Pulsed laser induced dewetting of Au thin films on Ta2O5 substrates

Abstract

Au nanoparticle arrays are formed by pulsed laser-induced dewetting from chemically polished and anodically formed templated (dimpled) Ta. Here we demonstrate clear evidence that pulsed laser-induced dewetting (PLiD) of thin films of Au on Ta 2 O 5 /Ta follows the spinodal dewetting mechanism, which was further found to be dependent on the surface topology of the substrate. We examine two different Ta 2 O 5 -coated Ta substrates (dimpled Ta and chemically polished Ta), and find that for Au nanoparticles (NPs) formed on polished Ta, the diameter, spacing and NP number density were related to the initial Au film thickness ( h ) by h 5/3 , h 2 and h −4 , respectively. The diameter, spacing and number density of NPs formed on chemically polished Ta were found to not vary with either laser fluence (260–300 mJ·cm −2 ) or irradiation time (0.1–60 s). On dimpled/patterned Ta substrates, thicker (>4 nm) Au films resulted in Au NPs that exhibit a more uniform diameter and spacing that mirrors the dimpled Ta template, and the dewetting is thought to proceed by an alternative mechanism.