Influence of deposition time on the morphology and optical properties of SiO2-ZnO composite photonic crystals

SiO₂ photonic crystal were successfully prepared by vertical deposition and then used as a template to fabricate SiO₂-ZnO composite photonic crystals on ITO substrates by electrodeposition and subsequent calcination. A number of different deposition times were used. The morphologies of the silica opals and SiO₂-ZnO composite photonic crystals were investigated by scanning electron microscopy. It was found that ZnO particles grew randomly on the surfaces of the silica spheres when the deposition time was short. As the deposition time was increased, the ZnO particles grew evenly on the surfaces of the silica spheres so that the interstitial space of the silica template was filled with ZnO particles. Reflectance spectra of the SiO₂-ZnO composite crystals revealed that all of the fabricated photonic crystals exhibit a photonic band gap in the normal direction.