title: The Effect of Polar Fluctuation and Lattice Mismatch on Carrier Mobility at Oxide Interfaces.
abstract: Since the discovery of two-dimensional electron gas (2DEG) at the oxide interface of LaAlO3/SrTiO3 (LAO/STO), improving carrier mobility has become an important issue for device applications. In this paper, by using an alternate polar perovskite insulator (La0.3Sr0.7) (Al0.65Ta0.35)O3 (LSAT) for reducing lattice mismatch from 3.0% to 1.0%, the low-temperature carrier mobility has been increased 30 fold to 35,000 cm(2) V(-1) s(-1). Moreover, two critical thicknesses for the LSAT/STO (001) interface are found, one at 5 unit cells for appearance of the 2DEG and the other at 12 unit cells for a peak in the carrier mobility. By contrast, the conducting (110) and (111) LSAT/STO interfaces only show a single critical thickness of 8 unit cells. This can be explained in terms of polar fluctuation arising from LSAT chemical composition. In addition to lattice mismatch and crystal symmetry at the interface, polar fluctuation arising from composition has been identified as an important variable to be tailored at the oxide interfaces to optimize the 2DEG transport.
authors.affiliation: NUSNNI-NanoCore, National University of Singapore , 117411 Singapore.|Department of Physics, National University of Singapore , 117542 Singapore.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Huang
authors.affiliation: NUSNNI-NanoCore, National University of Singapore , 117411 Singapore.|Department of Physics, National University of Singapore , 117542 Singapore.
authors.forename: Kun
authors.initials: K
authors.lastname: Han
authors.affiliation: NUSNNI-NanoCore, National University of Singapore , 117411 Singapore.|Department of Physics, National University of Singapore , 117542 Singapore.
authors.forename: Shengwei
authors.initials: S
authors.lastname: Zeng
authors.affiliation: NUSNNI-NanoCore, National University of Singapore , 117411 Singapore.|Department of Physics, National University of Singapore , 117542 Singapore.
authors.forename: Mallikarjuna
authors.initials: M
authors.lastname: Motapothula
authors.forename: Albina Y
authors.initials: AY
authors.lastname: Borisevich
authors.affiliation: Department of Physics and Astronomy, Vanderbilt University , Nashville, Tennessee 37235, United States.
authors.forename: Saurabh
authors.initials: S
authors.lastname: Ghosh
authors.affiliation: Condensed Matter Science and Technology Institute, School of Science, Harbin Institute of Technology , Harbin 150081, People's Republic of China.
authors.forename: Weiming
authors.initials: W
authors.lastname: Lü
authors.affiliation: NUSNNI-NanoCore, National University of Singapore , 117411 Singapore.
authors.forename: Changjian
authors.initials: C
authors.lastname: Li
authors.affiliation: NUSNNI-NanoCore, National University of Singapore , 117411 Singapore.|Department of Physics, National University of Singapore , 117542 Singapore.
authors.forename: Wenxiong
authors.initials: W
authors.lastname: Zhou
authors.affiliation: Department of Materials Science and Engineering, University of California , Berkeley, California 94720, United States.
authors.forename: Zhiqi
authors.initials: Z
authors.lastname: Liu
authors.affiliation: NUSNNI-NanoCore, National University of Singapore , 117411 Singapore.|School of Physics and CRANN, Trinity College , Dublin 2, Ireland.
authors.forename: Michael
authors.initials: M
authors.lastname: Coey
authors.affiliation: NUSNNI-NanoCore, National University of Singapore , 117411 Singapore.|Department of Physics, National University of Singapore , 117542 Singapore.|Department of Electrical and Computer Engineering, National University of Singapore , 117576 Singapore.|Department of Materials Science and Engineering, National University of Singapore , Singapore 117575, Singapore.|National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS) , 28 Medical Drive, Singapore 117456, Singapore.
authors.forename: T
authors.initials: T
authors.lastname: Venkatesan
authors.affiliation: NUSNNI-NanoCore, National University of Singapore , 117411 Singapore.|Department of Physics, National University of Singapore , 117542 Singapore.|National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS) , 28 Medical Drive, Singapore 117456, Singapore.
authors.lastname: Ariando
keywords: Oxide interface; carrier mobility; lattice mismatch; polar fluctuation; two-dimensional electron gas