Hydrogen Plasma Pretreatment on Field Emission Properties of MultiWalled Carbon Nanotubes Grown by Microwave PECVD

Abstract

The morphology and electron emission characteristics of multiwalled carbon nanotubes (CNTs) fabricated by microwave plasma-enhanced chemical vapor deposition (PECVD) were examined. Prior to the growth of CNTs, TiN and Ni were deposited in succession as a diffusion barrier and a catalyst layer, respectively, and hydrogen plasma pretreatment was carried out to form Ni nanoclusters. The growth of CNTs was performed using the mixture gas of and at low temperature of 500°C. The impact of hydrogen plasma pretreatment on the structure and emission properties of the CNTs was investigated. It was confirmed that the average diameter of CNTs could be easily controlled by hydrogen plasma pretreatment, and diameters were varied from 36 to 26 nm as pretreatment times were changed from 5 to 15 min. However, further increase of the pretreatment time gave rise to rapid decrease in CNT growth. After 25 min of plasma pretreatment time, scanning electron microscopy observation exhibited destruction of the CNTs. In addition, variation of CNT diameter due to the plasma pretreatment caused a drastic change in emission properties. The turn-on voltages of CNT emitters in a diode-type electron emission configuration were varied from 3.5 to 9 V/μm according to the hydrogen plasma pretreatment conditions. The close relationship between electron emission characteristics and pretreatment time indicates that pretreatment condition can be a key process parameter in CNT growth for field emission displays and should be optimized. © 2004 The Electrochemical Society. All rights reserved.