Horizontally oriented long carbon nanotubes grown on Si substrates by using a catalytic Chemical Vapor Deposition process
E. Dervishi, Z. Li, Y. Xu, F. Watanabe, V. Saini, A.R. Biris, A.S. Biris
University of Arkansas at Little Rock, US
Keywords: long carbon nanotubes, horizontally oriented, chemical vapor deposition
Abstract:High quality long carbon nanotubes (with lengths in hundreds of micro-meters) were efficiently grown on Si films by using a Radio-Frequency (RF) catalytic chemical vapor deposition method. Small amounts of Fe catalyst solutions were deposited on oxidized Si films, and two different types of hydrocarbon sources (methane/acetylene) were separately exploited to synthesize long and aligned nanotubes. The influence of hydrocarbon type and temperature on carbon nanotube (CNT) morphology and growth rate was systematically studied by using multiple techniques including Atomic Force Microscopy (AFM),Scanning Electron Microscopy (SEM) and Raman Spectroscopy. The amount of the catalyst solution deposited onto the Si wafer was varied and its affect on the CNT morphology and diameter distribution is also discussed. It was found that horizontally and randomly aligned CNTs were grown on Si films depending on the synthesis conditions. As the amount of the catalyst solution and reaction temperature increases, long and aligned isolated nanotubes as well as dense networks are grown all over the Si surface. The Raman spectroscopy studies indicate that CNTs grown with high catalyst concentration have lower crystallinity but larger diameters when compared to the nanotubes grown from a lower amount of catalyst.