title: Transparent conducting oxides: a δ-doped superlattice approach.
abstract: Metallic states appearing at interfaces between dissimilar insulating oxides exhibit intriguing phenomena such as superconductivity and magnetism. Despite tremendous progress in understanding their origins, very little is known about how to control the conduction pathways and the distribution of charge carriers. Using optical spectroscopic measurements and density-functional theory (DFT) simulations, we examine the effect of SrTiO3 (STO) spacer layer thickness on the optical transparency and carrier distribution in La δ-doped STO superlattices. We experimentally observe that these metallic superlattices remain highly transparent to visible light; a direct consequence of the appropriately large gap between the O 2p and Ti 3d states. In superlattices with relatively thin STO layers, we predict that three-dimensional conduction would occur due to appreciable overlap of quantum mechanical wavefunctions between neighboring δ-doped layers. These results highlight the potential for using oxide heterostructures in optoelectronic devices by providing a unique route for creating novel transparent conducting oxides.
authors.affiliation: Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: Valentino R
authors.initials: VR
authors.lastname: Cooper
authors.affiliation: 1] Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA [2] Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA.
authors.forename: Sung S Ambrose
authors.initials: SS
authors.lastname: Seo
authors.affiliation: 1] Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA [2] Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791, Korea.
authors.forename: Suyoun
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea.
authors.forename: Jun Sung
authors.initials: JS
authors.lastname: Kim
authors.affiliation: 1] Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA [2] Department of Physics, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746, Korea.
authors.forename: Woo Seok
authors.initials: WS
authors.lastname: Choi
authors.affiliation: Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Okamoto
authors.affiliation: Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: Ho Nyung
authors.initials: HN
authors.lastname: Lee
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