Oscillation of surface in-plane lattice spacing during epitaxial growth of BaTiO3 and SrTiO3 on SrTiO3(1 0 0)

Abstract In-plane lattice spacing oscillation was observed as functions of surface coverage and growing film thickness by reflection high-energy electron diffraction during the growth of strained BaTiO 3 and unstrained SrTiO 3 epitaxial layers on SrTiO 3 (1 0 0). For BaTiO 3 /SrTiO 3 , the oscillation continued until the critical thickness is reached, whereas for SrTiO 3 /SrTiO 3 , oscillation was observed only at the initial few monolayer growth. The origin of oscillations is discussed in relation to the non-tetragonal elastic distortion occurring at the free edges of 2D single monolayer islands. The amplitude of the oscillation strongly depended on the island size and density.