Structural behavior of thin BaTiO3 film 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 70Pa the lattice constant decreases from 4.1100 to 3.9972 Angstrom and the orientation normal to the substrate changes from (001) to (100). The surface topography changes from Bat 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 degrees 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 degrees 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 degrees 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).