Anisotropic lattice strain relaxation of MgO/SrTiO 3(001) in a textured island growth mode

Abstract

The out-of-plane and in-plane lattice parameters were measured by in-situ reflection high-energy electron diffraction (RHEED) at the initial growth stage of MgO thin films on SrTiO 3(001) substrates in the growth mode of islands. The in-plane lattice was found to relax immediately after initiating the film deposition, and the majority of the in-plane strain was relieved at the film thickness of 2 nm. Beyond the thickness, the in-plane lattice almost was kept unchanged, and the out-of-plane lattice continued to relax gradually. The anisotropic strain can be attributed to the change of strain energy due to film texture during the ripening process. The relationship between strain and texture, grain size was discussed from the viewpoint of energy competition.