Artificial Charge Modulations in La-Doped SrTiO3 Superlattices

A major obstacle to achieving high free-carrier densities in semiconductors is that electrically active dopants are, by definition, standard. The Coulomb repulsion between the charged impurities keeps these atoms widely spaced, preventing the formation of a good conductor [1]. In contrast, by choosing a material with a higher dielectric constant, and a lower dopant diffusivity, these problems can be overcome, and a wider range of physical (especially extremely non-linear) properties can be obtained within a common materials system. We have explored perovskites based on SrTiOsub3 as building blocks for atomic-scale superlattices.