Defect induced lowering of work function in graphite-like materials

Different carbon materials have shown unusually high efficiency of electron field emission. The device application of the carbon cold cathodes requires a fundamental understanding of the emission mechanism. We describe the emission properties of carbon thin films grown by chemical vapor deposition. The structure, phase composition and electronic properties peculiar to the film material were investigated. New model of electron emission sites and mechanism of field electron emission are proposed. In accordance with the proposed model the electron emission in carbon materials occurs from sp(3)-like defects in an Sp(2) network of graphite-like material. The corresponding mechanism of field emission consists of electrons escaping into vacuum by tunneling from the Fermi level of the graphite material through the atomically thin sp(3)-like layer and the energy barrier on its surface. (C) 2002 Elsevier Science B.V. All rights reserved.