电泳工艺制备阵列场发射阴极及其性能的研究

Preparation and Field Emission Properties of Patterned Carbon Nanotubes Cathode by Electrophoretic Deposition

碳纳米管是理想的场发射冷阴极材料,阴极的图形阵列化是实现碳纳米管场发射显示器动态全彩视频显示的核心。三极管结构能够更好地进行矩阵寻址显示图像,且与常规的驱动电路相兼容,降低整体平板显示器件的制作成本。从实验出发,探索利用简单的电泳工艺制备图形化碳基薄膜阴极,采用与阴极成同一水平面的栅极的三极管结构,并对电泳的实验参数进行优化以提高阴极电压电流特性和发射的均匀性等问题,为场发射器件的制造提供优良的工艺基础。研究机械球磨和稀释悬浊液浓度对碳纳米管沉积均匀性的影响。实验结果表明稀薄的悬浊液的条件下可以在玻璃的银浆导电层上沉积较薄而均匀的碳纳米管膜,与丝网印刷工艺制备的阴极相比,均匀性更好,厚度更容易控制,具有更好的发射均匀性。测试图形化的阵列碳纳米阴极的三极管结构的场发射特性,发现当阳极电压保持在600V,栅极电压接近500V时,阳极电流能达到2.6mA/cm2。荧光粉发光均匀,相比二极管结构具有更低的阈值电压,在亮度、均匀性和稳定性方面都有显著的优势。

Due to the high conductivity, large ratio of length and diameter, high mechanical intensity and the chemical stability of carbon nanotube, carbon nanotubes have been considered as the excellent cold cathode material of field emission, and carbon nanotnbes have been researching to apply in diverse areas such as field emission display, light source, sensor and so on. In this paper, patterned cathode electrode was prepared by screen-printing, then the carbon nanotube film was deposited onto the patterned substrate by electrophoretic deposition. The field emission properties of as-grown cathode were also studied. The effect of ball milling and solution concentration were investigated to improve the uniformity of deposited CNTs film. For lower threshold voltage of field emission, the properties of ＂triode structure＂ and ＂diode structure＂ was compared. It was obvious that ＂triode structure＂ has the lower threshold voltage and better brightness. The experiment showed that electrophoretic deposition is a good approach to preparing the cold cathode of field emission. Comparing other preparation of patterned cold cathode, such as the screen-painting, optical lithography, electrophoretic deposition has its merit in controlling, low cost, simplicity. Accordingly, it will be a valuable option to prepare the patterned cold cathode. Moreover, the triode structure is an effective method to low the threshold voltage of field emission.