An abnormal thermal field emission high brightness and stability point electron source

Abstract

Experimental and theoretical researches of thermal field emission properties ZrO2/W nanoheterostructures (NBS), formed by thin (~10 nm) ZrO2 layers on the W microcrystals surface oriented in the <;100> and <;111> directions, are carried out. A study of the thermal field electron emission from a thin dielectric (ZrO2) layers at the needle - shaped W and Mo microcrystals have shown that the emission process behavior does not agree with the classical thermal field emission theory. It is established that at temperature of NBS substance ~ 2000 ±100 K electron emission process is activated at rather low values of extraction fields intensity (less ~ 50 V/μm). It is shown, that in a stationary mode of an electron emission from the investigated NBS surfaces the emission current density achieves abnormal high values (the order ~ 108 A/cm2) and the reduced brightness of an emitted electrons flux can make ~ 106A/(cm2sr V). The detected phenomenon of sharp increase of emission ability for investigated NBS was named abnormal thermal field emission (ATFE). The model of the found out phenomenon for field emission process from a NBS of a kind: a conductor (metal) - a thin dielectric layer, is offered.