Two-step controllable electrochemical etching of tungsten scanning probe microscopy tips

Yasser Khan, Hisham Al-Falih, Tien Khee Ng, Boon S. Ooi, Yaping Zhang

Research output: Contribution to journalArticlepeer-review

43 Scopus citations


Dynamic electrochemical etching technique is optimized to produce tungsten tips with controllable shape and radius of curvature of less than 10 nm. Nascent features such as dynamic electrochemical etching and reverse biasing after drop-off are utilized, and two-step dynamic electrochemical etching is introduced to produce extremely sharp tips with controllable aspect ratio. Electronic current shut-off time for conventional dc drop-off technique is reduced to ?36 ns using high speed analog electronics. Undesirable variability in tip shape, which is innate to static dc electrochemical etching, is mitigated with novel dynamic electrochemical etching. Overall, we present a facile and robust approach, whereby using a novel etchant level adjustment mechanism, 30° variability in cone angle and 1.5 mm controllability in cone length were achieved, while routinely producing ultra-sharp probes. © 2012 American Institute of Physics.
Original languageEnglish (US)
Pages (from-to)063708
JournalReview of Scientific Instruments
Issue number6
StatePublished - Jun 22 2012

ASJC Scopus subject areas

  • Instrumentation


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