In Situ Planarization of Huygens Metasurfaces by Nanoscale Local Oxidation of Silicon

Metasurfaces are becoming a flourishing field of research, with diverse applications, such as planar optical components and structural colors. While metallic metasurfaces are typically few tens of nanometers in their thickness, their dielectric counterparts typically span few hundreds of nanometers in thickness variations. This makes the stacking of multilayers a bit challenging. To mitigate this challenge, we have developed a new approach for the realization of dielectric metasurfaces. Our approach is based on the nanoscale local oxidation of silicon (LOCOS), allowing to achieve planar metasurface structures. We have utilized this approach for the design, fabrication and characterization of amorphous silicon based all-dielectric Huygens metasurfaces. These metasurfaces show clear electric and magnetic resonances, which can be structurally tuned. The obtained results are in good agreement with numerical simulations taking into account the unique shape of the nanoantennas. Relying on a robust approach for their realization, and combined with the important feature of in situ planarization, we believe that such planarized metasurfaces will become a viable technology for future applications.