Effects of High Density Plasma Post Treatments on the Characteristics of Carbon Nanotube Field Emission Displays

• Main Authors: Wen-Pin Wang, 王文彬
• Other Authors: Huang-Chung Cheng
• Format: Others
• Language: en_US
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/14343950955167564206

碩士 === 國立交通大學 === 電機資訊學院碩士在職專班 === 93 === Carbon nanotubes (CNTs) have been applied for the process of the field emission devices, because of their high aspect ratio, small radius curvature , high chemical stability, and high mechanical strength. Field emission current of CNT arrays depends strongly on the work function and geometry of the surface of CNT arrays. Excellent field emission properties of CNTs have been demonstrated lower turn-on electric field and higher filed emission current density. For the synthesis of field emission materials, carbon nanotubes (CNTs) with various morphologies have been synthesized using thermal chemical vapor deposition (Thermal CVD) with Fe-Ni alloy catalysts via controlling the parameters of CNTs growth. The CNT emission arrays showed excellent field emission properties, however, the field emission properties of the high density CNTs (~1012/cm2) degraded for the screening effect of the electric field. To improve the field emission properties of the CNTs, a novel post treatment process with plasma etching to reduce the screening effect of the electric field have been proposed. The results depicted that the field emission properties can be upgraded with proper high density plasma treatment conditions. A plasma post treatment was introduced to reduce the density of CNTs. Scanning electron microscopy (SEM) micrographs showed reduced densities of the CNTs, and the measurement of electrical characteristics revealed the improved field emission properties under suitable plasma conditions. The turn-on electrical field decreased from 3.1 V/um to 2.2 V/um, and the emission current density increased from 2.35 mA/cm2 to 48 mA/cm2 at the applied field of 5 V/�慆. SEM have verified that the distribution and surface morphology of CNTs have been changed by HDPPT (argon , oxygen ). The plasma exposure to argon (Ar) gas was performed in situ in order to modify all structural defects (non-crystalline carbon) and contamination of CNTs . Oxygen plasma removed the structure of carbon nanotubes on the surface, such as removing amorphous carbon, exhibiting the open-end on the tip and reducing the walls of carbon nanotube by way of chemical reaction, produce CO , CO2 volatility gas and influence density of CNTs. Finally, the CNT triode structures with the proposed plasma post treatments have been demonstrated to achieve the low voltage at 18V.