Field Assisted Reactive Gas Etching of Multiple Tips Observed using FIM

Abstract A simple and cost effective method to fabricate multiple tungsten (W) single atom tips (SATs) from both poly and single crystalline wires is reported. Two or four tips attached to a holder are electrochemically etched together in NaOH solution followed by a controlled field assisted reactive gas etching in vacuum using nitrogen as an etching gas and helium as an imaging gas. A Common high voltage is applied simultaneously to all nanotips to shape the apexes towards single atoms. Single atom tips were achieved for both W(111) and W(110) while trimer tips were also achieved for W(111). This observation can lead to an important step towards realizing simplified etching processes of multiple tips which in turn can help to simultaneously fabricate numerous tips leading to mass fabrication and characterization.