Field induced electron emission from a nanoheterostructured surfaces of the W and Mo needle-shaped microcrystals

A study of the field emission properties of ZrO₂/W and ZrO₂/Mo nanoheterostructures is presented. The nanoheterostructure (NHS) was represented by a thin (~3-10 nm) ZrO₂ layer at the tip of a needle-shaped W<;100>, W<;111>, Mo<;100> and Mo<;111> microcrystals (MC). It is established, that at temperature (T_s) of NHS substance T_s~ (1900±100) K process of thermal field electron emission is activated at rather low values of intensity (F) extraction fields (less ~ 10-50 V/μm). It is shown, that in a stationary mode of a thermal field electron emission from the investigated NHS surfaces the density of an emission current achieves abnormal high values (the order ~10⁸ A/cm²) and a normalized brightness of an emitted electrons flux can make ~ 10⁶ A/(cm² sr V). The revealed phenomenon of a sharp rise in emissive ability of the ZrO₂/W and ZrO₂/Mo NHSs in the certain range of ZrO₂ layer thicknesses and nanoheterostructured substance temperatures T_s was named "abnormal thermal field emission" (ATFE).