Multilayered metal catalysts for controlling the density of single-walled carbon nanotube growth

Ion beam sputtering has been used for the sequential deposition of metal mu ltilayers on various substrates to control the density of single-walled car bon nanotubes (SWNTs) synthesized by chemical vapor deposition. Underlayers (10-20 nm) of Al and Ir were found to activate the substrates for SWNT gro wth with Fe as active catalyst. Adding Mo as cocatalyst gives increased pro duction of SWNTs and the density can be controlled by varying the thickness of the different metal layers. High-resolution transmission electron micro scopy and Raman scattering are used to characterize the SWNTs. (C) 2001 Els evier Science B.V. All rights reserved.