Growth kinetics and size-dependent wetting of Ag/α-Al₂O₃(0001) nanoparticles studied via the plasmonic response

Abstract

The growth of vapour-deposited silver nanoparticles on α-Al₂O₃ was studied in situ from 190 to 675 K by surface differential reflectivity spectroscopy in the UV-visible range. Changes in size, shape and density were derived from the plasmonic response modelled in the framework of interface susceptibilities by assuming that supported clusters were in the form of truncated spheres. The sticking coefficient of silver on alumina is close to one up to T ≃ 575 K before entering a regime of incomplete condensation. The Arrhenius dependence of the saturation density indicates a nucleation on defects at low temperature (T ≤ 300 K) and detrapping above. The particle size D evolution follows temporal power laws, independent of temperature and flux, which characterize the growth (D ∼ t(0.31)) and coalescence (D ∼ t(0.55)) of the film. These are indicative of the growth of isolated particles at constant density and dynamic coalescence, respectively. The wetting angle of the silver clusters is shown to increase during the growth regime, which is assigned to a combination of surface stress and mismatch-induced strain, and to decrease upon coalescence, which is attributed to plastic relaxation. For particles larger than 10 nm in size, the values of contact angle and adhesion energy level off with asymptotic limits (θ(c) = 127.5° ± 1° and 0.48 ± 0.02 J m⁻²) that nicely agree with tabulated data. This work highlights the ability of nanoplasmics to monitor in situ the growth kinetics of thin supported films.

Tuning Adhesion at Metal/Oxide Interfaces by Surface Hydroxylation

“…A continuous thin film model was also used to estimate film thickness through ratio of zinc and alumina photoemission peak area after correction of ionization cross section and spectrometer transmission function using tabulated mean free paths in bulk alumina and zinc (see SI Section S2.4). The growth of Zn films was analyzed in situ by SDRS which allows to estimate wetting angle (and adhesion energy) by fitting SDRS spectra with suitable dielectric models 22,[26][27][28][29][30][31] (SI, Section S2.1). Once the deposition was completed, the desorption energy of the film E des was determined by TPD thanks to a differentially pumped mass spectrometer.…”

Ultra Uniform Pb0.865La0.09(Zr0.65Ti0.35)O3 Thin Films with Tunable Optical Properties Fabricated via Pulsed Laser Deposition

“…On the one hand, the PLZT adatoms obtained a comparatively high kinetic energy by the high deposition temperature and excitation laser energy, which potentially increased the nucleation sites for the crystallization [31,32]. On the other hand, the reduced deposition interval allowed a favorable surface diffusion of the adatoms, which can further improve the surface uniformity [33]. Moreover, the thickness of each sample was similar due to the fixed deposition time, which was about 100 nm, as shown in Figure S4 (Supplementary Materials).…”

Formation of plasmonic nanoparticle arrays –rules and recipes for an ordered growth

“…As a consequence the nucleation density is no longer comparable to flat substrates, but significantly higher. Due to limitations in our experimental setup, the investigated temperature range is quite small, however if we compare our results to Ag NPs grown on flat Al 2 O 3 a change in number density of one order would be expected for the change from room temperature to 570 K for a diffusion limited nucleation ().…”