Atomic control of homoepitaxial SrTiO3 films using laser molecular beam epitaxy

Atomically flat SrTiO3 (STO) substrates can be prepared by oxygen-annealing, however, step structures are known to be difficult to control. Various step structures of original substrates could be modified by growth of homoepitaxial films using laser molecular beam epitaxy (MBE). On substrates with a mixture of 1 and 2 unit cell (uc) steps, two kinds of films were grown: their growths were interrupted at either a top or a bottom of reflection high-energy electron diffraction (RHEED) intensity oscillations. The step structure of the top-interrupted film was similar to that of the substrate. However, in the bottom-interrupted film, bunched steps could be removed after deposition of only 2.5 monolayers (ML) and 1 uc steps could be generated. The recovery of the RHEED intensities reflecting the step height modification was found out to have a strong azimuthal dependence of incident electron-beam (e-beam) direction with respect to the step direction. (C) 1999 Published by Elsevier Science B.V. All rights reserved.