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 st ep structures of original substrates could be modified by growth of homoepi taxial 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: th eir growths were interrupted at either a top or a bottom of reflection high -energy electron diffraction (RHEED) intensity oscillations. The step struc ture of the top-interrupted film was similar to that of the substrate. Howe ver, in the bottom-interrupted film, bunched steps could be removed after d eposition of only 2.5 monolayers (ML) and 1 uc steps could be generated. Th e recovery of the RHEED intensities reflecting the step height modification was found out to have a strong azimuthal dependence of incident electron-b eam (e-beam) direction with respect to the step direction. (C) 1999 Publish ed by Elsevier Science B.V. All rights reserved.