Anomalies of the field 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 of NHS substance ~ (1900plusmn100)K process of thermal field electron emission is activated at rather low values of intensity extraction fields (less ~30-50 V/mum). 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 was named "abnormal thermal field emission" (ATFE).