Fabrication and Optical Properties of Ferroelectric Photonic Crystals by Electrophoretic Epitaxial

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This research concerns the fabrication and optical properties of ferroelectric photonic crystals by a sol-gel method combined with electron-beam lithography used for preparation of resist molds. Specifically, an investigation on a set of the following experiments has been made and the main results obtained are described below.1. Fabrication of two-dimensional (Pb, La)(Zr, Ti)O_3 [PLZT] photonic crystals using a sol-gel method and their optical properties :2D-photonic crystals consisting of PLZT ceramic pillars arrayed in a hexagonal lattice have been successfully fabricated on Nb-doped SrTiO_3 [Nb-STO] single crystal substrates, which are conductive and act as electrode, by casting a commercially obtained PLZT precursor solution into resist molds formed on the Nb-STO substrates using electron beam (EB) lithography, followed by firing at 725℃ in air. The obtained 2D-PLZT photonic crystals were confirmed to exhibit characteristic optical reflection spectra attributable to photonic band g … More aps (PBGs) formed in the photonic crystals. And moreover, the individual PLZT pillars have been revealed to be ferroelectric, confirmed by measurements of piezoelectric response characteristics using scanning probe microscopy (SPM).2. Fabrication of BaTiO_3 [BTO] photonic crystals by electrophoretic deposition (EPD) of BTO nanocrystals:2D-photonic crystals consisting of BTO ceramic pillars arrayed in a hexagonal lattice have been successfully fabricated on Pt/SiO_2/Si substrates, on which resist molds were formed by EB-lithography, by an EPD method using suspension of 10-15 nm BTO nanocrystals synthesized by high concentration alkoxides sol-gel method. Nanocrystalline BTO pillars were heat-treated at 600-700℃ in air to sinter them. The obtained individual BTO pillars exhibited definite ferroelectricity, confirmed by measurements of piezoelectric response characteristics by SPM.3. Observation of epitaxial assembly of BTO nanocrystals into aggregates with crystallographic single crystal nature :Fabrication of BTO micropatterns with crystallographic single crystal nature by nanocrystals EPD is the main objective of this research. To make it possible the establishment of a technique that can realize formation of nanoparticles aggregation self-assembled to have the same crystallographic coordinates is a must. We succeeded for the first time in finding definite evidence for epitaxial assembly of BTO nanocrystals in aggregates produced under hydrothermal conditions, confirmed by analyses of their dark-field and high resolution transmission electron microscopy (TEM) images and electron diffraction images. Less