Transparent conducting oxides: A -doped superlattice approach

Journal Article · Wed Jan 01 00:00:00 EST 2014 · Nature Materials

DOI:https://doi.org/10.1038/srep06021· OSTI ID:1149740

Cooper, Valentino R ^[1]; Seo, Sung Seok A. ^[2]; Lee, Suyoun ^[1]; Kim, Jun Sung ^[3]; Choi, Woo Seok ^[1]; Okamoto, Satoshi ^[1]; Lee, Ho Nyung ^[1]

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1. ORNL
2. University of Kentucky, Lexington
3. Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea

Two-dimensional electron gases (2DEGs) at the interface of oxide heterostructures have been the subject of recent experiment and theory, due to the intriguing phenomena that occur in confined electronic states. However, while much has been done to understand the origin of 2DEGs and related phenomena, very little has been explored with regards to the control of conduction pathways and the distribution of charge carriers. Using first principles simulations and experimental thin film synthesis methods, we examine the effect of dimensionality on carrier transport in La delta-doped SrTiO3 (STO) superlattices, as a function of the thickness of the insulating STO spacer. Our computed Fermi surfaces and layer-resolved carrier density proles demonstrate that there is a critical thickness of the STO spacer, below which carrier transport is dominated by three-dimensional conduction of interface charges arising from appreciable overlap of the quantum mechanical wavefunctions between neighboring delta-doped layers. We observe that, experimentally, these superlattices remain highly transparent to visible light. Band structure calculations indicate that this is a result of the appropriately large gap between the O 2p and Ti d states. The tunability of the quantum mechanical wavefunctions and the optical transparency highlight the potential for using oxide heterostructures in novel opto-electronic devices; thus providing a route to the creation of novel transparent conducting oxides.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 1149740
• Journal Information: Nature Materials, Vol. 4
• Country of Publication: United States
• Language: English