| Carbon nanotubes (CNTs) have superior electronic and mechanical and thermodynamic properties which make them attractive in different application fields, especially in the field of flat panel display. However, up to date, field emission properties of CNTs, such as the number density of electron emission sites, the stability and uniformity of field emission current and so on, are not satisfied for its application as cold cathode electron source. It is crucial to improve the field emission properties of CNTs for their commercial applications. In this work, a series of studies were proceeded round the improvement and optimization for the fabrication processes of CNTs cathodes film and the post-treatment of the as-prepared CNTs film with the purpose of improving the field emission properties, and some useful conclusions were obtained.Based on the properties of low melting point and high conductivity, a new preparation process for carbon nanotubes(CNTs) cold cathode was studies in the first time through the replacement of traditional organic binder or Ag paste with Ag nano-particles. A flat CNTs films with good field emission performance was obtained after sintered 30 min under 250oC. The measurements reveal that the field emission properties are the best when the mass ratio of CNTs and Ag nano-particles is 1:2. Too many and too few Ag nano-particles in mixed paste all result in poor field emission properties. The fabrication process for CNTs/Ag nano-particles cathode was optimized by using a two-step coating method, The two-layer structure CNTs cathode obtained by using the two-step coating method showed improved field emission properties, which can due to the improved adhesion of CNTs to substrate.CNTs film was fabricated using electrophoresis deposition technique. The effects of various process conditions and the measurement parameters on the field emission properties of CNTs were investigated comprehensively in the first time, and the relative optimized electrophoresis process conditions and details were obtained. With the increasing of the interelectrode distance and the decreasing of the residual gas pressure in vacuum chamber, the as-prepared CNTs film exhibited improved emission current stability, while turn on electrical field and threshold electrical field became high. The probably reason causing the non-linearity phenomenon on the Fowler-Nordheim (F-N) plots was also analyzed.In order to improve the field emission properties of electrophoresis deposition CNTs film using the method of decreasing the work function of the emitterΦ, a thin Ti film was coated on the surface of CNTs cathode film. Titanium carbide with lowΦformed after annealing in vacuum chamber decreased the work functionΦof CNTs emitters, which caused the improvement of field emission properties. When the Ti film was coated on the substrate, conductive titanium carbide was also formed between CNTs and substrate after annealing. The field emission properties were improved by the existence of conductive titanium carbide which resulted in the enhancement of adhesion of CNTs on the substrate and the elimination of the interface potential barrier between CNTs and the substrate.The effects of Ar microwave plasma treatment on the microstructure and field emission properties of coated CNTs/Ag nano-particles film and electrophoresis deposition CNTs film were studied systematically. It is found that the microstructure was changed and the field emission properties were improved obviously by the plasma treatment. We attributed the improved field emission I-V property to the increase ofβand decrease of electron emission potential barrier resulted by the changed microstructure. Meanwhile, plasma treatment removed a portion of protruding CNTs emitters on the film surface, which would allow a greater number of emitters to be active with compensation for a higher electrical field application, and raised the number density of electron emission sites, which lead an improvement in emission stability and uniformity.
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