Fabrication of carbon nanoflowers by plasma-enhanced chemical vapor deposition

Two and three-dimensional (2D and 3D) carbon nanoflowers have been prepared on silicon (1 1 1) substrates by plasma-enhanced chemical vapor deposition, using CH₄, H₂ and Ar as reactive gases in the presence of Fe catalyst. The flower patterns are controlled by the flux ratio of the carrier gas, the reaction pressure and the growth temperature. Through observation by scanning electron microscopy, we find that the 2D carbon nanoflowers are formed by various nanoleaves while the 3D flowers are composed of hundreds of nanofibers. The former is related closely to the flux ratio of gas and the reaction pressure, while the latter depended mainly on the growth temperature. The nucleation and growth process of the nanoflowers seem to be a vapor/liquid/solid mechanism.