Field emission from carbon nanotubes of various tip structuresJisoon Ihm and Seungwu Han
In an effort to understand the mechanism of the field emission from carbon nanotubes, we have performed ab initio pseudopotential electronic structure calculations for various edge geometries of the (n,n) singlewall nanotube with or without applied fields. It is found that the applied field shifts localized states at the edge to a lower energy, resulting in a large accumulation of electrons at the tube end. The amount of the charge buildup and the corresponding local field enhancement are significantly dependent on the tip geometry.
Among the systems studied, the one with the zigzag edge exposed by a slant cut is found to be the most favorable for the emission due to the existence of unpaired dangling bond states around the Fermi level. The next favorable geometry is the capped nanotube where $\pi$-bonding states localized at the cap and pointing to the tube axis direction occur at the Fermi level. A scaling rule of the induced field linear in the aspect ratio of the tube is also obtained.
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Last modification: 1999.07.15 (Thursday) 11:33:00 EDT