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

Abstract

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 him 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.