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Journal articles
Fast and reliable fabrication of gold tips with sub-50 nm radius of curvature for tip-enhanced Raman spectroscopy
Abstract : We have developed a new electrochemical etching procedure to fabricate gold tips with sub-50 nm
apical radius of curvature with a production yield of 80% and production time lower than 5 min.
The technique is based on a two-step self-terminating process in which a gold wire is first quickly
(<1 min) pre-etched in an hydrochloric acid (HCl)/ethanol solution at high voltage (10 VDC), and then
slowly (2–4 min) etched at lower voltages (<2.5 VDC). The first step occurs under intense bubbling
conditions and allows us to thin rapidly the wire. This reduces the time required by subsequent lowvoltage
process during which the tips are formed at the liquid/air interface. A statistical analysis of
the surface morphology has been carried out on a set of 60 tips by scanning electron microscopy. The
results show that the surface roughness and the sharpness of the final tip are critically influenced by
the intrinsic granularity of the gold wires. Moreover, there is a correlation between the tip quality
and the time elapse required to complete the low-voltage etching step. Tips featuring smooth surfaces
and radii of curvature <50 nm are produced whenever the etching times are lower than 250 s, while
etching times larger than 300 s typically yield rough, blunt tips. Such a correlation can be used as
a screening criterion to select sharp tips during production with an 80% yield. The high quality of
the gold tips produced with such method is confirmed by the electromagnetic field enhancement
measured both in tip-enhanced Raman scattering and surface-enhanced Raman scattering on the tip
apex experiments.
https://hal-utt.archives-ouvertes.fr/hal-02329308
Contributor : Daniel Gavrysiak <>
Submitted on : Wednesday, October 23, 2019 - 2:53:40 PM
Last modification on : Thursday, July 16, 2020 - 10:22:34 AM
Contributor : Daniel Gavrysiak <>
Submitted on : Wednesday, October 23, 2019 - 2:53:40 PM
Last modification on : Thursday, July 16, 2020 - 10:22:34 AM