N. S. Park

Electrophoresis deposition of carbon nanotubes for triode-type field emission display

A triode-type field emission display has been fabricated using carbon nanotube emitters. Purified single walled carbon nanotubes were selectively deposited onto a cathode electrode in a triode-type structure by an electrophoresis. Emission current was modulated with gate potentials of 100–300 V. A high brightness of 1000 cd/m2 with uniform emission was obtained at 900 V at the anode and 200 V at the gate. The fluctuation of emission current was found to be less than 5% in a fully sealed field emission display. Selective deposition of carbon nanotubes by electrophoresis shows high feasibility for triode-type field emission displays.

Five inch full color field emission displays with narrow gap studies

Electron beam spreading and emission current density for different shapes of microtips with bias levels are simulated for the application of high voltage or low voltage phosphors. In the simulation, the morphology of micro tips and the structural parameters of a field emission display (FED) panel are optimized in the direction of enhancing panel brightness as well as avoiding cross talk between pixels. Field emitter arrays with the optimized shape of microtips were fabricated for the application to real devices. Three different technologies for phosphor screening, electrophoresis, printing, and slurry methods, are evaluated in terms of white color coordination of screened phosphor plates in a FED panel level, leading to the selection of the best screening process for FEDs. The charging effect of phosphor surface seems to have an effect on the luminance properties of phosphors, which can be suppressed with a drive circuitry in the real FED operation. It is observed that electron beam irradiation triggers s...

Fabrication of Spindt-type tungsten microtip field emitter arrays with optimized aluminum parting layers

Spindt-type field emitter arrays of tungsten microtips have been fabricated by optimizing aluminum parting layers. The aluminum parting layers, which play a crucial role in the subsequent deposition of peeling-free tungsten films, are characterized by varying the deposition conditions. The aluminum parting layer deposited at a high vacuum level has a good stress relaxation effect, and tungsten microtip field emitter arrays, free of peeling, are successfully fabricated and show good electrical characteristics.

Improved performance of nonevaporable getter activated by a continuous wave infrared laser

We demonstrate a simple and efficient activation method of nonevaporable getter where a local heating is provided by a laser source. Dependence of various parameters such as laser power, scan speed, and irradiation time by the degree of getter activation was experimentally examined in detail. It is shown that the laser irradiation enhances the getter activation process considerably by shortening the time and increasing the gas absorption capacity required to achieve a desired vacuum level for flat panel display application. The degree of laser activation is compared to that of the conventional thermal heating method. Under the optimized activation conditions, we achieved a vacuum level of 2×10−6u200aTorr from the initial value of 4×10−4u200aTorr. Therefore, the laser irradiation method is a very promising technology for nonevaporable getter activation which overcomes a number of problems resulting from the conventional method.

Integration of high voltage field emission display followed by macro- and nanostructural analysis on microtip

For resolving electron beam focusing and electric field breakdown between the anode and cathode plates in a high voltage field emission display (FED), the metal mesh grids are adapted in one body with spacers. The spacer charging mechanism is modeled in the real panel domain and confirmed by experiment. We analyze the morphology and the chemical composition modifications of the microtips in the narrow vacuum gap of a 5.2 in. FED panel, and infer possible degradation mechanisms in a FED device from our experimental data. The degree of oxidation formed on the microtip surface during fabrication and device operation is studied. Gas aging method for suppressing oxidation on the microtips and stabilizing phosphor is implemented for our 5.2 in. high voltage FED.

Structural and process characterization of high voltage operated field emission displays with focus electrodes

Focus electrodes are engaged to improve focusing characteristics of electron beams in 5.2 in. high voltage field emission displays. It is observed experimentally that the electron beam is collimated fairly well on an optimal condition, which is also compared with simulation results. The layout of ceramic spacers is optimized experimentally as well as by simulations. We uniquely develop a carrier gas of Ar and 1.5% H2, which is effective in prohibiting deterioration of device performance during thermal sealing. A luminance in excess of 400 cd/m2 is achieved at an anode voltage of 5000 V. A video running full color image is successfully demonstrated.

Studies of full color field emission display core technologies with the electrical and structural analysis

Electron beam spreading and its relationship with layout of field emission display (FED) is simulated and discussed. The morphological optimization of microtips is introduced for the effect of field enhancement with the process condition. The structural effect of thin film step coverage which is formed during the fabrication of field emitter arrays (FEAs) is uniquely studied with the reliability of FED. The surface condition of phosphor and its relationship with the brightness enhancement are analyzed and studied with the specific aging step. A unique approach of gas aging for the image stabilization is introduced and fully analyzed.

Mechanical and structural characterization of ceramic spacers with a high aspect ratio for 5.2 in. field emission displays

Ceramic spacers with a high aspect ratio (80 μm/1.1 mm) were fabricated and laid out in a high voltage 5.2 in. field emission display (FED) panel. Alumina was chosen as spacer material and sintered at 1600u200a°C for high mechanical strength and suitable electric resistivity. Three different types of spacers, single-trench type, double-trench type, and honey-comb types, were considered in this study. We optimized the structure and the layout of spacers in terms of stress distributions, build up profiles of glass, carrier gas flows inside a panel. Among the three different types of spacers, the double-trench structure spacer provided the most uniform gas flow and the highest mechanical strength. The optimal number of spacers with 80 μm width and 1.1 mm height was found to be 7 for an uniform stress distribution in a 5.2 in. FED panel by experiments and computer simulations.