Carbon nanotubes(CNT) prepared as an ideal material for field emission cold cathode,has many advantages such as stable chemical properties, high field emission current density etc.Carbon nanotubes have an important purpose is that it can be used for electron source of high power microwave tube. In this paper we are using three kinds of methods whichi is plasma enhancement deposition, screen printing method and electrophoretic deposition to prepare carbon nanotube cold cathode samples, and the field emission equipment to test the field emission properties of carbon nanotube cathode of each sample, and analyze the field emission results.This paper use the plasma enhancement chemical vapor deposition method(PECVD method) to prepare carbon nanotube cold cathode samples.In order to plate iron catalyst particles for growth of CNT by PECVD methode in the substrate,we used electrophoretic deposition, electron beam evaporation method respectively in the Ni film, Si film coated with a layer of iron catalyst granular layer. Carbon nanotube cold cathode samples of PECVD were prepared by using the scanning electron microscope were characterized by SEM, Raman spectra analysis of PECVD growth of carbon nanotube defect and tested on their field emission properties. By comparing the SEM photos, we found that the uniformity of electron beam evaporation plating iron grown CNT than the electrophoretic deposition method to grow the CNT much better. By comparing the field emission test results, we found that the growth of carbon nanotubes have a great effect on the field emission properties. Carbon nanotube cold cathode samples we prepared by PECVD method on the field emission test, test to obtain the maximum emission current density is 141mA/cm2, the field emission area with diameter of 3mm.This paper also use the screen printing method and electrophoretic deposition method to prepare carbon nanotubes cathode samples with large area emission region in Si substrate. Because these two kinds of methods are transplantation method, the field emission current density is small compared with the carbon nanotube cathode samples grown by PECVD directly, but has the advantages of low cost, simple process and can get the sample of carbon nanotube cathode emission area. Fabrication of carbon nanotube cold cathode samples using screen printing method, we study the different milling time, different organic material proportion in changing the field emission properties of carbon nanotube cold cathode samples and analyze its causes.Fabrication of carbon nanotube cold cathode samples using the electrophoretic deposition method, we studied the different time used in electrophoresis experiment in changing the field emission properties of carbon nanotubes cold cathode and analyze its causes. |