The Influences of H2Plasma Pretreatment on the Growth of Vertically Aligned Carbon Nanotubes by Microwave Plasma Chemical Vapor Deposition

Sheng-Rui Jian,Chih-Feng Wang,Wei-Ming Chiu,Hua-Chiang Wen,Chu-Shou Yang,Yuan-Tsung Chen

doi:10.1007/s11671-008-9141-5

Abstract

The effects of H2flow rate during plasma pretreatment on synthesizing the multiwalled carbon nanotubes (MWCNTs) by using the microwave plasma chemical vapor deposition are investigated in this study. A H2and CH4gas mixture with a 9:1 ratio was used as a precursor for the synthesis of MWCNT on Ni-coated TaN/Si(100) substrates. The structure and composition of Ni catalyst nanoparticles were investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The present findings showed that denser Ni catalyst nanoparticles and more vertically aligned MWCNTs could be effectively achieved at higher flow rates. From Raman results, we found that the intensity ratio of G and D bands (ID/IG) decreases with an increasing flow rate. In addition, TEM results suggest that H2plasma pretreatment can effectively reduce the amorphous carbon and carbonaceous particles. As a result, the pretreatment plays a crucial role in modifying the obtained MWCNTs structures.

Highlights

Carbon nanotubes (CNTs) [1] undoubtedly occupy a unique position among advanced materials because of its novel electrical, mechanical, and chemical characteristics [2,3,4]
It is clearly observed that higher H2 flow rate during plasma pretreatment lead to denser Ni catalyst nanoparticles
scanning electron microscopy (SEM) observations confirm that the H2 plasma pretreatment plays an important role in promoting the uniform formation of Ni nanoparticles

Summary

Introduction

Carbon nanotubes (CNTs) [1] undoubtedly occupy a unique position among advanced materials because of its novel electrical, mechanical, and chemical characteristics [2,3,4]. The effects of H2 flow rate during plasma pretreatment on the synthesis of MWCNTs on a Ni/TaN/Si substrate by using a microwave plasma chemical vapor deposition (MPCVD) system are investigated.

Results

Conclusion