Atom Probe Analysis of Tungsten Tips Fabricated by 6Field-assisted Oxygen Etching

It is important to realize electron and ion emitters with small source sizes for high -spatial -resolution microscopy applications. Field -assisted oxygen etching is one of the methods used to form an ultra -sharp tip or nano -protrusion on a large tip; however, the emitting surface that emits electrons and ions is also oxidized. The composition of the tungsten tips fabricated using the two field -assisted etching methods was analyzed using a pulsedvoltage atom probe. The tip, sharpened using the decreasing bias method during etching, consisted of only tungsten atoms. In the other method, a large base tip with a nano -protrusion, fabricated by applying the fixed bias method during etching, was covered with tungsten oxide, even though the nano -protrusion comprised only tungsten atoms. These differences in composition are attributed to changes in the field strength and region of oxidation during the etching process, which agrees with previously