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° 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° C to 740° C, graphoepitaxy occurs only at 10-6 Torr or 740° 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° C heat energy assures surface migration. However, at 800° 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.