Hyun-Kyu Lee

A field-emission display with a self-focus cathode electrode

A field-emission display (5-in.) using thick-film carbon nanotube emitters is fabricated. A thick-film insulating layer and an emitter layer are employed for low-cost manufacturing and scalability to a large panel. A self-focus cathode for this display is proposed. An auxiliary electrode in contact with the cathode electrode surrounds the emitter layer at the center of gate aperture. The structure has several advantages in manufacturing. According to simulation results, this self-focus cathode structure shows excellent focusing effects in spite of its simple manufacturing process and structure.

Triode-type field emission array using carbon nanotubes and a conducting polymer composite prepared by electrochemical polymerization

We report a method to fabricate carbon nanotubes (CNT)/conducting polymer composite films for the application of CNTs to field emission displays. The composite was prepared by a combination of electrochemical polymerization of pyrrole and electrophoretic deposition of CNTs. We obtained a uniform CNT/conducting polypyrrole polymer composite film. The CNTs were mainly coated on protrusions of the polypyrrole film and emitted electrons without rubbing and stretching. We realized a triode-type field emission array (FEA) using the CNT/polypyrrol composite. This FEA showed that the emission current was modulated by gate voltage of 30 V. The film morphology and emission characteristics of the CNT/conducting polymer composite were studied using optical microscopy, scanning electron microscopy, and an emission test in vacuum.

An 80nm 4Gb/s/pin 32b 512Mb GDDR4 Graphics DRAM with Low-Power and Low-Noise Data-Bus Inversion

A 4Gb/s/pin 32b parallel 512Mb GDDR4 SDRAM is implemented in an 80nm DRAM process. It employs a data-bus inversion coding scheme with an analog majority voter insensitive to mismatch, which reduces peak-to-peak jitter by 21 ps and voltage fluctuation by 68mV. A dual duty-cycle corrector is proposed to average duty error, and tuning is added to the auto-calibration of driver and termination impedance.

Development of triode-type carbon nanotube field-emitter arrays with suppression of diode emission by forming electroplated Ni wall structure

Triode-type field-emitter arrays were developed by screen printing a photosensitive paste including single-walled carbon nanotubes. Ni wall structure (NWS) was electroplated to form a thick gate to suppress diode emission induced by strong electric strengths due to an anode potential and to focus electron beams to their destined color subpixels. It was observed in computer simulations, as well in experiments that the NWS with the optimum thickness was effective in reducing the diode emission and enhancing electron-beam focusing by modifying electrical potentials around the carbon nanotube emitters. Our fully sealed field-emission display panel using the field-emitter arrays with the NWS demonstrated full color moving images without serious diode emission and with satisfactory color separation.

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.

39.2: The Full‐Color Video Images with Uniquely‐Gated Carbon Nano‐tube Field Emission Displays

Thick-film printing processes have been applied for preparing a carbon nanotube field emission display (c-FED), which has a strong cost advantage for large-size flat panel display. For practical display applications, two types of the gated cathode structure named the normal-gate cathode and the under-gate cathode have been developed and improved. The normal-gate and the under-gate cathode structures have the driving voltages of ±35 V and ±65 V, respectively. The 5″ c-FED panel with the normal-gate cathode and the 7″ c-FED panel with the under-gate cathode were successfully implemented and excellent full-color video images were obtained.

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.

Positive resist for KrF excimer laser lithography

In order to develop a new positive-tone, chemically amplified photoresist for 248 nm lithography, a copolymer containing acrylic silicon moiety was synthesized. The copolymer of 1,3-bis(trimethylsilyl)isopropyl methacrylate and 4-hydroxystyrene was prepared by free radical polymerization. The polymer structure, properties and acid catalyzed deprotection were evaluated by 1H nuclear magnetic resonance, Fourier transform infrared, UV, thermogravimetric analysis and gel permeation chromatography. This polymer is thermally stable up to 150 °C and is suitably transparent at the KrF laser output wavelength (248 nm). The lithographic evaluation shows the capability of 0.28 μm resolution using a KrF excimer laser stepper.

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.