First-principles study of field-emission from carbon nanotubes in the presence of methane

Carbon nanotubes are promising candidates for field-emitters. It has been shown that the presence of various gases can enhance or degrade the performance of nanotube emitters. Small hydrocarbons are of particular interest because of their ability to enhance the emission properties. The authors report a simulation study of field-emission from a carbon nanotube exposed to methane in various configurations with an emphasis on calculating the emission current. The Hartree-Fock theory combined with a Green's functions approach was used for the simulations. It was observed that the change in the emission current strongly depends on the particular arrangement of the methane molecules on the nanotube. (C) 2012 American Vacuum Society. [DOI: 10.1116/1.3684980]