A one step approach to B-doped single-walled carbon nanotubes

Abstract

Tailoring the electronic properties of single-walled carbon nanotubes by chemical modification through incorporation of heteroatoms within the tube walls represents a key method for the applicability of these structures in semiconductor technology. For p-type doping experimental studies on the synthesis of B doped single-walled carbon nanotubes have been reported using substitution reactions, arc discharge and laser ablation. However, synthesis using the up-scalability of the widely used chemical vapor deposition approach has not been successful so far. In this work, we present an enhanced CVD approach using high vacuum and promoting the use of solely one liquid precursor containing B and C to synthesize B-doped single walled nanotubes with unique characteristics on the subject of controlled “low doping”. In comparison to non-doped single-walled carbon nanotubes, these tubes have exceptional stability. From Raman and TEM we observe a very low defect concentration concomitant with small nanotube bundles containing 3 to 5 tubes with a narrow diameter distribution (0.9 to 1.5 nm). The defect concentration is significantly lower than in pure carbon nanotube reference samples. The overall B content and the bonding environment of the incorporated B were probed in detail for the first time by XPS. We identified different B bonding environments at less than 1 at%. This highlights the applicability of a rigid band model improving the accessibility of these tubes with controlled p-type doping in nano- and optoelectronic devices.