Field emission from metal-containing amorphous carbon composite films

Metal-containing (Co, Al and Ti) amorphous carbon composite films (a-C:Me) have been prepared by the filtered cathodic arc technique using metal-containing graphite targets at room temperature. Field emission properties of the heat-treated a-C:Me films were improved and were found to be dependent on the metal content and variety of metals. After heat-treatment at 550°C in a mixture of acetylene and nitrogen gases, the field emission properties of a-C:Co films were significantly improved, in which Co acted as catalysts to enhance graphitization as well as formation of carbon nanotubes during heat-treatment. A threshold electric field of less than 2 V/μm was obtained from the heat-treated a-C:Co composite films without conditioning. The heat-treated a-C:Al and a-C:Ti films, though the conditioning step could be avoided and relatively low threshold fields could be obtained, exhibited relatively low emission site densities, however. The a-C:Me films, which can be deposited with a high rate at room temperature and require a relatively low temperature, heat-treatment process to enhance electron emission, are promising for practical applications in field emission display.