Self-organized patterned arrays of Au and Ag nanoparticles by thickness-dependent dewetting of template-confined films

In this work we report on the formation of self-organized and multimodal sized patterned arrays of Au and Ag nanoparticles on SiO₂ surface exploiting the thickness-dependent solid-state dewetting properties of template-confined deposited nanoscale films. In this approach, the Au and Ag surface pattern order, on the SiO₂ substrate, is established by the template confined deposition on a micrometric scale, while the solid-state dewetting phenomenon is induced by thermal processes (below the Au and Ag melting temperature). The deposited films have not an uniform thickness. They, instead, present a controlled thickness due to shadowing mask effects during depositions. Such an inhomogeneity can be further controlled by changing the deposition angle. After the dewetting process, scanning electron microscopy analyses allowed us to correlate the mean diameter 〈D〉 and spacing 〈s〉 of the formed nanoparticles by the thickness h of the deposited films. Despite the dewetting process of the Au and Ag films occurs in the solid state, relations describing the evolution of 〈D〉 and 〈s〉 with 〈h〉 typical of the linear hydrodynamic spinodal dewetting process of liquid films, 〈D〉 ∝ h ^5/3 and 〈s〉 ∝ h ², were verified within a 20 % experimental error. As a consequence we call this process “pseudo-spinodal dewetting”.