Fabrication of nano ion-electron sources and nano-probes by local electron bombardment

A new method for fabricating nano ion-electron sources and nano probes with an apex in the range of 1 nm is introduced. The method is based on bombarding a regular tip apex with electrons extracted and accelerated from a nearby source by the electric field. This can be achieved by placing a metal ring around a precursor metal tip at a level below the tip apex in a field ion microscope (FIM). The metal ring is then heated, by a grounded DC power source, to a temperature below the thermionic emission value. The electric field between the tip and the hot ring is high enough to cause electrons to be extracted from the metal ring, i.e. Schottky field emission, and then accelerated to the shank with energy sufficient to dislodge atoms from the shank. An atomic scale apex with a single atom end can be obtained by monitoring the evolution of the tip apex due to the movement of mobile atoms while adjusting the tip electric field and the temperature of the metal ring. As this method depends only on the electron bombardment mechanism, this makes it a clean process that can be applied to any metal or heavily doped semiconductor materials appropriate for generating a high electric field for FIM applications.