase their gray levels and color accuracy. There are, however, some critical problems associated with PWM driving schemes for CNT‐FED. After theoretical analysis of them, several solutions are proposed and experimentally evaluated.

Residual gas analysis based on carbon nanotube field emission display

The authors measured the residual gas spectrum of a field emission display (FED) with carbon nanotube (CNT) emitters and found that the main residual gases inside a sealed CNT FED, containing an evaporated Ba getter, are H2, CH4, CO, Ar, and CO2, all of which are typical residual gases of electronic vacuum tubes. Additionally they also measured the electron stimulated desorption of gases by operating their field emission devices.

Architecture of field emission display based on a gate electrode of diabolo mode

In the normal gate carbon nanotube field emission display (CNT-FED), the gate electrode is used to modulate and address the electron beam. This article proposes a novel gate architecture made on a glass substrate with diabololike funnels. Chemical corrosion was utilized to produce diabolo funnels in the glass dielectric layer. A metal layer was screen printed on the lower surface of the glass-mesh plate as an electron extraction gate electrode. MgO film was vaporized on the wall of the diabolo funnels. The electrons from CNT are transported in a diabolo mode via secondary electron emission over the wall of the diabolo funnel placed above the subemitters. As a result, electrons including the secondary electrons and backscatters are generated and the brightness of the diabolo mode gate architecture CNT-FED could increase obviously.

Measuring hydrogen-carbon gas inside high-vacuum glass panels by the comparative infrared light method

In this article, the authors propose a comparative infrared light method for detecting the hydrogen-carbon (HC) gas inside sealed high-vacuum glass panels. Unlike traditional infrared detection, a comparative infrared light method can distinguish gas species at a relatively short distance, which makes it suitable for carbon-nanotube field-emission display applications. In principle, the comparative infrared light method makes use of a high-vacuum reference panel to determine the existence of the target gas inside a sample panel under test. The authors experimentally demonstrated that residual organic gas (HC related) existed in a 5mm gap between two glass panels at the vacuum level of 10−6torr by this method.

Observation on CNT-FED under various vacuum levels and calculation on number of electron–gas collisions

Based on experimental observation and theoretical analysis, it explicates that light emission of a carbon nanotube-field emission display (CNT-FED) is mainly caused by electron bombardment on the phosphour if the level of vacuum ranges from 10 −4 to 5 Pa. In this case, light emission of the phosphour excited by ultraviolet (UV) light derived from gas discharge cannot be observed. If vacuum level is greater than 5 Pa, no emitted light is observed, since a large amount of gas ionisation reduces the electric potential difference between the cathode and the anode. To analyze collision between electron and gas under field emission conditions, a mathematical and physical model was built. Based on this model the number of electron–gas collisions is calculated. Calculations results indicate that the product of gas pressure and distance between the electrodes ( pd) is a better parameter to characterize the effect of vacuum level for FED than gas pressure only. Calculations results also show that if the distance between the cathode and the anode is increased, it should be to improve the vacuum level to obtain the same effect.

스크린 프린팅 방법에 의해 게이트-에미터간 자체정렬된 3극 구조의 CNT FEA 제조

A carbon nanotube field emission display(CNT FED) panel with a 2 inch diagonal size was fabricated using a screen printing of a prepared photo-sensitive CNT paste and vacuum in-line sealing technology. After a surface treatment of the patterned CNT, only the carbon nanotube tips are uniformly exposed on the surface. The diameter of the exposed CNTs are usually about 20 nm. Using the photo-sensitive CNT paste, we have developed a triode type CNT FEA with a self-aligned gate-emitter structure. The turn on voltage was around 100 V which corresponds to according the turn on field of about <TEX>$40V/{\mu}m$</TEX>. By the creation of a self-aligned gate-emitter structure, it is expected that the screen printed photo-sensitive CNT paste is promising as a good candidate for the large size field emission display.

감광성 CNT 페이스트의 스크린 프린팅법을 이용한 CNT-FEA의 전계 방출 특성

We have fabricated a carbon nanotube field emission display(CNT-FED) panel with a 2 inch diagonal size using a screen printing method and in-situ vacuum sealing technology. The field emission properties of CNT FED panel with square-type CNT emitters. As results, the square-characterized and compared with those of the line-type CNT emitters. As results, the square-type CNT emitters showed much larger emission current and more stable I-V characteristics. Light emission started to be occurred at an electric field of 3.5 V/<TEX>${\mu}m$</TEX> corresponding to the anode-cathode voltage of 700 V. The vacuum level inside of the in-situ vacuum sealed panel was obtained with <TEX>$1.4 {\times} 10^{-5}$</TEX> torr. The sealed panel showed the similar I-V characteristics with the unsealed one and the uniform light emission with very high brightness at a current density of <TEX>$243 {\mu}A/ cm^2$</TEX> obtained by the electric field of 10 V/<TEX>${\mu}m$</TEX>.

63.1: Invited Paper: Recent Improvements in Brightness and Color Gamut of Carbon Nanotube Field Emission Display

The prototype of the field emission display with carbon nanotube emitter is developed in this study. The cathode structure is based on the typical top-gate structure, and electron focusing gate and resistive layer are applied. To improve the brightness and color gamut of the prototype, new phosphor material, SrGa2S4: Eu, is adopted instead of conventional CRT-green phosphor. By replacing the green phosphor, the prototype shows significant improvements in the brightness and color gamut. At the anode voltage of 7 kV and the anode current of 2∼3 μA/cm2, the brightness is higher than 600 cm/m2. The luminous efficiency of the prototype is about 7.7 lm/Watt. The images from color video operation of the prototype are shown.

Field Emission Characteristics Depending on Emitter Patterns of A Screen-Printed Carbon Nanotube Field Emission Array

We have fabricated carbon nanotube field-emission displays (CNT-FEDs) panel with a 2 in. diagonal size using a screen printing method and in-situ vacuum sealing technology. The field emission properties of the CNT-FED panel with square-type CNT emitters were characterized and compared with those of the panel with line-type CNT emitters. As results, the square-type CNT emitters showed a much larger emission current and more stable current–voltage (I–V) characteristics. Light emission started to occur at an electric field of 3.5 V/µm, for a corresponding to an anode–cathode voltage of 700 V. The vacuum level inside of the in-situ vacuum-sealed panel was 1.4×10-5 Torr. The sealed panel showed similar I–V characteristics with the unsealed one and uniform light emission with very high brightness at a current density of 243 µA/cm2 obtained at an electric field of 10 V/µm.

The fabrication and operation of fully printed Carbon nanotube field emission displays

Screen-printing is undoubtedly the most cost effective process for the fabrication of large-sized carbon nanotube field emission display (CNT-FED). A novel post-treatment method of mechnical crushing and blowing was presented to solve the problem of poor field emission properties of printed CNT films. The turn-on electric field of the treated film decreased and the emission current increased distinctly. Then a technique was developed to fabricate fully printed CNT-FED in which all the inner cells were fabricated by screen-printing process. Based on this technique, fully printed matrix-addressable diode CNT-FEDs, which can display moving image and be driven by the integrated drive circuits of commercial plasma display panel (PDP), were fabricated subsequently. A very high brightness of 1×104cd/m2 can be achieved at 220V.