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

Abstract

SiO 2 photonic crystal were successfully prepared by vertical deposition and then used as a template to fabricate SiO 2 -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 SiO 2 -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 SiO 2 -ZnO composite crystals revealed that all of the fabricated photonic crystals exhibit a photonic band gap in the normal direction. [7]. However, the fabrication of 3-D opal photonic crystals is still a technical challenge, because many kinds of intrinsic defects such as plane defects, line defects, and dot defects appear during self-assembly. During self-assembly, surface charge *Corresponding author (email: fengbx@lzu.edu.cn) on colloidal spheres is a key element in successfully producing high quality colloidal crystals. Some scientists had fabricated SiO 2 photonic crystals with high quality by enhancing surface charge on SiO 2 spheres via modification with succinic acid [8]. In this work, vertical deposition was chosen as the self-assembly method to fabricate SiO 2 photonic crystal templates as it provides a relatively simple approach to obtaining high quality opal films.Silica or polymer opals do not have a full band gap because of their low refractive index (1.47 for silica). However, these opals are calculated to have a photonic band gap in the (111) direction, so opal-based materials, such as composite photonic crystals with different fillings and inverted opals [9][10][11], are of interest. ZnO is an important semiconductor material with a wide electronic band gap, which has a higher refractive index (2.1) than other materials. As a result, an increasing number of SiO 2 -ZnO composite photonic crystals have been fabricated by a range of methods [12,13].In this work, SiO 2 -ZnO composite photonic crystals were fabricated by electrodeposition followed by calcination at

Stress Development in Hard Particle Coatings in the Absence of Lateral Drying

“…Coatings made from hard particles are used in many industrial applications including battery electrodes, nanoparticle inks, photonic crystals, and antireflective coatings . Often, particle‐based coatings are prepared by depositing a colloidal suspension onto a substrate and drying.…”

Fabrication and Characterization of Tin Oxide Inverse Opal by Template Method

“…Figure 2 shows that the 270nm PS colloidal crystal has good lattice structure. The photonic band gap position is in 620 nm that is corresponding to Bragg's law [10] : A S-4800ⅡFESEM was used for direct characterization of the inverse opal of SnO 2 . Figure 3 (a) shows that the hundreds of square millimeters of SnO 2 inverse opal could be achieved, but some defects can be checked from this picture, some of the defects were the photocopy of the PS spheres opal defects, some of the defects such as over-layer formation was in the process of excessive infiltration of SnO 2 precursor solution.…”