Based On Carbon Nanotube Fed Cathode Preparation And Their Field Emission Properties

FED possess many advantages such as high definition,low power consumption,high brightness,fast response time,wide work temperature range low cost.and so on Carbon nanotubes tubes(CNTs) have been studied extensively as cold cathodes for field emission display(FED) due to their high aspect ratio,small tip radio of curvature,and high conductivity. Despite several outstanding chemical and physical properties inherent to CNTs,there are few reports on the actual devices fabricated with CNT as a base material.This is in part attributed to the fact that bare CNTs alone cannot satisfy all requirements of actual applications.As a result,considerable efforts have been directed toward tailoring electrical and mechanical properties of CNTs through various methods.The solution to these problems will speed up the industrialization of the field emission devices based on CNTs and raise the market competition ability.CNTs cathodes are commonly prepared in two ways:in situ CNTs growth directly on the catalyst patterned substrate by chemical vapor deposition(CVD),and Screen-Printing of CNTs paste on electrodes- patterned glass.In the study,the two methods are both applied to systemically study.The CNTs film cathodes are grown on Fe catalyst on different substrate using chemical vapor deposition method.Screen-printing and coating methods are used to prepare the CNTs film cathodes and the emission properties of cathodes are improved by laser dealing and doping or coating metal methods.This thesis included following contents:1 The CNTs are synthesized on Fe and Ni catalyst using CVD method.The results show that the MWCNTs synthesized on Fe catalyst are intertwined heavily and uneven distribution compared with MWCNTs prepared on Ni catalyst.2 The CNTs are grown on Fe catalyst on different substrate using CVD method.The results show that the problem of intertwinement and uneven distribution are solved commendably.3.The field emission characteristics of MWCNTs film on different substrate arc also studied.The emission of MWCNTs film on quartz substrate appears outstanding with low turn-on voltage,large current and good stability.4 We develop the coated method to prepare the cathode of FED based on screen-printed method.After comparison we found that the cathode prepared by coated method is better than screen-printed in field emission performance,whereas the current is not enough to be stable. 5.The field emission performance is obviously improved after laser treatment and deposition a thin layer of titanium on MWCNTs film.The turn-on voltage evidently decreases. The current increase significantly and has long time stability.