Fabrication and field emission properties of carbon nanotube implanted metal aanocomposite

Abstract

Carbon nanotubes have high aspect ratio, small radius of curvature, high electrical and thermal conductivity, high mechanical strength, high chemical stability and low work function, thus, they have emerged as the most promising field emitter materials for application in field emission displays. In order to fabricate carbon nanotube-based field emission displays (CNT-FED), several approaches were proposed during the last decade but low yield of carbon nanotube emitters, weak bonding between carbon nanotube and metal substrate and difficulty in large area synthesis are the key technological issues still to be solved. In this study, it was shown that carbon nanotube reinforced metal composite powders can be fabricated by chemical route and that these powders can be further processed to make carbon nanotubes implanted metal cathodes for large area field emission displays. According to the growth behavior of each type of metal on the surfaces of carbon nanotubes, several different morphologies can be fabricated by using Co, Ni and Cu. Carbon nanotube implanted Co cathode was fabricated from carbon nanotube implanted Co composite powders by simple screen printing process followed by heat treatment. Some part of carbon nanotubes are protruding out from the metal layer with some part of carbon nanotubes implanted in the metal layer with sound interfacial bonding. A diode structure was fabricated and the field emission measurements strongly suggest that the carbon nanotube implanted Co cathode is an excellent field emitter with low turn-on electric field, high current density and excellent reliability. The metal layer provides high electric conductivity from substrate to carbon nanotube and reliable supporting media so that the carbon nanotubes do not detach from the substrate, thus, many of the technological issues of CNT-FED can be solved.