碳纳米管场发射冷阴极的低温制备及场发射性能

Preparation by a Low Temperature Method and the Field Emission Properties of Carbon Nanotube Cold Cathodes

利用纳米银的低温熔接性和良好导电性,研究了以纳米银取代传统的有机粘结剂和导电银浆制备CNTs场发射冷阴极的新工艺.将CNTs、纳米银、粘性松油醇和有机溶剂混合研磨后涂敷在镀Cu玻璃基片上,250℃烧结30min后,纳米银颗粒之间互相熔接,将周围的CNTs粘结成为整体膜,形成了表面平整、导电性和场发射性能良好的CNTs阴极.测量了不同纳米银掺入量的CNTs阴极的场发射性能,结果表明:当CNTs∶Ag质量比率为1∶1时,CNTs阴极具有最好的场发射性能,阈值电场为4·9V/μm,当电场强度为5·7V/μm时,场发射电流密度为41mA/cm2.纳米银比例过大,烧结后CNTs被熔接的银膜覆盖,高电压时场发射电流明显下降,而纳米银掺入量太少则会导致CNTs阴极的附着力和导电性变差.

We study a new preparation process for carbon nanotube （CNT） cold cathode, making use of the properties of low melting point and high conductivity. In this new process, the traditional organic binder or Ag paste is replaced with Ag nanoparticles.A mixture paste of CNT, Ag nano-particles, and other organic solvents is spread on Cu-coated glass substrate. Through the melting and connecting of Ag nano-particles after sintering for 30min at 250℃ ,a flat CNT film with good field emission performance is obtained. Measurements reveal that the field emission properties are the best when CNT ： Ag mass ratio is 1 ： 1, with a threshold electric field of 4.9V/μm and an emission current density of 41mA/cm^2 at 5.7V/μm. Too many Ag nano-particles in the mixed paste result in a noticeable decrease of the emission current at high voltages because of the coating CNT by the melting of Ag films. On the other hand, poor adhesion to the substrate and electric conductivity of the CNT cathode result when there are too few Ag nano-particles.