Structure and Optical Property Prediction of Plasmonic Metasurfaces Fabricated by Shadow Sphere Lithography

Shadow sphere lithography (SSL) is a powerful nanofabrication method to produce various two-dimensional metasurfaces and three-dimensional metamaterials. However, one of the biggest challenges for SSL is that the physical properties of the fabricated nanostructures are very hard to accurately predict even the shapes of the structures can be modeled by the geometric shadowing effect. A Monte-Carlo (MC) simulation is developed to show that a dynamic shadowing effect due to the accumulation of materials on nanosphere monolayer template as well as the detailed thin film growth mechanism play key roles in determining the structural details. For one-to-three step based SSL fabrication, the nanostructures predicted by MC matches very well with those produced experimentally and the plasmonic properties predicted by these MC simulated structures are also consistent with the features obtained experimentally both qualitative and semi-quantitatively. This study indicates a possible solution to use MC simulation and numerical calculation to guide the design of the plasmonic metasurfaces and metamaterials based on SSL fabrication.