Growth of separated individual SWCNTs from metal:matrix templates

Metal: matrix templates deposited by physical vapor deposition (PVD) were used to grow separated, individual single-walled carbon nanotubes (SWCNTs). The templates are thin films of 2 nm thickness, where the metal is either segregated as nanoparticles (NPs) or diluted in the matrix. The upper limit of the NP diameter was confined by the film thickness. The function of the matrix is to prevent the metal particle from coalescence during nanotube growth by chemical vapor deposition. SEM, TEM, AFM, and Raman mapping were used for template and carbon nanotube characterization. SWCNTs with a narrow, monomodal diameter distribution are obtained from templates with NPs of 2 nm diameter. About 50 % of the SWCNTs detected by Raman mapping have a diameter between 1.3 nm and 1.5 nm. Smaller SWCNT diameters down to 0.8 nm are obtained from templates where the metal is diluted in the matrix. For these templates a bimodal SWCNT diameter distribution was observed. The two maxima of the CNT diameter distribution were found at about 0.8 nm to 1.0 nm and at about 1.2 nm to 1.4 nm, respectively. The CNTs are in their majority separated each from other.