First-principles studies of perovskite thin films and heterostructures

The growth of oxides on semiconductors is of great interest for electronics applications; however, the effects of film growth, atomic adsorption, and strain can have fundamental effects on the properties of the oxides in question. In this dissertation, we use density functional theory to calculate the properties of SrTiO₃ and BaTiO₃, and discover the effects of the environment on the electronic and atomic properties of these systems. We examine the effects of H adsorption on the SrTiO₃ and BaTiO₃(001) surfaces, and discover the coverage-dependent onset and retreat of metallic surface states. We calculate the effect of Pt film growth on BaTiO₃, and study the effects on the polarization of BaTiO₃ for different Pt/BaTiO₃ interfaces. We study how strain and interfacial chemistry affect the ferroelectricity of BaTiO₃/Ge and BaTiO₃/SrTiO₃/Ge heterostructures. We also discuss the development of two-dimensional conducting states created in BaTiO₃/SrTiO₃ heterostructures.