电泳方向对碳纳米管薄膜及场发射特性影响

Influence of Electrophoretic Direction on the Morphology and Field Emission Properties of Carbon Nanotube Film

电泳法是制作碳纳米管(Carbon nanotubes-CNTs)场发射冷阴极的重要方法.研究发现,不同电泳方向会对碳纳米管薄膜表面形貌产生影响.电泳电极竖直放置,沉积的碳管薄膜表面均匀性好,但碳管取向性差,场发射特性一般.电极水平放置,碳纳米管与玻璃衬底成倾斜状,沉积的薄膜各碳管互相缠绕,具有一定取向性,提高了碳纳米管的场增强因子,改变发射体的表面功函数,显示出比电极竖直放置更好的场发射特性.此外,电极水平放置且阴极在上时,CNTs取向性和场发射特性较其它放置方法更好.

Electrophoretic deposition technique is an essential method for producing CNT cold cathodes.Research shows that electrophoretic direction affects the surface morphology of thin films of CNTs.An electrode vertically placed in electrophoretic deposition produces a good uniform surface but a poor CNT orientation and a moderate field emission property.An electrode horizontally placed in electrophoretic deposition makes CNTs lean against the glass substrate and twin with each other,thus producing a better field emission property because the field enhancement factor of CNTs has been improved and the work-function of emitter changed.However,the surface orientation of CNTs is inferior to that in the previous method.Furthermore,in the case of a horizontal electrode with the cathode upwards,the orientation and field emission property of cathode electrode are better than those in other placement methods.