The role of hydroxyl and atomic oxygen in multiwall carbon nanotube growth

Abstract

Multiwall carbon nanotubes (CNTs) were grown by the plasma-enhanced chemical vapor deposition (PECVD) method in downstream on the p-Si (100) substrate. Besides precursors, methane as the carbon source and hydrogen as the ablation, oxygen or H₂O was alternatively inlet into the reactive chamber at the pressure of 0.05 MPa. Given characterizations of the tube structure and tube mass weight, the role of radical atomic O, hydroxyl and perhydroxyl in multiwall CNT growth was explored. In addition to a small amount of O₂ (∼0.67%) or H₂O (∼0.1%), it was found that a high quantity of pure nanotubes can be grown in the downstream. However, no nanotube could be formed or even the carbon matrix generated when the concentration of O₂ or H₂O exceeded a proper value in the mixture. The mechanism of multiwall CNT growth controlled by active radicals was explored in this paper.

Keywords

nanotubes / plasma enhanced chemical vapor deposition (PECVD) / water, hydroxyl / mechanism