Effects of fabrication method of Al2O3 buffer layer on Rh-catalyzed growth of single-walled carbon nanotubes by alcohol-gas-source chemical vapor deposition

Amorphous Al2O3 buffer layers have been widely used to enhance the yield in the growth of single-walled carbon nanotubes (SWCNTs). In this study, we carried out SWCNT growth using a Rh catalyst on Al2O3 buffer layers that were prepared by three different methods based on electron beam (EB) evaporation: native oxidation of Al layer deposited by EB; thermal oxidation of Al layer deposited by EB; EB deposition of Al2O3 layer. We investigated the effects of fabrication method of the Al2O3 buffer layer on SWCNT yield and found that the SWCNT yield was the largest for Al2O3 layer prepared by EB deposition of Al2O3, while SWCNTs were not grown on the Al2O3 layer obtained by native oxidation of the Al layer. Based on the results of X-ray photoelectron spectroscopy, X-ray absorption near-edge structure, and atomic force microscopy, we examined the effects of crystalline quality and oxidation degree of Al2O3 layers on the catalytic activity.