  The behavior of plasmonic antennas is influenced by a variety of factors,
including their size, shape, and material. Even minor changes in the deposition
parameters during the thin film preparation process may have a significant
impact on the dielectric function of the film, and thus on the plasmonic
properties of the resulting antenna. In this work, we deposited gold thin films
with thicknesses of 20 nm, 30 nm, and 40 nm at various deposition rates using
an ion-beam-assisted deposition. We evaluate their morphology and
crystallography by atomic force microscopy, X ray diffraction, and transmission
electron microscopy. Next, we examined the ease of fabricating plasmonic
antennas using focused-ion-beam lithography. Finally, we evaluate their
plasmonic properties by electron energy loss spectroscopy measurements of
individual antennas. Our results show that the optimal gold thin film for
plasmonic antenna fabrication of a thickness of 20 and 30 nm should be
deposited at the deposition rate of around 0.1 nm/s. The thicker 40 nm film
should be deposited at a higher deposition rate like 0.3 nm/s.
