Chun Gyoo Lee

Transparent conducting ZnxCd1−xO thin films prepared by the sol-gel process

Thin films of zinc oxide, cadmium oxide, and their compounds have been deposited by the sol-gel process. The ZnO and CdO films are found to have different crystallographic structures and their compounds are found to be simple mixtures of the two different crystallographic strutures for the constituent materials. The electrical resistivity of the compounds, ZnxCd1−xO thin films decreases as the composition x decreases, so that pure CdO thin films have the lowest electrical resistivity of 3×10−3 Ωcm. Although the optical transmittance and bandgap of the ZnxCd1−xO films also decrease as the value of x decreases, all the films prepared in this study have a fairly high transmittance reproducibly in the visible spectral range at room temperature. The electrical resistivity of the films is found to have significant dependence on the post-deposition annealing environments. This dependence is more pronounced for the films which contain higher percentages of Zn among all the ZnxCd1−xO films prepared in this study. The dependence of the electrical resistivity on the aluminium impurity concentration in the ZnxCd1−xO films is also examined.

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.

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.

P‐43: A Simple Structure and Fabrication of Carbon‐Nanotube Field Emission Display

A triode structure of field emission displays based upon carbon nanotube emitters is presented. In this structure, gate electrodes are located underneath cathode electrodes with an in-between insulating layer, so called an under-gate type triode structure. The modulation of electron emission by changing gate voltages is confirmed. The advantage of simple structure and fabrication processes may lead the under-gate triode type structure to the practical applications.

20.1: Invited Paper: New Emitter Techniques for Field Emission Displays

New emitter materials for field emission displays (FEDs) have emerged and some of them faded away. Recently, carbon nanotubes have attracted much attention as a new emitter material due to their excellent field emission characteristics. We have investigated several different structures of FEDs with carbon nanotube emitters: normal gate, remote gate, and under-gate triode structures. The panels with these structures were fabricated to be a 15″ diagonal and VGA resolution. Their field emission characteristics, uniformity, and scalability are discussed in detail.

P‐53: Vacuum In‐Line Sealed CNT‐FED Fabricated by A Screen‐printing of Photo‐sensitive CNT Paste

A carbon nanotube field emission display(CNT FED) panel with a 2 inch diagonal size was fabricated by 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 20nm. The sealing temperature of the panel was around 390 °C and the vacuum level was obtained with 1.4×10−5 torr at the sealing. The field emission properties of the diode type CNT FED panel were characterized. Now, we are developing a triode type CNT FED with a self-aligned gate-emitter structure.

Vacuum in‐line sealing technology of the screen‐printed CNT‐FEA

Abstract We have fabricated a carbon nanotube field emission display (CNT‐FED) panel with a 2‐inch diagonal size by using a screen printing method and vacuum in‐line sealing technology. The sealing temperature of the panel was around 390 °C and the vacuum level was obtained with 1.4×10‐5torr at the sealing. When the field emission properties of a fabricated and sealed CNT‐FED panel were characterized and compared with those of the unsealed panel which was located in a test chamber of vacuum level similar with the sealed panel. As a result, the sealed panel showed similar I‐V characteristics with unsealed one and uniform light emission with very high brightness at a current density of 243 μA/cm2, obtained at the electric field of 10 V/μm.

Triode‐type field emission displays with carbon nanotube emitters

Abstract Carbon nanotube emitters, prepared by screen printing, have demonstrated a great potential towards low‐cost, large‐area field emission displays. Carbon nanotube paste, essential to the screen printing technology, was formulated to exhibit low threshold electric fields as well as an emission uniformity over a large area. Two different types of triode structures, normal gate and undergate, have been investigated, leading us to the optimal structure designing. These carbon nanotube FEDs demonstrated color separation and high brightness over 300 cd/m2 at a video‐speed operation of moving images. Our recent developments are discussed in details.

Screen printed carbon nanotube field emitter array for lighting source application

Photosensitive carbon nanotube (CNT) paste was synthesized with spin on glass (SOG) as inorganic binder. The field emission characteristics of this CNT paste was studied. CNT field emitter arrays (FEAs) was then fabricated using screen-printing method, photolithography and vacuum-in-line sealing technology. It is concluded that the diode type FEA using CNT paste with SOG can be used for lighting system applications such as the back light unit in TFT-LCD.