Y F Guan et al 2007 Nanotechnology 18 335306 doi:10.1088/0957-4484/18/33/335306
Y F Guan1, A V Melechko2, A J Pedraza1, M L Simpson1,2 and P D Rack1,3
Show affiliationsWe present a non-lithographic technique that produces organized nanoscale nickel catalyst for carbon nanofiber growth on a silicon substrate. This technique involves three consecutive steps: first, the substrate is laser-irradiated to produce a periodic nanorippled structure; second, a thin film of nickel is deposited using glancing-angle ion-beam sputter deposition, followed by heat treatment, and third, a catalytic dc plasma-enhanced chemical vapor deposition (PECVD) process is conducted to produce the vertically aligned carbon nanofibers (VACNF). The nickel catalyst is distributed along the laser-induced periodic surface structure (LIPSS) and the Ni particle dimension varies as a function of the location on the LIPSS and is correlated to the nanoripple dimensions. The glancing angle, the distance between the ion beam collimators and the total deposition time all play important roles in determining the final catalyst size and subsequent carbon nanofiber properties. Due to the gradual aspect ratio change of the nanoripples across the sample, Ni catalyst nanoparticles of different dimensions were obtained. After the prescribed three minute PECVD growth, it was observed that, in order for the carbon nanofibers to survive, the nickel catalyst dimension should be larger than a critical value of ~19 nm, below which the Ni is insufficient to sustain carbon nanofiber growth.
81.16.-c Methods of nanofabrication and processing
81.15.Jj Ion and electron beam-assisted deposition; ion plating
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, etc.)
Surfaces, interfaces and thin films
Issue 33 (22 August 2007)
Received 24 May 2007, in final form 26 June 2007
Published 25 July 2007
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