Adjustable metal particle grid formed through upward directed solid-state dewetting using silicon nanowires

Abstract

Sub-micron sized metal particles were formed through the annealing of sputtered metal thin films on silicon nanowires (SiNWs). During high-temperature annealing, the cylindrical SiNW structures induce the solid-state dewetting behavior to consistently move up the SiNW sides and form partial-spherical particles with uniform sizes on the nanowire tops. By adjusting the size parameters of the SiNW substrate and the metal thin film, the particles can be adjusted in size and layout along an array. This contrasts with the random dewetted particles seen on planar surfaces, and known movement towards pitted nanostructures. Ag, Au, Cu, and Ni have shown equivalent particle formation behavior and some alloying is also shown to be possible. These results open a path for a well-controlled and consistent method of metal particle formation at the nano to micro-scale and offer some insight on metal particle dewetting mechanisms. Suggested applications for the resulting regular particle grids include plasmonic sensors such as SERS.