Selective area growth of carbon nanostructure synthesized by catalyst-assisted conversion of nanodiamond films

The electron field emission properties of carbon nanotubes (CNTs) formed by catalyst-assisted solid-state growth process from nanodiamond films were investigated. The SEM and Raman spectroscopy examinations show that the nanodiamond films were converted into carbon nanotubes when they were coated with a thin layer of Fe, Co or Ni films (similar to 1.0 nm) and then postannealed at high enough temperature (similar to 1000 degrees C). Precoating a catalytic metal layer is of prime importance to induce the phase transformation process. The field emission properties of nanodiamond films have been dramatically improved. The turn on field was reduced from E-Dia = 36-44 V/mu m for nanodiamond films to E-CNTs = 11 to 16 V/mu m, whereas the electron field emission capacity was increased from J(e(Dia)) = 110 mu A/cm(2) for nanodiamond films to J(e(CNTs)) = 30 mA/cm(2) after the conversion process. The electron field emission of the solid-state converted CNTs thus obtained are superior to those of the CNTs grown from CVD process due to the suppression of carbon soots formation. (c) 2004 Elsevier B.V. All rights reserved.