Boron, nitrogen and phosphorous substitutionally doped single-wall carbon nanotubes studied by resonance Raman spectroscopy

Substitutional doping on single-wall an on multi-wall carbon nanotubes is possible by adding new atoms during the growing process. In this work we analyze the changes in the Raman spectra of SWNT samples substitutionaly doped with boron, nitrogen, and phosphorous. We find that small amounts of dopants are not enough to change the frequency of the tangential G mode, but there is a doping-dependent shift in omega(G) when the P-doped SWNTs are measured at high laser power, indicating that doping can change the thermal properties of SWNT bundles. This result seems to hold also for B-doped samples, but not for N-doped SWNTs, showing a different behavior for donors (P- and N- doping). The I-D/I-G ratio analysis to provide information about the doping level in the SWNT samples is also discussed. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim