Microstructure and electron field emission study of diamond nanorod decorated a-SiO₂ nanowires by microwave Ar-CH₄/H₂ plasma chemical vapor deposition with addition of N₂

In our recent paper [M. K. Singh et al., Chem. Mater. 20 (2008) 1725], we reported the fabrication of Nanocrystalline diamond (NCD) fibers by template (a-SiO₂ nanowires) technique. Our present work demonstrate that the addition of nitrogen of 20% by volume in the reaction gas during synthesis induce the formation of feather-like morphology of NCD on a-SiO₂ nanowires. The feather-like morphology consists oriented diamond nanorods surrounded by an sp²-bonded carbon sheath. These have been characterized by Scanning Electron Microscopy, Transmission Electron Microscopy (high-resolution mode) and Micro-Raman spectroscopy. Electron field emission (EFE) of as-synthesized NCD fibers (with 20% N₂ addition) was observed with a threshold field of 3.5 V/μm which is quite less in comparison to previous grown NCD fibers and the current density at 10 V/μm increases around 20 times with 20% nitrogen doping in the gas source during synthesis. This may be because each diamond nanorod is enveloped in a sheath of sp²-bonded nanocarbons which provides a conducting path for electron emission.