Biomimetic Antireflective Si Nanopillar Arrays

Biomimetic Silicon (Si) nanopillar arrays with antireflection behavior were created based on the combination of self-assembly of polymer spheres into two-dimensional (2D) arrays and reaction-ion etching (RIE). The results indicate that for the Si nanopillars created with 460 nm sphere masks, the aspect ratios of the 3 nanopillar arrays range from 0.79 to 0.9,w here the highest one is created by 290s etching. The Fresnel reflection can be reduced by inserting a layer with an intermediate index between two media. The Si nanopillar arrays have flat tops and grooves and that the residual reflection of 8% is induced by the index changing abruptly at the air/top and groove/air interfaces. The reflectivity is reduced by optimization of the etching conditions and choosing proper spheres to obtain the perfect tapered shapes.