Atomic control of substrate termination and heteroepitaxial growth of SrTiO₃/LaAlO₃ films

The roles of substrate termination in the growth behaviors of SrTiO₃ (STO) films were investigated. With heat treatment and an atomic layer deposition technique, LaAlO₃ (LAO) substrates with two kinds of terminations, i.e., LaO-and AlO₂-terminated ones, could be prepared. On top of them, STO films were grown by using laser molecular beam epitaxy. In the case of the STO/LaO-LAO film, a transition from layer-by-layer growth to island growth was observed after growth of about 10 monolayers (ML). On the other hand, the STO/AlO₂-LAO film could be grown in a layer-by-layer mode with a flat surface up to 40 ML. We suggest that defects induced by charge compensatoin influence the strain states and the physical properties of oxide heterostructures significantly.