title: Creating Two-Dimensional Electron Gas in Polar/Polar Perovskite Oxide Heterostructures: First-Principles Characterization of LaAlO3/A(+)B(5+)O3.
abstract: By using first-principles electronic structure calculations, we explored the possibility of producing two-dimensional electron gas (2DEG) at the polar/polar (LaO)(+)/(BO2)(+) interface in the LaAlO3/A(+)B(5+)O3 (A = Na and K, B = Nb and Ta) heterostructures (HS). Unlike the prototype polar/nonpolar LaAlO3/SrTiO3 HS system where there exists a least film thickness of four LaAlO3 unit cells to have an insulator-to-metal transition, we found that the polar/polar LaAlO3/A(+)B(5+)O3 HS systems are intrinsically conducting at their interfaces without an insulator-to-metal transition. The interfacial charge carrier densities of these polar/polar HS systems are on the order of 10(14) cm(-2), much larger than that of the LaAlO3/SrTiO3 system. This is mainly attributed to two donor layers, i.e., (LaO)(+) and (BO2)(+) (B = Nb and Ta), in the polar/polar LaAlO3/A(+)B(5+)O3 systems, while only one (LaO)(+) donor layer in the polar/nonpolar LaAlO3/SrTiO3 system. In addition, it is expected that, due to less localized Nb 4d and Ta 5d orbitals with respect to Ti 3d orbitals, these LaAlO3/A(+)B(5+)O3 HS systems can exhibit potentially higher electron mobility because of their smaller electron effective mass than that in the LaAlO3/SrTiO3 system. Our results demonstrate that the electronic reconstruction at the polar/polar interface could be an alternative way to produce superior 2DEG in the perovskite-oxide-based HS systems.
authors.affiliation: State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China , Chengdu, Sichuan 610054, P. R. China.|Department of NanoEngineering, University of California, San Diego , 9500 Gilman Drive, Mail Code 0448, La Jolla, California 92093-0448, United States.
authors.forename: Yaqin
authors.initials: Y
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China , Chengdu, Sichuan 610054, P. R. China.
authors.forename: Wu
authors.initials: W
authors.lastname: Tang
authors.affiliation: Department of NanoEngineering, University of California, San Diego , 9500 Gilman Drive, Mail Code 0448, La Jolla, California 92093-0448, United States.
authors.forename: Jianli
authors.initials: J
authors.lastname: Cheng
authors.affiliation: Department of NanoEngineering, University of California, San Diego , 9500 Gilman Drive, Mail Code 0448, La Jolla, California 92093-0448, United States.
authors.forename: Maziar
authors.initials: M
authors.lastname: Behtash
authors.affiliation: Department of NanoEngineering, University of California, San Diego , 9500 Gilman Drive, Mail Code 0448, La Jolla, California 92093-0448, United States.
authors.forename: Kesong
authors.initials: K
authors.lastname: Yang
keywords: KTaO3; first-principles; oxide heterostructures; perovskite; polar/polar; two-dimensional electron gas