AVS 58th Annual International Symposium and Exhibition
    Thin Film Division Friday Sessions
       Session TF-FrM

Paper TF-FrM10
Kinetics of Sputtered Metal Film Growth on Vertically Aligned Carbon Nanotube Arrays

Friday, November 4, 2011, 11:20 am, Room 110

Session: Thin Films: Growth and Characterization II
Presenter: Amber Reed, Air Force Research Laboratory
Authors: C. Muratore, Air Force Research Laboratory
A. Reed, Air Force Research Laboratory
A. Waite, Air Force Research Laboratory
J. Bultman, Air Force Research Laboratory
J. Hu, Air Force Research Laboratory
T. Smith, Air Force Research Laboratory
A.A. Voevodin, Air Force Research Laboratory
Correspondent: Click to Email
Controlling the surface morphology of metallized arrays of vertically aligned nanotubes (VACNTs) is useful for diverse technological applications, such as interface materials for thermal management of high-heat flux electronics and electrical contacts for MEMS switches. We have observed variation of the morphology of metal films sputtered on carbon nanotubes, ranging from thin continuous films surrounding individual bundles of carbon nanotubes along their entire length for tubes up to 100 microns in length, to metal canopies covering the surface, with only minimal penetration (10-20 microns) into the nanotube forest. There is a strong link between flux of metal ions and their kinetic energy and the morphology of metal films of technological interest, including titanium, nickel, copper, gold and aluminum. To explore the mechanisms dictating metal film architectures on VACNT arrays, we systematically altered the flux and energy of incident metal and inert gas ions. These processing conditions were characterized using a mass spectrometer and energy analyzer adjacent to VACNT substrates. For conditions of interest, film growth was carried out for different times in an ultra high vacuum processing chamber, followed by electron microscopy of VACNT film cross sections, which were examined to observe different stages of growth and identify mechanisms of film nucleation and growth on nanotube sidewalls and tips. Comparison of growth kinetics of metal films on planar (002) graphite surfaces to that observe on VACNTs was used to identify effects of curvature on film growth. Switch performance was shown to be strongly dependent on morphology.