Fabrication and characterization of hybrid Si/ZnO subwavelength structures as efficient antireflection layer.

In this study, we fabricated and characterized three dimensional (3D) silicon (Si)/zinc oxide (ZnO) hybrid subwavelength structures to investigate their antireflective properties. Si nanorods (SiNRs) were fabricated by electrochemical etching, and subsequentially we grew ZnO NRs on SiNR as templates by using hydrothermal synthesis. The morphological and optical properties of hybrid Si/ZnO subwavelength structures were investigated by scanning electron microscopy (SEM) and ultra violet-visible-near infrared (UV-VIS-NIR) spectrophotometer, respectively. The reflectance on SiNRs is greatly reduced comparing with that on the conventional textured Si surface. Moreover, the hybrid SiNR/ZnO NR structures gave the lowest reflectance (< 3%) throughout the broadband spectrum range. We suggest that the combination of SiNRs and ZnO NRs trap light, leading to suppressing light reflection and increasing light scattering to the hybrid structures.