FIELD-EMISSION ENERGY-DISTRIBUTION OF ELECTRONS FROM A THIN METAL-FILM

The equation describing the field emission energy distribution (FEED) of electrons escaping from an ultrathin metal film (UMF) is derived. The studied UMF has a thickness from several to tens nm. The quantum size effect (QSE) is observed in such a film, and only that part of the total electron energy E is quantized, which is associated with the motion perpendicular to the film surface. This part is called "normal" energy W. The tunneling probability through the potential barrier in the field emission depends only on W. However the electrons having the same value W have a total energy enclosed in the range <W, E(F)> (E(F) is the Fermi energy). This feature differentiates the field emission of electrons from the solid metal, and the emission occurring from the UMF. The calculated electron energy distribution curve characteristic of UMF has "steps", which correspond with the quantized "normal" energies. The envelope of this curve is the distribution curve for the bulk solid.