Reproducible Electrochemical Etching of Tungsten Probe Tips

Abstract

An electrochemical procedure in KOH electrolyte has been developed to reproducibly produce ∼5 nm radius tungsten probe tips. It has been found that a spurious electrochemical etching process, driven by the natural potential difference between an Ir electrode and the W tip, causes rapid tip blunting at the end of the electrochemical etching period. By electrically reversing this potential difference within 500 ns following tip separation, the blunting process is eliminated yielding sharp tips with varying cone angles.

Electrochemically etched sharp aluminium probes with nanoporous aluminium oxide coatings: demonstration of addressed DNA delivery

“…4,5 This process can achieve a tip apex radius of 5 nm. 6 Tungsten, platinum-iridium, gold, and silver are the most commonly used materials for nanoprobe fabrication. 7 A sharp tip with a nanoporous structure has a signi-cantly increased surface area.…”

Surface micromachining via solid electrochemical reaction on oxide ion conductors

“…It seems that hard materials such as carbon based ceramics (glassy carbon and SiC) or hard metals (W, Mo) are appropriate targets for the proposed technique, because these non-oxide materials form gaseous or volatile oxidation products. Typically, the microstructures of these materials can be used as microelectrodes or micro-parts for high temperature use [6,16]. etching in solutions have been frequently applied by many groups [16,17].…”

Dynamic electrochemical-etching technique for tungsten tips suitable for multi-tip scanning tunneling microscopes

“…Especially, electrochemical etching of a tungsten wire is widely used for STM tips [54][55][56][57][58][59][60][61][62][63][64][65][66]. Thanks to contributions from many researchers, sharp tungsten tips having around 20-nm diameter at the apex can now be acquired routinely [64][65][66].…”