ORIENTATION AND CRYSTAL-STRUCTURE OF SRTIO3 THIN-FILMS PREPARED BY PULSED-LASER DEPOSITION

SrTiO3 thin films are grown on MgO(001) substrates at growth temperatures between 600-800 degrees C and at oxygen pressures between 10(-1)-10(-6) Torr. The initial stage of growth is controlled by graphoepitaxy with a cube-on-cube orientation. In the growth temperature range from 600 degrees C to 740 degrees C, graphoepitaxy occurs only at 10(-6) Torr or 740 degrees C. At 10(-6) Torr the internal and kinetic energies of the evaporated particles contribute to the surface mobility necessary for graphoepitaxy, while at 740 degrees C heat energy assures surface migration. However, at 800 degrees C, the orientation changes to (111) with increasing thickness. This is because the dominant factor of film growth changes to the formation of a close-packed surface as the growth front gets farther from the substrate surface.