Hierarchically Ordered Silicon Metastructures from Improved Self-Assembly-Based Nanosphere Lithography.

We develop an improved self-assembly method to obtain a large-area, high-quality templated monolayer mask using the polystyrene spheres. Based on the templated mask, hierarchically ordered Si metastructures with different nanosteps are fabricated using cyclic inductively coupled plasma etching technique. By evaporating a thin gold capping layer on these Si metastructures, their optical properties are comparatively studied using the surface-enhanced Raman scattering spectroscopy. Our proposed technique is highly promising for fabricating a variety of periodic three-dimensional hierarchically ordered metastructures, which could be further utilized for applications in SERS-based biosensors, optical absorbers, metamaterial/metasurface devices, etc.