Yu-Ying Hsu

Carbon-Nanotube-Based Field Emission Devices with a Self-Focusing Gate Structure

Carbon nanotubes CNTs have attracted much attention for application in field emission displays FEDs due to their high geometric aspect ratios, chemical inertness, and excellent emission capacity. 1-3 Two types of operation configurations have been demonstrated in recent years: diode and triode. The triode-type configuration seems to be a promising candidate because of its better driving ability in low-voltage operation. 4-6 Several triode-type device structures have been proposed, including normal gate, under gate, and side gate structures, and the normal gate structure seems to be more promising in terms of low operation voltages as well as device performance. 7-11 For application to FEDs, a high anode voltage is essential for high efficiency of the phosphor, high brightness, and color purity. The high anode voltage requires a large vacuum gap between the cathode and anode plates so as to avoid the problem of arcing. Accordingly, the large vacuum gap may give rise to an issue of electron-beam spreading, which would cause cross talk between adjacent pixels and would deteriorate the resolution of displays. Therefore, a focusing structure which could effectively control the trajectory of electrons and reduce the cross-talk noise is necessary. Several focusing structures of FEDs have been announced to overcome the issue of electron-beam spreading, such as the planar electrode, 12 double-gate, 13 and mesh-electrode structures. 14 Those structures have some drawbacks, however, such as manufacturing complexity and reduction in emission current due to the focusing electrodes. In this work, CNT-based field emission devices with a selffocusing gate structure are proposed which do not require additional focusing electrodes as compared with other structures. The results of the simulation and luminescent images reveal good control of electron trajectory with this self-focusing structure, effectively reducing the spot size on the anode plate. Therefore, the focusing structure combined with simple processes is promising for application in FEDs.

Low efficiency droop of InGaN/GaN blue LEDs with super-lattice active structure

Department of Photonics & Institute of Electro-Optical Engineering, National Chiao Tung University, 1001 Ta Hsueh Rd., Hsinchu 300, Taiwan R&D Division, Epistar Co. Ltd., Science-based Industrial Park, Hsinchu 300, Taiwan Department of Electronic Engineering, National Chiao Tung University, 1001 Ta Hsueh Rd., Hsinchu 300, Taiwan Institute of Lighting and Energy Photonics, National Chiao Tung University at Tainan, Taiwan Phone: +886-3-5712121, Fax: +886-3-5716631, E-mail: SPC@epistar.com.tw

7.2: Carbon Nanotubes Synthesized at Low Temperature and a Novel Self‐Focusing Gated Field Emission Device

A method for synthesis of CNTs at low temperature using thermal CVD is proposed. A multi-layered catalyst, Co/Ti/Al, has been successfully utilized to synthesize carbon nanotubes at 500°C by thermal CVD via modifying the flow rate of reaction gases. The flow rates of ethylene, hydrogen, and nitrogen are determined to be 125, 10, and 1000 sccm to improve the growth and field emission characteristics of CNTs at low temperature. Moreover, a novel self-focusing gated device was proposed to resolve the problem of electron beam divergence.