Cold and Laser Stimulated Electron Emission from Nanocarbons

Various types of electron emission are being nowadays applied for the creation of electron beam sources in the vacuum electronic devices such as X-ray, and cathode-ray tubes, microwave devices etc. Study of the electron emission is also an important tool for determination of basic characteristics and specific features of different materials. Carbon based materials have been the focus of many studies of their electron emission properties from fundamental and applied points of view. This is particularly owing to strong atomic bonding in graphite and diamond which provides chemical inertness and sustainability of carbon cathodes under the action of residual gas ion bombardment. Recently great emphasis has been attracted to nanostructured forms of carbons. The field (or cold) emission characteristics of carbon nanotubes are commonly attributed to geometric effects, and other more complex effects associated with field penetration, electronic structure and stationary states. Nanocrystalline diamond films have displayed similar field emission characteristics at relatively low applied fields, and this effect has been assigned to the graphitic carbon inclusions. The efficient field enhancement from these nanodiamond films has been attributed to both morphological effects and grain boundary electrical conductivity. In this paper we review basic theoretical approaches, our computer simulations and recent experimental studies of the electron emission from nanocarbon materials.