Carbon nanotubes (CNTs) have excellent field emission properties but there are critical problems to be solved in order to use CNTs as high performance field emitters in various application areas. Application of CNT field emitters can be categorized into two areas. One category is planar applications which use array type CNT field emitters such as FED and BLU. The other category is point electron source applications which use tip type CNT field Emitters such as X-ray tube and electron microscopy.
Thus, CNT field emitters should be designed carefully according to the specific applications. In case of array type CNT field emitters for FED and BLU, the critical issues are stability and uniformity at large area. On the other hand, in case of tip type CNT field emitters for X-ray tube, the critical issues are high resolution and stability. Based on these requirements, different research strategies were suggested and different types of materials were fabricated and characterized. For the array type CNT field emitters, CNT nanocomposite powders were fabricated by molecular level mixing process and in-situ spray coating process was developed. For the tip type CNT field emitters, CNT yarn was fabricated and its properties were investigated.
For the array type CNT field emitters, CNT/Co nanocomposite powders were successfully fabricated by polyol process and in-situ spray coating process. CNT/Co nanocomposite powders showed necklace type structure with small size distribution. CNT/Co nanocomposite field emitters by in-situ spray coating process showed better field emission properties in terms of turn-on field and stability compared to the screen printed one. The enhanced field emission properties were attributed to the self-activation of CNTs and minimized destruction of CNTs. Thus, the in-situ spray coating process is quite promising for fabrication of high performance field emitter based on CNT/Metal nanocomposites.
In order to solve problems of CNT/Co nanocompos...