Field Emission Flat Panel Display Research Articles

Design and fabrication of field‐emission tips with self‐aligned gates

A novel approach to the design and fabrication of field-emission tips with self-aligned gates intended for electric propulsion micro-thruster applications is presented. Their micro-electromechanical systems fabrication process is derived from the recent proliferation of research toward developing field emitter arrays, which are used primarily for field-emission flat-panel display applications. An array of micron-sized tips for electric field enhancement via wet isotropic etching of silicon, using silicon nitride as a hard mask is fabricated. The wet etching is accomplished using a combination of hydrofluoric, nitric, and acetic acids. The tips were then coated with a metal layer to enhance wetting by indium, the proposed propellant. Next, a layer of SU-8 photoresist was applied by spin coating and patterned to serve as a dielectric spacer. A second layer of metal was then applied to serve as a gate electrode. In addition, the results of electrostatic simulations of the prototype is described.

Carbon-Coated Porous Aluminum Oxides Used as Spacer Overlayers to Reduce Secondary Electron Emission for Field Emission Display Applications

Porous surface structures can mitigate the charging effect of vacuum spacers of field-emission flat panel display due to the abundance of secondary electrons (SEs) emitted from the spacers during field emission display (FED) operation. In this study, we fabricated porous anodic aluminum oxide (AAO) overlayers on glass substrates to examine the effect of carbon deposition on the reduction of SE emissions. This paper reports that uniform AAO overlayers can be simultaneously prepared on both sides of a glass plate 2 ×10 cm2 in size. The SE emission of the AAO overlayer was examined by using an Auger electron microscope. When a small amount of carbon is evaporation-deposited on the as-prepared AAO overlayer, the SE emission efficiency is significantly decreased and the reduction in the SE emission is ascribed to the low SE yield of the carbon deposit and the suppression of SE escape from the narrowed pore channels. However, a heavy deposition of carbon results in a smaller surface roughness of the AAO overlayer, thereby increasing SE emission. The carbon-coated AAO overlayer demonstrates favorable electrical and mechanical properties, making it suitable for use in FED vacuum spacers.

Electron transferring from titanium ion irradiated carbon nanotube arrays into vacuum under low applied fields

Field emission characteristics of carbon nanotube arrays synthesized by thermal chemical vapor deposition on iron ion pre-bombarded silicon substrate are enhanced by titanium ion irradiation. A pronounced degradation of turn-on electric field of 0.305 V/μm and threshold field, of which the lowest value is only 1.054 V/μm, about 0.482 V/μm at the dose of 5 × 10 16 ions/cm 2 is as an expression of this enhancement. Scanning electron microscopy, Raman spectroscopy, x-ray photoelectron spectroscopy, Photoelectron spectrometer and transmission electron microscopy are measured for comparison before and after the Ti ion irradiation of the carbon nanotube arrays, and the results reveal that the formation of carbon nanorod/nanotube heterostructure during ion irradiation plays a dominative role in the promotion of the field emission properties. However, high-dose irradiating transaction on carbon nanotube arrays will exert repulsive effects on the field emission characteristics for the introduction of severe structural damage. Additionally, the longtime eminent stability behaviors under high applied fields have provided a possibility for the potential application of field emission flat panel display or electron emitters based on carbon nanotube arrays.

ZnO nanostructures grown on zinc nanocones by thermal oxidation

ZnO nanostructures were grown on metallic zinc nanocones by thermal oxidation. The metallic nanocones are prepared by argon ion beam sputtering utilizing a capillaritron ion source. The aspect ratios of zinc nanocones are found to be dependent on ion beam energy and substrate temperatures. By maintaining the substrate temperature to be less than 60°C, the aspect ratio of zinc nanocones increases from 1.2 to 2.7 as ion beam energy increases from 6to12keV. Zn nanocones with aspect ratio larger than 25 are obtained by utilizing a 12keV ion beam and allowing the substrate to increase to ∼180°C by in situ ion beam heating. Thermal oxidation of zinc nanocones results ZnO nanowires and nanoblades grown outwardly from the shank. This provides a convenient route for the fabrication of ZnO nanowires for field emission flat panel display and dye-sensitized solar cell applications.

La B 6 tip-modified multiwalled carbon nanotube as high quality field emission electron source

An effective field emitter has been developed by modifying an individual multiwalled carbon nanotube (MWCNT) tip with LaB6. The modified emitter possesses the merits of both the MWCNT and LaB6, which presents a significant low turn-on voltage, good emission properties, and long lifetime. As a result, a total current of 70μA has been reached at a very low electric field of only 1.2V∕μm for an individual modified MWCNT emitter, which is also expected to have advantages of high brightness and coherence, clearly indicating great promise for practical applications such as electron guns or cathodes for field emission flat panel display.

Field emission from ZnO nanorods

The field emission properties of the randomly oriented and the well-aligned ZnO nanorods synthesized by a thermal evaporation method were investigated in detail. It was found that the field emission of the well-aligned ZnO nanorods is seriously affected by the screening effect. While, compared with the ZnO arrays, the field emission measurements on the randomly oriented ZnO nanorods show a lower turn-on filed and a larger field enhancement factor, which are attributed to the weak screening effect and the surface perturbations. These features make the random ZnO nanorods as a competitive candidate for field emission flat panel display.

Field emission and photofluorescent characteristics of zinc oxide nanowires synthesized by a metal catalyzed vapor-liquid-solid process

The ZnO nanowires synthesized by vapor-liquid-solid growth mechanism with Cu and Au as the catalyst were investigated. The principal differences in morphology between Cu and Au catalyzed ZnO nanowires are observed and lead to significant differences in their field emission and photofluorescent characteristics. The Cu catalyzed ZnO nanowires with a high-quality wurtzite structure were grown vertically on p-type Si(100) substrate along [0002] direction. A strong ultraviolet emission at 381 nm is observed. These ZnO nanowires show excellent field emission properties with turn-on field of 0.83 V/μm and corresponding current density of 25 μA/cm2. The emitted current density of the ZnO nanowires is 1.52 mA/cm2 at a bias field of 8.5 V/μm. The large field emission area factor, β arising from the morphology of the nanowire field emitter, is partly responsible for the good emission characteristics. The ZnO nanowires with high emission current density and low turn-on field are expected to be used in field emission flat panel display.

Study of a microprocessor-based technique for improving the uniformity of a field-emission flat-panel display

The nonuniformity in field emission is still a critical problem hampering the commercial application of field-emission displays. In the present study, a microprocessor-based technique is developed to overcome this difficulty in order to finally improve the display uniformity. The principle of the technique and the experimental details are given. One of the key functions of this method, i.e., control of emission-current level, was investigated. This capability was then demonstrated by using it to control the performance of a single lighting element, i.e., a pixel of an ultralarge display screen.

Characterization of a high voltage flat panel display unit using nanotube-based emitters

Details are given of an experimental investigation carried out to study the field electron emission characteristics of a field emission flat panel display unit using a carbon nanotube-epoxy composite as electron emission material. These include: (i) dependence of direct emission current–voltage characteristic on vacuum gap spacing, (ii) the variation of the proportion of emission current passing through an aperture hole of a gate electrode with changing structural parameters of the device, and (iii) the uniformity and display characteristics of a typical display unit. Our findings indicate that it is very likely for one to produce a near-market prototype high voltage field emission flat panel display, if more sophisticated fabrication and assembly technique is adapted.

Fabrication of Carbon Nanotube Film Arrays for Field Emission Flat Panel Display Application

The unique electron field emission properties of carbon nanotube films are promising for flat panel display application as the cold cathode. In this work, the multiwall carbon nanotube (10–102 nm in diameter, and 103–104 nm in length) film arrays (the pixel size: 50 μm ×50 μm) were deposited on the patterned Ni–Si substrate from hydrocarbon precursor (C2H2/H2) by chemical vapor deposition at low temperature (550°C). The patterned films were characterized by scanning electron microscopy and Raman spectroscopy. The carbon nanotube film arrays exhibit good electron emission properties, e.g. low threshold emission field (below 2 V/μm), high emission current density (above 1 mA/cm2 at 10 V/μm), and high emission luminance spot density on the phosphor coated-ITO(indium tin oxide)-glass anode. These properties are good enough for high-resolution flat panel display application using carbon nanotube film arrays as the cathode.

Single wall carbon nanotubes and their electrical properties

Single-wall carbon nanotubes (SWCNTs) were synthesized and purified. A water colloid of SWCNTs was prepared and used to assemble SWCNTs onto a gold film surface. Scanning tunneling microscopy (STM) images showed that short SWCNTs stood on gold film surfaces. Using STM tips made of SWCNTs, a crystal grain image of a gold thin film and an atomic resolution image of highly oriented pyrolytic graphite were successfully obtained. The electrical properties of short SWCNTs, which stood on the surface of gold film, were measured using STM. That SWCNTs stand on gold thin films is a promising technique for studying structures and properties of carbon nanotubes, as well as assembling and fabricating high-intensity coherent electron sources, field emission flat panel display, tips for scanning probe microscopes, new nanoelectronic devices, etc.

Focusing Properties of ThinCRT™ Display

AbstractCandescent has developed a field emission flat panel display, the ThinCRT, based on high voltage phosphors to take advantage of their high efficiency, long life, commercial availability, and wide color gamut. This paper discusses the unique system developed to focus the electrons across the 1.25 mm anode/cathode gap required for high voltage operation.

A nanotube-based field-emission flat panel display

A matrix addressable diode flat panel display has been fabricated using a carbon nanotube–epoxy composite as the electron emission source. Field-emission uniformity has been confirmed by measuring the I–V curves of pixels across the panel. This prototype display demonstrates well-lit pixels under ±150 V biasing signals. The “on” and “off” of the pixels are well controlled by the half voltage “off-pixel” method. Further improvement of this technology may lead to easy-to-make and inexpensive flat panel displays.

Silicon field emitter cathodes: Fabrication, performance, and applications

This article gives an overview of fabrication and performance of a class of vacuum microelectronic devices, namely, silicon tip-on-post field emitter arrays (FEAs). Experimental data illustrating the device performance are presented in the context of requirements for field emission flat panel display and microwave power amplifier applications. Critical geometrical parameters of the device are discussed, and a fabrication process flow designed to optimize these parameters is described. Equipment and methods for testing electrical performance of the FEAs and results thus generated are presented. Specifically, emission current versus gate voltage characteristics for arrays with tips formed using anisotropic (crystallographic–orientation–dependent) or isotropic etching techniques, uniformity of these characteristics across a 4 in. diameter substrate, stability of emission current in ultrahigh vacuum conditions, and changes in emission current upon exposure to active gases at varying pressure are discussed.

Field emission device modeling for application to flat panel displays

A computer model has been developed for determining the electrical characteristics of field emission devices. Numerical techniques are employed to determine the electric field distribution and electron trajectories in the modeled device. Using the electron trajectories and emission current density determined from the Fowler–Nordheim equation, electrode currents are found. The current–voltage characteristics are constructed using superposition of electric field solutions. Simulation results are presented for a single vertical triode of a field emission flat panel display. The cathode tip has a radius of curvature of 20 nm and is centered in a 2 μm diam gate aperture. The anode is typically biased at 400 V and spaced 0.2 mm from the cathode. Simulation results indicate turn-on at 75 V and 0.1 μA emitted at a gate drive of 95 V. Gate current is negligible. Peak-to-peak gate drive for a 1000 line field emission display having 100:1 contrast ratio is found to be less than 50 V for such a structure.