Robustness of tungsten single atom tips to thermal treatment and air exposure

Abstract

Experiments aimed at assessing the robustness of nitrogen-etched, single-atom tips (SATs) prepared using W(111) single crystal wire were performed. Our experiments showed that single-atoms tips sustain minimal damage when exposed to atmospheric conditions and can be readily and quickly nitrogen-etched to single-atom tips thereafter. The SATs can be annealed at temperatures up to 1100°C with minimal shape changes. Moreover, annealing temperatures in excess of 1200°C resulted in an apex faceting which may prove important in further single-atom tip creation. Procedures for warming of the SATs from operating temperatures of 80K were also evaluated to determine conditions that limit tip contamination. These results show that SATS could be fabricated in a dedicated vacuum system and subsequently transferred to other instruments where they would undergo a brief conditioning procedure to recover the single-atom apex configuration prior to being subjected to operating conditions.