Exploring the electronic properties and oxygen vacancy formation in SrTiO under strain

SrTiO (STO) thin films are widely used as substrates in oxide-based devices, and although STO is one of the most studied materials, both experimentally and computationally in its bulk form, the potential for strain engineering of STO thin-films is largely ignored. In this work, we perform Density Functional Theory (DFT) calculations to investigate the tuning of the structural and electronic properties of STO thin films under uni- and biaxial strain. We find that for TiO-terminated STO slab, the band gap changes due to strain are more significant than that of the SrO-terminated surface because the band gap is determined by the TiO layers closer to the surface. Furthermore, we also find that the formation energy of oxygen vacancies depends on the type of strain applied and the position of oxygen vacancies. These findings demonstrate the large and hitherto underexplored perspectives of using strain engineering to modulate the structural and electronic properties of perovskite film materials for a wide variety of energy and electronic applications.