Patent ID: 8460049

Claim:
A method of fabricating a nano ion electron source comprising: placing an assembly of precursor tip with an apex and a shank and a heating metal ring in a field ion microscope chamber; placing the metal ring around the precursor tip along the shank at a level below the apex; applying a direct current from a current source to the metal ring to heat the ring; applying an electrical field to the precursor tip in the field ion microscope; wherein the metal ring is exposed to a high electric field from the tip, leading to generation of Schottky field emission of electrons from the metal ring, wherein the applied electrical field is sufficient to cause the electrons to be extracted and accelerated from the metal ring to strike the shank with an energy sufficient to dislodge atoms from the shank; and monitoring the evolution of the tip apex due to movement of dislodged atoms from the shank to the apex while adjusting the electrical field and adjusting the voltage and temperature of the metal ring until the apex is sharpened to form a nanotip with a desired apex atomic structure.