Effects of post treatment on the field emission properties of CNTs grown by ECR-CVD

Field emission display (FED) has been considered as one of the most promising application of carbon nanotubes. In FED application, the CVD assisted grown CNT cathodes have major problems, i.e., the screen effect of the well aligned CNT array reduces the field emission characteristics. The post treatments for cathode become necessary to improve the field emission characteristics and uniformity of the CNT emitters. In this study, well-aligned carbon nanotube array on Si substrate were synthesized by using a catalyst-assisted microwave plasma electron cyclotron resonance chemical vapor deposition (ECR-CVD) system with methane as source gas. Then a series of post treatment, including hydrogen plasma, oxygen plasma and electroless nickel plating, were conducted on the as grown CNT arrays. The results show that the H-plasma may damage the stems of CNTs at longer etching time. Consequently, the field emission characteristic of CNTs is reduced. In contrast, oxygen plasma increases the field emission characteristic of CNTs by reducing CNTs diameter and increasing inter-tube distance. Comparing to plasma post-treatment, electroless nickel-plating post-treatment is apparently improve the field emission characteristic of CNTs. This process results in the gathering of nickel catalysts at the top of CNTs and concentration CNTs field emission ability.