Fabrication and characterization of three-dimensional core–shell structure ZnO photonic crystals by magnetron sputtering based on opal template

Using polystyrene (PS) opal templates and RF magnetron sputtering, three-dimensional (3D) zinc oxide (ZnO) photonic crystals (PCs) of core–shell structures are prepared. Scanning electron microscopic (SEM) spectra show that there are up to five layers in the samples while X-ray diffraction (XRD) spectra indicate that they are of hexagonal wurtzite structures, preferentially (0 0 2) oriented. Ultraviolet–visible (UV–vis) spectra confirm the existence of photonic band gaps (PBG) in the samples.