Berlin 2018 – scientific programme

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DS: Fachverband Dünne Schichten

DS 11: Thin Film Properties: Structure, Morphology and Composition (XRD, TEM, XPS, SIMS, RBS, AFM, ...): Session II

DS 11.13: Talk

Tuesday, March 13, 2018, 12:45–13:00, H 0111

Fabrication and structural characterization of diamond coated tungsten tips — •Alexander Tafel¹, Mingjian Wu², Erdmann Spieker², Peter Hommelhoff¹, and Jürgen Ristein¹ — ¹Department Physik, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91058 Erlangen — ²Department Material Science, Institute of Micro- and Nanostructure Research Center for Nanoanalysis and Electron Microscopy (CENEM), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91058 Erlangen

Coating metal nanotips with a negative electron affinity material like hydrogen terminated diamond promises a high brightness photocathode. Dip seeding in detonation diamond suspensions in combination with nitrogen flow towards the tip apex and subsequent plasma enhanced chemical vapor deposition results in thin and dense diamond films along the tip from shaft to apex. The seeding density can even be controlled locally by the nitrogen flow, which counteracts forces occurring during solvent evaporation. With this technique a homogeneous coating of a complete tip with a dense and 100 nm thin diamond film as well as a selective coating of the tip apex only with 20 nm thin diamond were achieved. (HR)TEM and electron diffraction reveal that columnar nanocrystalline diamond with <110> texture and graphitic tissue between the grains was grown on the tungsten tip. An average of 17 % sp²-bonded carbon is estimated from the fine structure of the C(1s) electron energy loss spectrum.