Phase and structural characterization of Sr2Nb2O7 and SrNbO3 thin films grown via pulsed laser ablation in O-2 or N-2 atmospheres

摘要

The influence of substrate temperature, process gas, deposition pressure, and substrate type on the phase selection, orientation/epitaxy, and growth morphology of thin films in the SrNbOy (y approximate to 3.0 or 3.5) family was investigated. Pulsed laser deposited films (from a Sr2Nb2O7 target) obtained in both oxygen and nitrogen atmospheres upon various substrates were characterized with X-ray diffraction, energy dispersive spectroscopy, atomic force microscopy, and transmission electron microscopy. In oxygen atmospheres, films adopted the (110)-layered perovskite structure of the target. Higher temperatures, lower pressures of oxygen, and use of (110)-oriented SrTiO3 substrates lead to highly crystalline, epitaxial films of Sr2Nb2O7. The use of nitrogen atmospheres resulted in cubic perovskite SrNbO3 formation: epitaxial, textured, or polycrystalline films were obtained depending on the substrate; no nitrogen incorporation could be observed on the anion sublattice. On SrTiO3, the cubic perovskite films followed a cube-on-cube epitaxy and planar defects were observed to occur on the (110) perovskite planes. (C) 2008 Elsevier Inc. All rights reserved.