Effect of MgO coating on field emission of a stand-alone carbon nanotube

Field emission properties of a stand-alone MgO-coated carbon nanotube (CNT) have been investigated by a field emission microscopy. A finite element method is used to analyze the electric field distribution on the surface of a CNT and in the layer of MgO. It is found that the dielectric MgO layer decreases the strength of electric field on the CNT surface and then increases the tunnel barrier of field emission. However, it is observed that the MgO coating largely decreases the fluctuation of the emission current from a CNT especially in the current of over 10(-7) A. (C) 2007 American Vacuum Society.