Effect of emitter surface structure on field-ionization and electron-emission processes

Abstract

Processes of field electron emission, field ionization and field evaporation of atoms from the emitter surface in intensive electric fields (107_lOs V/cm) are determined, in particular, by the crystallographic structure of the emitting surface. For pure metals, wherein the nonuniformity of density distribution of field emission current is due to various values of factor 3/2/E, this was first shown by E.Muller' . In the case of emission from the surface of metallic alloys the effect of the crystallographic structure on the distribution electron and field ion emission current density becomes more complicated. Such additional factors as the nature of interatomic forces responsible for structural trinsformations, different phase composition of various areas of the surface, the degree of long-range order in relevant sublattices, etc. begin to play a substantial role in emission processes. The purpose of this investigation is to elucidate the effect of alloy atomic surface structure crystallography on the processes offield electron emission and field ionization in intensive electric fields (107_108 V/cm). Such experimental conditions exist in the field emission microscope, where the distribution of electron and field ion emission current density is influenced directly by the structure of an atom-clean surface.