STEM observation of tungsten tips sharpened by field-assisted oxygen etching

Jo Onoda, Seigi Mizuno, Hiroki Ago

    Research output: Contribution to journalArticlepeer-review

    15 Citations (Scopus)


    Tungsten tips oriented toward the <111> direction were fabricated by field-assisted O2 etching, and observed by means of scanning transmission electron microscopy (STEM) and field ion microscopy (FIM). The radii of curvature of the tip apexes were sharpened from 16-20 nm to less than 2 nm. The O2 etching is considered to start from the O2 imaging region depending on the field distribution around the tip apex and shank. We estimated the effect of field distribution derived from a shank shape and applied bias voltage. The results showed that the tip with a cylindrical shank before the O2 etching became sharper than tips having an initial paraboloidal shape, with respective cone angles (defined in Fig. 3) of 58° and 80°. The field emission (FE) patterns of these etched tips became a single spot derived from the W(111) plane, and their opening angles (defined by the full width at half maximum) were 14.4° and 7.8°, respectively.

    Original languageEnglish
    Pages (from-to)1094-1099
    Number of pages6
    JournalSurface Science
    Issue number13-14
    Publication statusPublished - Jul 15 2010

    All Science Journal Classification (ASJC) codes

    • Condensed Matter Physics
    • Surfaces and Interfaces
    • Surfaces, Coatings and Films
    • Materials Chemistry


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