Lithography-free synthesis of periodic, vertically-aligned, multi-walled carbon nanotube arrays

Until now, the growth of periodic vertically aligned multi-walled carbon nanotube (VA-MWCNT) arrays was dependent on at least one lithography step during fabrication. Here, we demonstrate a lithography-free fabrication method to grow hexagonal arrays of self-standing VA-MWCNTs with tunable pitch and MWCNT size. The MWCNTs are synthesized by plasma enhanced chemical vapor deposition (PECVD) from Ni catalyst particles. Template guided dewetting of a thin Ni film on a hexagonally close-packed silica particle monolayer provides periodically distributed Ni catalyst particles as seeds for the growth of the periodic MWCNT arrays. The diameter of the silica particles directly controls the pitch of the periodic VA-MWCNT arrays from 600 nm to as small as 160 nm. The diameter and length of the individual MWCNTs can also be readily adjusted and are a function of the Ni particle size and PECVD time. This unique method of lithography-free growth of periodic VA-MWCNT arrays can be utilized for the fabrication of large-scale biomimetic materials.