Strong second-harmonic response from semiconductor–dielectric interfaces

In this study, an analysis of the second-harmonic generation (SHG) response from surfaces containing dielectric–semiconductor interfaces with sub-wavelength features is presented. The investigated medium is a metamaterial where the SHG response is governed by the symmetry breaking between consecutive layers. The examined material is composed of a periodic structure based on 50 nm silicon nitride and 10 nm indium gallium zinc oxide (IGZO) fabricated on a quartz glass substrate. The elementary cell consists of a pair of materials in an exchangeable order. The preliminary results show a promising application of the amorphous IGZO as a nonlinear optical material, whose optical characteristics can be controlled by the fabrication process itself. Prepared structures give a remarkably high SHG response. For an effective thickness of the structure equal to 240 nm, a more than 250-fold increase in SHG compared to the reference substrate is observed.