Influence of the gas composition on the synthesis of boron-doped carbon nanotubes by ECR-CVD

Abstract

Boron-doped carbon nanotubes (CNTs) were synthesized on porous silicon by electron cyclotron resonance chemical vapor deposition (ECR-CVD). CH 4, B 2H 6 and H 2 were used as the source gases and Fe 3O 4 nanoparticles as the catalyst. The effect of gas composition on the boron-doped CNTs growth characteristic was investigated. Scanning electron microscopy , transmission electron microscopy and X-ray photoelectron spectroscopy were used to evaluate the structure and composition. The results show that adding B 2H 6 influences the growth characteristic of CNTs greatly. CNTs tend to unaligned growth with boron. The increase of the B 2H 6 ratio leads to changes in the structure of CNTs from straight tubular to bamboo-like and makes the outer diameters bigger, the tube walls thicker, cause a rough surface and a decrease in the growth rate of the CNTs. An increase in the B/C ratio within the samples was detected as the B 2H 6 ratio in the precursor gas was increased.