ASYMMETRIC ROCKING CURVE STUDY OF THE CRYSTAL-STRUCTURE ORIENTATIONS FOR BATIO3 THIN-FILMS GROWN BY PULSED-LASER DEPOSITION

We have investigated systematically the oxygen pressure dependences of the crystalline phases and the crystallographic orientations of BaTiO 3 thin films by means of asymmetric rocking curves. Epitaxial BaTiO3 t hin films were grown on SrTiO3 (001) substrates by pulsed laser deposi tion (PLD) under different oxygen pressures. The X-ray diffraction the ta/2 theta scans showed no diffraction peaks from impurity phases or r andomly oriented grains, indicating that the thin films were single ph ase BaTiO3. The XRD omega rocking curves indicated that the BaTiO3 thi n films had a very high degree of crystallinity. The XRD phi scans sho wed that no in-plane misorientation existed in the BaTiO3 thin films. The results of asymmetric rocking curves showed that the BaTiO3 thin f ilms grown under higher oxygen pressures(> 12 Pa) were tetragonal with a-axis orientation, those grown under lower oxygen pressures (<7 Pa) were tetragonal with c-axis orientation, and those grown under interme diate oxygen pressures (similar to 7-12 Pa) were cubic. (C) 1998 Elsev ier Science B.V. All rights reserved.