Gold nanoparticle arrays using pre-patterned silicon substrates

This work demonstrates a method for producing well-ordered gold nanoparticle arrays using a pre-patterned silicon substrate. The study starts with an investigation of particle formation on flat silicon substrates. Surface coverage is presented as a function of different annealing temperatures (from unannealed to 1100 °C), and particle size distributions are characterized at 1100 °C to study first the annealing process. Silicon substrates pre-patterned with square features were also coated with gold layers ranging in thickness from 10 nm to 40 nm. The dewetting process was then induced by annealing in a furnace at 800 °C and 1100 °C. These varying temperatures and layer thicknesses revealed that a 20 nm initial gold layer deposited onto a square lattice and annealed at 1100 °C resulted in a well-defined nanoparticle array, in contrast to results obtained on flat substrates. Crystallite sizes, determined by X-ray diffraction were smaller than or equal to the smallest determined particle size. Optical absorbance spectroscopy measurements revealed shifts in spectra associated with the plasmonic properties of the nanoparticles.