Field Emission and Radial Distribution Function Studies of Fractal-like Amorphous Carbon Nanotips
1 Department of Physics, Institute for Functional Nanomaterials, University of Puerto Rico, Rio Piedras, P.O. Box 23343, San Juan, PR, 00931, USA
2 Polymeric Materials Branch, Materials and Structures Division, National Aeronautics and Space Administration Glenn Research Center, 21000 Brookpark Road, Cleveland, OH, 44135, USA
Nanoscale Research Letters 2009, 4:431-436 doi:10.1007/s11671-009-9270-5Published: 13 February 2009
The short-range order of individual fractal-like amorphous carbon nanotips was investigated by means of energy-filtered electron diffraction in a transmission electron microscope (TEM). The nanostructures were grown in porous silicon substrates in situ within the TEM by the electron beam-induced deposition method. The structure factorS(k) and the reduced radial distribution functionG(r) were calculated. From these calculations a bond angle of 124° was obtained which suggests a distorted graphitic structure. Field emission was obtained from individual nanostructures using two micromanipulators with sub-nanometer positioning resolution. A theoretical three-stage model that accounts for the geometry of the nanostructures provides a value for the field enhancement factor close to the one obtained experimentally from the Fowler-Nordheim law.