Electrochemical etching and field-directed sputter sharpening production of atomically sharp tungsten tips for scanning tunneling microscopy

Abstract

One of the great challenges of scanning tunneling microscopy is the production of atomically sharp tips. In this research, we have produced STM tips by electrochemical etching and subsequent field-directed sputter sharpening. Tips produced using these techniques were characterized using transmission electron microscopy. Here, we show that we have successfully produced atomically sharp tungsten tips with an apex radius of up to 1.4 nm. Although we have been able to reproduce field-directed sputter sharpening of tungsten tips, it remains unclear under which circumstances this method yields the best results. We suggest further systematical research in order to optimize this promising STM tip production technique.