Optimum Thickness of Al2O3 Support Layer for Growth of Singlewalled Carbon Nanotubes

Abstract

An optimum thickness of Al2O3 support layer (ASL) for growth of singlewalled carbon nanotubes (SWCNTs) was systematically established. Atomic force microscopy and scanning electron microscopy results clearly revealed that increasing ASL thickness (t(ASL)) resulted in increased ASL grain diameter and root mean square roughness. This significantly affected the diameters of CNTs through the restricted formation of Fe nanoparticles. As a result, SWCNTs and multiwalled CNTs were simultaneously synthesized using ASLs with t(ASL) = 5, 50, and 100 nm, which were confirmed using Raman spectroscopy and transmission electron microscopy. In contrast, ASLs with t(ASL) 10{30 nm, were suitable for predominant growth of SWCNTs, and ASL with t(ASL) = 15nm was especially effective for growing high-quality SWCNTs with a small diameter and narrow distribution, 1.1 +/- 0.15 nm. (C) 2011 The Japan Society of Applied Physics