Structural and luminescent properties of terbium doped strontium titanate xerogel
We report on synthesis and photoluminescence of sol-gel derived terbium doped strontium titanate on monocrystalline silicon and in the porous anodic alumina matrix. The microstructure and morphology of the samples are analyzed by X-ray diffraction and scanning electron microscope analyses. The thickness of the spin-on films deposited on silicon is about 115 and 170 nm due to the annealing temperature 750 and 1000 °C respectively. The samples reveal terbium luminescence in the visible range.
CHARACTERIZATION OF POLYCRYSTALS OF STO DOPED WITH EUROPIUM: Sr1 − XEuxTiO3
ABSTRACT The crystalline structure, microstructure, luminescence and dielectric properties of SrTiO3 polycrystals doped with Eu3 + at different compositional ratios were studied by XRD, XPS and SEM analyses. Rietveld refinement of the XRD data shows a slight decrease of the cell volume indicating the incorporation of Eu3 + in the crystalline structure. The structure remains cubic (Pm3m) at room temperature in the analyzed range of Eu doping. XPS studies revealed the characteristic signal of the Eu3 + ion in the solid solution. From the dielectric behavior it was possible to identify that Eu doping produces changes with respect to pure STO. Photoluminescence spectra taken at room temperature showed that Eu3 + doping of SrTiO3 causes emission peaks at 590 and 616 nm.
In situ study of interface reactions of ion beam sputter deposited (Ba0.5Sr0.5)TiO3 films on Si, SiO2, and Ir
(Ba0.5,Sr0.5)TiO3 (BST) thin films were deposited on MgO, Si, SiO2 and Ir surfaces by ion beam sputter deposition in oxygen at 700 °C. In situ spectroscopic ellipsometry (SE) has been used to investigate the evolution of the BST films on different surfaces during both deposition and postannealing processes. First, the optical constants of the BST films in the photon energy range of 1.5–4.5 eV were determined by SE analysis on crystallized BST films deposited on MgO single crystal substrates. The interfaces in BST/Si and BST/SiO2/Si structure were examined by SE and Auger electron spectroscopy depth profiles. Subcutaneous oxidation in the BST/Ir structure was observed by in situ SE during both ion beam sputter deposition and postdeposition annealing in oxygen at 700 °C. A study of the thermal stability of the Ir/TiN/SiO2/Si structure in oxygen at 700 °C was carried out using in situ SE. The oxidation of Ir was confirmed by x-ray diffraction. The surface composition and morphology evolution after oxidation ...