Effect of buffer layer nature on multiwall carbon nanotube growth rate by PECVD

Abstract

In this work, vertically aligned multiwall carbon nanotubes (MWCNTs) were produced, at 600 °C, by plasma enhanced chemical vapour deposition (PECVD), in an electron cyclotron resonance (ECR) plasma chamber using a C2H2/NH3 gas mixture. The MWCNTs were directly grown onto a carbon buffer thin film (a-C) or a titanium nitride film (TiN) deposited on a silicon surface. For this purpose, nickel (Ni) nanoparticles were deposited on the both buffer layers, by an electrochemical procedure, and used as a catalyst for the MWCNT growth. The effect of the buffer layer on MWCNT growth rate during different growth times was investigated in this work. It was found that MWCNT produced over the a-C buffer grow faster compared with those grown over the TiN buffer. Moreover, when the growth time increases, the MWCNTs deposited on the a-C buffer can maintain a relatively high density compared with those grown on the TiN layer. Using in-situ X-ray photoelectron spectroscopy, the effect of both buffers on the MWCNT growth rate is discussed with reference to changes in the state of Ni catalysts annealed at 600 °C. The results demonstrate the benefit of using the a-C layer for MWCNT grown by PECVD for specific applications including electrochemical biosensors and electrochemical capacitors.