Ferroelectric PbTiO3 films grown by pulsed liquid injection metalorganic chemical vapour deposition

Influence of various deposition conditions (deposition temperature, partial oxygen pressure and solution composition) to the growth of ferroelectric PbTiO3 (PTO) films by pulsed liquid injection metalorganic chemical vapour deposition (MOCVD) was examined. Films were grown on LaAlO3 (001), SrTiO3 (001) and sapphire (R-plane) substrates. Pb(thd)(2) and Ti(O'Pr)(2)(thd)(2) (thd = 2,2,6,6-tetramethyl-3,5-heptanedionate) dissolved in toluene were used as precursors. Evolution of film composition, surface morphology and microstructure with deposition conditions were studied. Microstructure of the films was characterized by X-ray diffraction (XRD) in Bragg-Brentano and Schulz geometries and by Raman spectroscopy. Epitaxial films on perovskite substrates consisted of dominant c-axis and minor a-axis textured zones (c-domains and a-domains). The amount of a-domains in films depended mainly on deposition temperature. The twinning in a- and c-domains was observed and twinning (tilt) angles depended on deposition conditions and on substrate. Fully twinned or partially twinned films can be obtained varying deposition conditions. The best quality epitaxial films were obtained on SrTiO3 and LaAlO3 at 650 degrees C. Films on sapphire were mainly polycrystalline.