Specific cation stoichiometry control of SrMnO3-δ thin films via RHEED oscillations

Cubic heteroepitaxial (001) SrMnO3-δ (SMO) films were grown on SrTiO3 substrates by atomic alternating layer molecular beam epitaxy. Precise control of cation stoichiometry was achieved by in situ reflection high-energy electron diffraction (RHEED) oscillation. During SMO film growth, a correlation between RHEED oscillation features and the cation stoichiometry/monolayer dose was established. In non-stoichiometric films, there were out-of-plane lattice expansions due to off-stoichiometry-dependent defects, including Ruddlesden–Popper SrO planar faults in Sr-rich films and Sr vacancy defect clusters in Mn-rich films.