Spectroscopic ellipsometry on metal and metal-oxide multilayer hybrid plasmonic nanostructures

Abstract

The effective medium approximation is used to determine the optical constants of novel silver (Ag)/indium-tin oxide (ITO) multilayer nanopillar structures within the 300-800 nm wavelength range. The structures are modeled as inclusions in air with the pillar volume fraction at 42.4%, agreeing with SEM images of the sample. The simulated reflection intensity of the nanopillars is much less than that of the planar reference sample and is a result of the small difference between the refractive index of the top effective medium layer and that of air. Furthermore, the minimum in the reflection at around 450 nm in the nanostructured sample is evidence of surface plasmon enhancement, indicating suitability for plasmonic applications. The simulated Brewster angle decreases in the pillar region, which is an indication of smaller effective refractive index.

Nanoimprinted Hybrid Metal-Semiconductor Plasmonic Multilayers with Controlled Surface Nano Architecture for Applications in NIR Detectors

“…Fabrication of imprinted nanopillar structures of polyacrylonitrile (PAN) with the desired pitch/aspect ratio and their characterization has been previously reported [6,36,37,38]. 1 cm × 1 cm ITO nanopillar electrodes were fabricated by depositing ITO on the previously nanoimprinted PAN structures, using an electron beam deposition technique.…”

“…The free carrier concentration of TCOs can be tuned under suitable doping and fabrication conditions by depositing a very thin layer of a noble metal (here Ag), with the effective metal carrier concentration variable through nanostructuring. The Maxwell-Garnett effective medium approximation was used to find the ratio of Ag and ITO in the core shell structures [37]. The bulk plasma frequency of Ag is 9.1 eV [54], however, depolarization charges due to the dielectric core cause a screened plasma frequency which is smaller than the bulk plasma frequency [55].…”

“…The dielectric constants of the top ITO layer were calculated using the Bruggemann mixing law [37]. Here we assume that the ITO pillars are in the form of inclusions inside air.…”

Light harvesting in organic solar cells using a nanostructured ITO grating

“…This is particularly useful for the nanostructured hybrid (Ag \ ITO) plasmonic electrodes we have reported earlier. Details of the ellipsometry study on these plasmonic electrodes with ITO shells has can be found in [15].…”

Characterization of Nanorod Structure Using Spectroscopic Ellipsometry

“…The ellipsometer offers the added advantage of obtaining phase information, thereby making it a powerful optical characterization technique [15] [16]. Different nanostructures such as split ring resonators [7], fishnet metamaterial [17] [18] etc. have been characterized using the method of ellipsometry.…”