Structural Behavior of Thin BaTiO3Film Grown at Different Conditions by Pulsed Laser Deposition

Thin epitaxial BaTiO3(BTO) films having a high crystallinity and uniformity of grains were deposited on the SrTiO3(STO) substrates. When the oxygen pressure is from 0.04 to 70 Pa the lattice constant decreases from 4.1100 to 3.9972 Å and the orientation normal to the substrate changes from (001) to (100). The surface topography changes from flat to hilly with a surface roughness (rms) changing between 1.2 nm at 0.7 Pa, 3.4 nm at 7 Pa and 6.4 nm at 70 Pa. At the substrate temperature of 550, 750 and 850°C the surface topography of the films varies from corrugated structure to rectangular grain and the surface roughness increases from 1.2, 3.4 to 3.4 nm. The epitaxial BTO films were also deposited on the YBCO/LaAlO3(YBCO/LAO) substrates at 750°C and 7 Pa. The films have a rough surface (rms=29.1 nm), but a good uniformity of grains. The c-axis oriented BTO films with a poor crystallinity were deposited on the MgO substrates at 750°C and 7 Pa. The films have a smooth surface (rms=1.0 nm), but a poor uniformity of grains. The interfaces between the BTO films and the substrates were determined by transmission electron microscopy (TEM).