Fabrication and characterization of suspended single-walled carbon nanotubes

Suspended single-walled carbon nanotubes (SWCNTs) between SiO2 pillars via a direct lithographic route using a simple mixture of catalyst precursor [Co(III) acetylacetonate, Co(acac)3] and conventional electron beam resist (ma-N2403) were fabricated. The catalytic electron beam resist (Cat-ER) layer plays dual roles as a catalyst and a resist layer for the growth and alignment of CNTs, respectively. The structure of the grown nanotube was characterized by Raman spectroscopy (633 nm laser excitation). Nanotubes grown from Cat-ER with Co(acac)3 show the typical Raman spectra of SWCNTs which are characterized by the strong tangential bands near to 1590 cm−1 and radial breathing modes (RBMs) in the low frequency region (<300 cm−1). The calculated diameter of the probed nanotubes individually corresponds to the range 0.86–1.77 nm.