Effects of gas composition on the synthesis of boron-doped carbon nanotubes

Boron-doped carbon nanotubes ( CNTs) were synthesized on porous silicon by electron cyclotron resonance chemical vapor deposition from CH4 B2H6 and H-2 were used as the source gases and Fe3O4 nanoparticles as the catalyst. The effects of gas composition on the growth characteristics of boron-doped CNTs were investigated..Scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy were used to evaluate the structure and composition. Results show that addition of B,H, influences the growth characteristic of CNTs greatly, making CNTs bend. Increasing the amount of B2H6 leads to a structural change in the CNTs from straight tubular to bamboo-like. Outer diameter increases from 60 - 90 nm to 200 - 250 nm, tube wall thickness increases from 10 - 20 nm to 70 - 100 nm, and a rougher surface and a decreased growth rate is noted. An increase in the B/C ratio of the specimen was detected as the amount of B2H6 increased. The B/C ratio can be up to 28:72 when the B2H6/CH4 ratio is 2:1.