Surfactant Growth and Optical Studies of Plasmonic Silver Nano-Disks

Abstract

Infrared spectroscopy is used as an optical probe to spectrally characterize and tailor the lateral growth of silver nanostructures on silicon reconstructed surfaces. The silver nanostructures are prepared in ultra high vacuum environment by depositing silver onto a surfactant pre-covered silicon substrate, followed by an annealing step. Transmittance spectrum in mid-infrared region of the as-deposited film shows a tail arising from the Mie resonance of individual nano-particles whose resonant features located in visible region. After annealing, the aggregation of particles forms an atomically flat ensemble of nano-disks resulting in a significant shift of plasmonic resonance to mid-infrared. Surprisingly, this resonance position can be tuned over the entire mid-infrared region by varying the diameter of the disks. The finite different time domain simulation is performed to give a better insight into the behavior of this resonant class and proofs the existence for the dipolar resonance thereby confirms the antenna resonance of the nano-disks. [DOI: 10.1380/ejssnt.2012.239]