Theoretical description of intensive electron emission from ultra-sharp nanotips

Summary form only given, as follows. In the presented work, electron field emission from a single atom on the apex of an atomically sharp tip is described in terms of a model of electron tunneling from a state, localized in the spherical potential well. In such a formulation, the considered problem is partially similar to the ´classical´ approach to alpha decay treatment. Nevertheless, it should be noted that, traditionally, in the alpha decay case: 1) the WKB expression for the probability of particle tunneling is used; and 2) the image forces potential is not taken into account. We solve the Schrodinger equation numerically. A numerical treatment allowed us to avoid difficulties, connected with the WKB approach validity for extremely high field strengths, when the tunneling probability can be close to unity. It is shown, in particular, that the image forces potential, of course, must be taken into account but the distinction in the expression for this potential has practically no influence upon Fowler-Nordheim plots. Electron energy distributions were calculated for different barrier shapes. The limit brightness abilities of point electron sources were analyzed in dependence of the apex of the nanoemitter curvature radius and applied electric field. The problems of electron source coherence were also considered.