Fabrication of Si-based dielectric resonators: Combining etaloning with Mie resonances

We use low-resolution optical lithography and plasma etching joined with solid state dewetting of crystalline, ultra-thin silicon on insulator (c-UT-SOI) to form monocrystalline, atomically-smooth, silicon-based Mie resonators in well controlled large periodic arrays.

The dewetted islands have a typical size in the 100 nm range, about one order of magnitude smaller than the etching resolution. Exploiting a 2μm thick SiO2 layer separating the islands and the underlying bulk, silicon wafer, we combine the resonant modes of the antennas with the etalon effect. This approach sets the resonance spectral position, improves the structural colorization and the contrast between scattering maxima and minima of individual resonant antennas.

Our results demonstrate that templated dewetting enables to form defect-free, faceted islands that are much smaller than the nominal etching resolution and that an appropriate engineering of the substrate improves their scattering properties. These results are relevant to applications in spectral filtering, structural color and beam steering with all-dielectric photonic devices.