Underlying principles of Ge-induced early cluster-to-layer transition for ultrathin Ag layer formation on oxides

The fabrication of continuous Ag layers with thicknesses of <10 nm are challenging. Moreover, information on the crucial factors responsible for early cluster-to-layer transition is limited. Hence, this study focuses on the effects of thin Ge interlayers in forming Ag layers on SiO_x substrates. Experimental and numerical analyses demonstrate the active migration and intermixing of atomic Ge in the Ag and SiO_x matrices during the early Ag layering stages. The incorporation of Ge into Ag matrices facilitates a faster cluster-to-layer transition than those with Al and Cu. Ge-mediated Ag clustering reduces the rearrangement momenta of extremely small Ag clusters densely concentrated on SiO_x substrates. This is attributed to the Ge-induced reduction in the diffusion of atomic Ag in the surfaces of volatile Ag clusters and consequently, the suppression of cluster coalescence. These findings provide insights into the unconventional role of Ge in Ag clustering dynamics. Thus, this study presents a crucial framework for optimizing Ag wetting on oxide substrates with ultralow optical and electrical losses via extreme dissipation of the residual amounts of metalloid wetting-inducing elements.