  Early results on the plasma deposition of dielectric thin films on acoustic
wave (AW) activated substrates revealed a densification pattern arisen from the
focusing of plasma ions and their impact on specific areas of the piezoelectric
substrate. Herein, we extend this methodology to tailor the plasma deposition
of metals onto AW-activated LiNbO3 piezoelectric substrates. Our investigation
reveals the tracking of the initial stages of nanoparticle (NP) formation and
growth during the submonolayer deposition of silver. We elucidate the specific
role of AW activation in reducing particle size, enhancing particle
circularity, and retarding NP agglomeration and account for the physical
phenomena making these processes differ from those occurring on non-activated
substrates. We provide a comparative analysis of the results obtained under two
representative plasma conditions: diode DC sputtering and magnetron sputtering.
In the latter case, the AW activation gives rise to a 2D pattern of domains
with different amounts of silver and a distinct size and circularity for the
silver NPs. This difference was attributed to the specific characteristics of
the plasma sheath formed onto the substrate in each case. The possibilities of
tuning the plasmon resonance absorption of silver NPs by AW activation of the
sputtering deposition process are discussed.
