Growth of vertically aligned carbon nanotubes for electrical applications using water-assisted chemical vapor deposition

Abstract

Vertically aligned carbon nanotubes (VACNTs) were successfully grown by water-assisted chemical vapor deposition (WACVD) on different substrates. Using water and acetylene, we were able to produce samples of dense and aligned carbon nanotubes (CNTs), and remove the amorphous carbon generated during synthesis. The CNTs samples were grown on silicon, copper, graphite and carbon paper substrates, using different thin films as diffusion barriers between catalyst and substrate materials. Silicon was chosen because of the number of published studies regarding synthesis on this substrate and due to its widespread use in electronics and microelectronics. Nanotubes were also grown on conductor substrates such as Cu, carbon paper or graphite because of their interesting electrical applications, such as the widespread use of copper for electrodes. The CNTs obtained were highly vertically aligned, dense and ordered, as characterized by scanning electron microscopy, and of considerable length (ranging from 20 to 200 μm). VACNTs were obtained on all substrates used. The electrochemical behavior of CNTs grown on carbon paper and graphite was characterized by cyclic voltammetry, showing promising electrical properties, such as 90 mF·cm-2 area capacitance, to yield high quality devices. Raman spectroscopy was used to characterize their morphological structure and prove the existence of single-wall nanotubes.