Theoretical analysis of field emission from atomically sharp aluminum tips

We have analyzed field electron emission from atomically sharp tips on Al(1 0 0) surfaces by using density functional calculations including effects of electric fields and currents. We have obtained a pronounced secondary peak in total energy distribution of emitted electrons in the case of a 30-atom protrusion terminated by a single atom. We have also clarified that the appearance of the secondary peak requires sufficient local barrier reduction in front of the apex atom of protrusions, which is caused by strong electric field and sharp geometry. Further, we have shown that analyses of local density of states are not necessarily sufficient to understand the features of field emission.