Strong Electron - Plasmon Interaction in Scanning Electron Microscopy

Moshik Cohen Faculty of Engineering, Bar-Ilan University, Ramat-Gan, Israel Bar-Ilan Institute for Nanotechnology & Advanced Materials, BINA, Ramat-Gan, Israel Yossi Abulafia Bar-Ilan Institute for Nanotechnology & Advanced Materials, BINA, Ramat-Gan, Israel Zeev Zalevsky Faculty of Engineering, Bar-Ilan University, Ramat-Gan, Israel Bar-Ilan Institute for Nanotechnology & Advanced Materials, BINA, Ramat-Gan, Israel

Nanoplasmonics has fashioned rapid expansion of interest from both fundamental and applicative perspectives, with potential for becoming a true life – changing technology1–3. However, fundamental and practical limitations impede plasmonic technology from fulfilling its potential. This includes nanofabrication inaccuracies, difficulties in delivering light to nanoscale devices and nanocharacterization complexities.

Here, for the first time, we address these limitations by performing simultaneous excitation, nanoimaging and functional characterization of plasmonic devices using scanning electron microscopy (SEM). We use a high-energy (50KeV), focus(1nm) electron beam to excite optical plasmonic modes in nanometallic devices.

Figure 1| Illustration of plasmonic excitation and nanoimaging with SEM. Dipole nanoantenna is connected to MIM waveguide. The device is illuminated by a high energy scanning electron beam, which excites optical plasmons in the device.


We analyze the emitted electrons to obtain the broadband optical response and the geometrical topography of the devices. Our approach achieves optical characterization and topography imaging, both with deep subwavelength spatial resolution of only 30nm. High resolution images that include both topography and functional information are created within less than 10 seconds. Our experimental results are in good agreement with full wave numerical calculations, and supported by an analytic model for increased physical insight.

Our findings enable rapid prototyping of nanoplasmonic devices operating at optical frequencies. It will now be possible to accurately deliver high energy to nanoscale geometries, and precisely analyze their response via electron - plasmon interaction.

References

  1. Cohen, M., Shavit, R. & Zalevsky, Z. Observing Optical Plasmons on a Single Nanometer Scale. Sci. Rep. 4.(2014).
  2. Cohen, M., Zalevsky, Z. & Shavit, R. Towards integrated nanoplasmonic logic circuitry. Nanoscale 5, 5442–5449 (2013).
  3. Brongersma, M. L. & Shalaev, V. M. The Case for Plasmonics. Science 328,
    440–441.(2010).

moshik.cohen80@gmail.com









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